This study deals with the preparation of polymer nanocomposites. The first aim of this work was the preparation of modified fillers from two types of natural clays. The first was sodium type of montmorillonite (MMT), and the second was bentonite, which contains more constituents than MMT (for example quartz, calcite, illite and others). Further, two methods of intercalations were studied. Ion-dipole method using the intercalation agent hexadexylamine (HDA), and ion-exchange method utilizing the modifying agent cetyltrimethylammonium bromide (CTAB). For the ion-dipole method various concentrations of clay/HDA were tested, while different additives, time of reaction and concentrations of CTAB were variables for the ion-exchange method. Consequently, prepared samples were characterized by X-ray diffraction and FTIR spectroscopy. Moreover, the commercially modified nanofiller, Cloisite® 25A, and the natural clays were tested as well to compare final properties with other modified nanofillers. Then, four intercalated samples with the highest d-spacing were selected for the following research. In the second part of this study chosen modified nanofillers, as well as Cloisite® 25A and natural fillers, were compounded with a polymer matrix, called Surlyn® 9721. It is a copolymer of polyethylene and methacrylic acid. Consequently, following properties was measured: permeability for nitrogen and water vapour, stress-strain properties and thermal properties.

PC73

Polypropylene/Boehmite composite fibres, Spinning and mechanical properties

M. Hricová, A. Marcinčin, J. Legéň

Department of Fibres and Textile Chemistry, Institute of Polymer Materials, FCHPT, STU in Bratislava, Radlinského 9, SK-812 37 Bratislava, Slovak Republic (marcela.hricova / stuba.sk)

Development of the polypropylene (PP) based composites, containing inorganic nanofillers is focused mainly on improvement of the mechanical properties, UV barrier properties and lowering of combustibility of polymers. In this paper, the effects of rheological properties of PP/boehmite composites, selected compatibilisers and spinning conditions on selected mechanical properties of PP composite fibres are presented.

The PP Moplen 500R (PP500R) and PP Moplen 561N (PP561N), commercial boehmite Disperal 40 (D40) as well as two types of compatibilisers: TEG (alkyl-polysiloxane) and S44P (ester of stearic acid and polypropylene glycol) were used in experimental work. The model PP/D40 composite fibres were prepared using two-step process: preparation of PP500R/D40 (5.0 wt%) concentrate dispersions and spinning of mixture of the PP561N and PP500R/D40 concentrate dispersions to obtain the final concentration of boehmite (0.5; 1.0 and 3.0 wt%) in the fibres.

The rheological measurements have confirmed any negative effect of solid particles of boehmite on flow properties of PP500R/D40 composites. Boehmite (5.0 wt%) increased the melt viscosity of PP about 15-30% but practically did not change its non-Newtonian behaviour. Both compatibilisers decreased composite melt viscosity approximately on the level of PP 500R one. The tenacity and Young's modulus of PP composite fibres containing up to 1.0 wt% of D40 were significantly increased in comparison with unmodified PP fibres. Concentrations of Disperal 40 in PP above 1.0 wt% gradually decrease basic mechanical properties of PP composite fibres.

PC74

A macro azo initiator intercalated in SODIUM MONTMORILLONITE: Shape memory and physical properties of poly(ethyl methacrylate)

M.S. Kim, J.H. Kim, Y.R. Lee, J.Y. Jang, H.M. Jeong

Department of Chemistry, University of Ulsan,Ulsan 680-749, Korea

(hmjeong / mail.ulsan.ac.kr)

In this study, we intercalated macroazoinitiator (MAI) into the gallery of sodium montmorillonite (Na-MMT), and the Na-MMT intercalated with MAI was used in the polymerization of ethyl methacrylate to obtain nanocomposites. We examined the shape memory effect of the nanocomposites along with their mechanical and rheological properties because we anticipated that the Na-MMT intercalated with PEG building block linked to poly(ethyl methacrylate) can perform its role as a fixed phase in shape memory behavior as well as a moiety to enhance mechanical properties.

In the nanocomposites prepared by in situ polymerization of ethyl methacrylate with macroazoinitiator intercalated at the gallery of Na-MMT, we observed that the PEG segment originating from macroazoinitiator was intercalated at the gallery of Na-MMT because of the affirmative interaction between Na-MMT and the PEG segment. The mechanical and rheological properties showed that the heterogeneously dispersed Na-MMT, which is intercalated with a PEG segment, effectively acts as filler and physical crosslinker. The shape memory behavior showed that only 1.2 wt% of Na-MMT can perform efficiently as a fixed phase to inhibit the slippage of matrix molecules and excess amounts of fixed phase, more than 7 wt% of Na-MMT, were not conducive for shape recovery.

PC75

THERMAL DEGRADATION BEHAVIOUR OF POLY(3-HYDROXYBUTYRATE)/CLOISITE 30B NANOCOMPOSITES

M. Erceg, T. Kovačić, I. Klarić

Department of Organic Technology, Faculty of Chemistry and Technology, Teslina 10/V, 21 000 Split, Croatia (merceg / ktf-split.hr)

Poly(3-hydroxybutyrate) (PHB) is a fully biodegradable thermoplastic which has recently drawn much attention as an environmentally harmless alternative to petrochemical derived plastics. However, there is no large commercial production of PHB products because of its very low thermal stability at processing temperatures, pronounced brittleness and high cost. Recently developed nanocomposites consisting of a polymer and only a few percent of layered silicates as environmentally friendly nanofillers, often exhibit improved thermal, mechanical and other properties when compared to pure polymers and conventional composites.

This investigation is focused on the preparation of polymer nanocomposites of PHB with organically modified montmorillonite Cloisite 30B (30B), the effects of Cloisite 30B loading on the thermal stability of PHB and the determination of kinetic parameters and mechanism of their non-isothermal degradation.

PHB/30B nanocomposites with compositions 100/0, 100/1, 100/3, 100/5, 100/7 and 100/10 by weight were prepared by solution intercalation method.

The non-isothermal thermogravimetric analysis of PHB/30B nanocomposites was carried out over the temperature range 50-500°C at four heating rates (2,5; 5; 10 and 20°Cmin-1) in the nitrogen atmosphere.

The onset decomposition temperatures (T°) and the temperatures at the maximal degradation rate (Tmax) of PHB/30B 100/1, 100/3 and 100/5 are higher compared to pure PHB and therefore their thermal stability is improved. Sample PHB/30B 100/7 shows similar and sample PHB/30B 100/10 lower values of T° and Tmax compared to pure PHB.

The invariant kinetic parameters method1 (IKP) was used in combination with isoconversional methods (Flynn-Wall-Ozawa2 and Kissinger-Akahira-Sunose3) to determine the kinetic triplet for the PHB/30B non-isothermal degradation, i.e. the activation energy (E), the pre-exponential factor (A) and the conversion function f(a). By means of isoconversional methods, E and its dependence on conversion (a) are obtained. The values of Einv and Ainv obtained by IKP method were used for numeric evaluation of f(a). The dependence of f(a) vs. a can not be fitted precisely by any ideal kinetic model but its shape suggests the true f(a) characteristic. Finally, the true kinetic triplets for the non-isothermal degradation of each PHB/30B nanocomposite were obtained.

References

1) A.I. Lesnikovich, S.V. Levchik J Therm Anal, 1983, 27, 89.

2) T. Ozawa, Thermochim. Acta, 1992, 203, 159.

3) T. Akahira, T. Sunose Res Report Chiba Inst Technol., 1971, 16, 22.

PC76

MOLECULAR MOBILITY AND GLASS TRANSITION DYNAMICS OF POLYCYANURATE/ORGANOCLAY NANOCOMPOSITES

P. Maroulas^a, S. Kripotou^a, P. Pissis^a, G. Anthoulis^a, E. Kontou^a, A. Fainleib^b, I. Bei^b

^aDepartment of Physics, National Technical University, Zografou Campus, 157 80 Athens, Greece, e-mail : pmaroul / mail.ntua.gr

^bInstitute of Macromolecular Chemistry of National Academy of Sciences, 48, Kharkivs'ke shose, 02160 Kyiv, Ukraine

Polycyanurate networks (PCNs) based on bisphenol A cyanate ester (BADCy) were synthesized under presence of organically modified montmorillonite (MMT), hopefully improving mechanical properties of PCN. The resulting nanocomposites differ in MMT content used, mixing conditions and the type of MMT modifier. Organically modified MMT used is commercially found with product names Cloisite 30B and Cloisite 15A. Mixing of the prepolymers with MMT was either mechanical or using ultrasound.

Dielectric techniques, including broadband dielectric relaxation spectroscopy (DRS) and thermally stimulated depolarization currents (TSDC) along with dynamic mechanical analysis (DMA), and to a lesser extent differential scanning calorimetry (DSC), were employed to investigate molecular mobility and glass transition dynamics in relation to morphology in polycyanurate/Cloisite nanocomposites. The local, secondary γ and β relaxations of PCN, the primary α relaxation, associated to the glass transition of the nanocomposite, and the Maxwell-Wagner-Sillars relaxation, related to microphase-separated morphology, were studied in detail. While the relaxations' position intensity and shape seems almost unaffected by the presence of MMT, dynamic glass transition temperature was found to decrease with the increase of MMT content along with an increase of conductivity. Further heating of specimens has a post curing effect accompanied with a shift of β relaxation to higher frequencies. Future in-situ dielectric measurements will hopefully provide significant information of the polycyclotrimerization of BADCy in presence of MMT.

PC77

INFLUENCE OF THE NANOMETER-SCALE STRUCTURE OF AN ISOCYANATE OLIGOMERIC CHAIN EXTENDER IN DETERMINING NOVEL POLYURETHANE BLENDS WITH HARD SEGMENTS OF CONFORMATIONAL MOBILITY

C. Prisacariu

Institute of Macromolecular Chemistry "Petru Poni", Aleea Grigore Ghica Voda, nr. 41 A, 700487, Iasi, Romania ( crispris / icmpp.ro)

The present paper is part of a wider study on a series of systems of polyurethanes (PUs) where a novel diisocyanate (DI) of conformational mobility, 4,4'-dibenzyl diiscyanate (DBDI) was included in the hard block chemical structure. The aim was to improve understanding of the influence of the DI - chain extender (CE) couple on the molecular/supramolecular structure at the nm-scale in PU systems. Novel PU systems were achieved by approaching the 'one shot' synthesis route either in solution or in melt, in two distinct cases: when using 4,4'-diphenyl methane diisocyanate (MDI) as a conventional DI with a rigid geometry, and when using DBDI which displays a variable geometry due to the presence of a rotation axis -CH₂-CH₂ between the two aromatic rings bearing the two NCO groups. In both cases the DI was employed with CE ethylene glycol (EG), and with the macrodiol poly(ethylene) adipate (PEA). DBDI displays the same reactivity as MDI against n - butanol. On employing the one shot synthesis route, when using either MDI or DBDI, in the first stage there appear oligomers with preponderant -[DI-EG]_n- structures. The oligomers corresponding to the -[MDI-EG]- type remain in solution of DMF due to the high interaction between oligomer - DMF. The situation changes dramatically when using DBDI in the PU synthesis: due to the intramolecular rotation of the DBDI scheleton, the incipient growing oligomer -[DBDI - EG]- adopts a plan parallel structure which allows a more compact intermolecular packing of the growing oligomers leading to phase separation, with a characteristic length of ca 20nm and to hard phase crystallization. Thus, the interaction between oligomer-oligomer becomes preponderant towards the interaction between oligomer - DMF and in solution there appear life species in suspension which continue to grow by interphasic reactions. As a result of the PU polyaddition with DBDI by the 'one shot 'synthesis route either in melt or in solution, it obtained opaque PU blends of two copolymers, one of which is soluble in DMF, the other is insoluble in DMF. In contrast, when using the conventional MDI, by selective dissolution in DMF, it obtained homogeneous soluble polymers inseparable in fractions. The materials were characterized by means of X-ray measurements (WAXS), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). These results provide new insight into the role played by nm-scale DI-CE oligomer structures in determining new PU blends of a bicomponent macromolecular structure.

PC78

CAN NANOCOMPOSITES OF PALYGORSKITE WITH COMPLEXING SILANES BE USED AS TOXIC CATION ADSORBENT? INSIGHT INTO ADSORPTION PROPERTIES PLUS HYDROLYTIC STABILITY

T. Kovalchuk*^a, M. Kusminska^a, A. Koriakin^a, I.Zarov^a, V. Zaitsev^a, J-B d'Espinose^b

^aNational T.Shevchenko University, Vladimirskaya 64, Kiev Ukraine ^bEcole Supérieure de Physique et de Chimie Industrielles, 10 Rue Vauqelin Paris, France kovalchu / yahoo.com

Natural clays are excellent and cheap adsorbents, which can be tailored to a particular application by acid and thermal treatment, and functionalisation with silanes. By using composites of palygorskite (Pal) and complexing silanes, hybrid organominerals with improved adsorptive properties toward toxic cations are obtained. Such materials are considered to be a promising alternative to synthetic ion-exchangers. Functionalisation of Ukrainian Pal (S=146 m²∙g^-1) is achieved via grafting with toluene solution of silanes (OMe)₃SiPrNH₂ [Am], (OEt)₃SiPrNHC₂H₄NH₂ [En], (OEt)₃SiPr-SH [SH], and Et₃N catalyst, followed with the thermal treatment to afford polycondensation. Amount of the functional groups, according to pH-titration, is as follows:

According to DRIFT, TG-MS and ²⁹Si MAS NMR study, the silane layer in the composites is polymerised (observed as T₃-species) and grafted to the surface via covalent bonding ≡Si-O-Si to edge silanol groups (Q₂-species, consumed). While the starting Pal can be used for removal of Cu²⁺ from aqueous solutions with 0.1-0.2 mmol∙g^-1 capacity, the hybrid materials are much more efficient. They offer increased affinity, already at low pH, and capacity (i.e. 0.4-0.7 mmol∙g^-1 at pH 5.5). The strong improvement of sorption affinity and capacity is correlated to and is due to the coordination with the organic functions. Hydrolytic stability of these materials in aqueous solutions is a key-issue for their practical application. A thourough study, {involving repeated treatments of the composites with aqueous solutions of high m (0.1N KCl), extreme pH (3-9) and T°C}, show that a portion of the polysiloxane is removed from the composite. Only a part of groups, 0.15-0.25 mmol∙g^-1, presumably those, covalently attached to the surface hydroxyls, can be retained during prolonged use and, therefore, are useful in adsorbent preparation. Moreover, this amount can be increased if additional Si-OH groups are generated in a starting palygorskite via activation treatment before preparation of organominerals.

PC79

THE PREPARATION OF MIXTURES BASED ON LAYERED SILICATES

V. Rabová^a, P. Hron^b

^aDepartment of Polymers, The Institute of Chemical Technology, Technická 5, CZ-166 28 Praha 6, Czech Republic (rabovav / vscht.cz )

^bDepartment of Polymers, The Institute of Chemical Technology, Technická 5, CZ-166 28 Praha 6, Czech Republic (hronp / vscht.cz)S

Chemistry in nanoscale as a part of material and chemical sciences deals with development of methods for preparation of nanoscale materials in leakers and layers of microleaker materials. A typical example of nanotechnology is a problem of polymer nanocomposites which has attracted attention of scientists dealing with improving polymer properties.

Recently, polymer-clay nanocomposites have attracted strong research and commercial interest due to profound improvements in material properties using a clay, which consist of silicate planar layers 1 nm thick and attracted with van der Waals forces. In general, the application of clays in polymers leads to an improvement in material properties (increased tensile strength, modulus, heat resistance, and reduced gas permeability).

The studied materials were prepared via "In situ" polymerisation of cyclic oligomers in the presence of fillers (or nanofillers) and via homogenisation of fillers and silicone rubber using mixing on a three-roll mill.

The apparent viscosity depended on shear rate was measured after the synthesis. Using the surface modified montmorillonites, compounds with different values of the apparent viscosity were prepared. Some mixtures were submitted to heating and it was measured the influence of the higher temperature on the apparent viscosity. The thermogravimetric analysis was used for determination of the stability of the mixtures and their particular components. The samples were vulcanised and the vulcanisates were used for measuring of mechanical properties and for determination of the structure of composites using X-ray diffraction.

PC80

QUANTITATIVE CHARACTERIZATION OF THE STRUCTURE OF PP/LAYERED SILICATE NANOCOMPOSITES AT VARIOUS LENGTH SCALES

Z. Dominkovics, K. Renner, B. Pukánszky Jr., B. Pukánszky

Laboratory of Plastics and Rubber Technology, Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, H-1521 Budapest, P.O.Box 91, Hungary

Institute of Materials and Environmental Chemistry, Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 17, Hungary

Layered silicate polymer composites attracted much interest recently because of their potential advantages. They are claimed to have improved thermal and dimensional stability, better barrier properties, and flame resistance than the unfilled polymer matrix. One of the main advantages of fillers dispersed on the nanoscale in polymers is claimed to be the large reinforcement reached at very low filler content, which should lead to light composites with considerable stiffness and strength. However, to really utilize all the potential advantages of polymer/layered silicate nanocomposites, the silicate must be exfoliated to a large extent into individual layers. For optimum performance the platelets should be distributed uniformly with an orientation parallel to the external load and adhere strongly to the polymer for efficient stress transfer. Unfortunately, usually none of these conditions are satisfactorily fulfilled and the theoretical reinforcing effect of the silicate is not reached as a consequence. Exfoliation is practically never complete. The majority of the papers published on these materials indicate the formation of an intercalated/partially exfoliated structure.

The structure and rheological properties of a large number of layered silicate polypropylene nanocomposites were studied with widely varying compositions. Unlike general practice, morphology was characterization at different length scales covering several decades by SEM, TEM, and XRD. Rheological measurements supplied additional information about structure. The results showed that these materials possess a very complex structural architecture. The introduction of a functionalized polymer decreases the size of the original clay. However, relatively large silicate particles were found also in composite samples yielding XRD traces without silicate reflection. XRD supplies information of limited value if silicate content is small, the gallery distance of the stacks is large or their regularity is low. On the other hand, XRD characterizes intercalation well. Although exfoliated individual layers can be detected by TEM, the method cannot be used to draw general conclusions about the overall the structure of layered silicate nanocomposites because of statistical sampling and bias. A large number of individual layers, i.e. large extent of exfoliation, lead to the formation of a silicate network structure, which can be detected very sensitively by Cole-Cole plots of dynamic viscosity. We found that not only two (individual layers, intercalated stacks), but four morphological entities, i.e. also particles and a silicate network, may be present simultaneously in the composites. Their presence and relative amount must definitely influence composite properties. However, currently used experimental protocols do not supply sufficient information even to estimate the relative influence as well as interplay among different structural features. An attempt was made to characterize morphology quantitatively, wherever possible. SEM and TEM micrographs were evaluated by image analysis, XRD traces by curve fitting, while a model was developed to determine relaxation time from rheological measurements.

PC81

SODIUM MONTMORILLONITE INTERCALATED IN ACRYLIC COPOLYMER: A MODIFIER OF REACTIVE HOT-MELT POLYURETHANE ADHESIVES

J.H. Kim, M.S. Kim, J.Y. Jang, Y.R. Lee, H.M. Jeong

Department of Chemistry, University of Ulsan, Ulsan 680-749, Korea (hmjeong / mail.ulsan.ac.kr)

The unique properties of the nanocomposites arise from the maximized interfacial contact between the polymer and sodium montmorillonite (Na-MMT), which has a high surface-to-volume ratio, because it is composed of stacks of 1nm thick parallel lamellae with a high aspect ratio. In the nanocomposites, the segmental motions of the polymer chains are restricted due to the confinement of the polymer chains between the silicate layers as well as the silicate surface-polymer interaction in the nanostructured composites.

In this study, we prepared sodium montmorillonite (Na-MMT) intercalated with poly(ethylene glycol) methacrylate (PEGM) whose molecular weight of PEG segment is 440, and polymerized that with methyl methacrylate (MMA) and buthyl methacrylate (BMA). We utilized this polymerized material to modify the reactive hot melt polyurethane adhesive, because we anticipated that finely dispersed silicate layers can accelerate the solidification of an RHA during cooling to manifest early and enhanced development of initial bond strength.

The initial green strength and final bond strength between ABS sheet and PET fabric generally increased when 14.7 phr of polymerized acrylic copolymer was added in the adhesive. And this effect was more evident when the content of Na-MMT intercalated with PEGM (Na-MMT / PEGM) in the acrylic copolymer was increased.

PC82

Polysilanes. A new Route toward high-performance ELETRIC devices

L. Sacarescu^[1], I. Mangalagiu^[2]*, G. Sacarescu¹, M. Simionescu¹, R. Ardeleanu¹

¹ Institute of Macromolecular Chemistry "Petru Poni", Iasi, Romania

²Al.I. Cuza University of Iasi, Bd. Carol-11, 700506 IASI, Romania

Polysilanes are a specific class of conjugated polymers with intriguing optoelectronic properties originating from an unexpected s-conjugation. In the last few years these materials are subject of an intensive research work aiming to various optoelectronic applications.

In order to discover and investigate new materials with EL properties, highly reactive polysilane structures with monomodal molecular weights distribution were synthesized by a homogeneous coupling technique.

This research work started with polydiphenylsilane, a highly crystalline and insoluble material by taking advantage of its similarity with polydimethylsilane, a polymer already used in large scale production of flat panel displays. The chemical structure of polydiphenylsilane was modified to obtain both solubility in common solvents and to induce new properties by attaching of various organic segments.

Therefore it was observed that small quantities of Si-H groups lead to a highly soluble material on one side and to a further developement of new polysilanic structures on the other:

Chain fragmentation thermal control

Photo-control of conformation Hybrid redox-conjugative conduction:

This research work opens new insides in understanding the conduction mechanism within the organic semiconductors by taking into account the following advantages:

· low deposition temperature in HV-CVD technique;

· solubility in common solvents;

· formation of high quality thin films for multilayer devices;

· better opto-electronic properties due to a specific design of the new chemical structure;

· hybrid conduction mechanism with higher charge carriers mobility;

· both photo and electrochemical sensitivities;

· control of the thermo-mechanical properties and morphology of the polymer;

· control of the opto-electronic transition energy value.

· control of the electronic properties by light irradiation.

These advantages gives polysilanes the potential of exploitation in a wide area of applications with higher impact on the EL devices market: foldable-displays, cell-phones, biosensors, solar cells, computerized clothing and electronic luggage tags.

References:

1. Ishikawa M., Ohshita J., In Handbook of Organic Conductive Molecules and Polymers: Vol. 2. Conductive Polymers: Synthesis and Electrical Properties, Ed. By H.S. Nalwa, John Wiley & Sons Ltd., 1997, Chap. 15.

2. Corriu R.J.P., Devylder N., GuErin C., Henner B., Jean A., Organometallics, 13, 3194, 1994.

3. Kunai A., Toyoda E., Horata K., Ishikawa M., Organometallics, 14, 714, 1995.

4. Shaheen S. E., Brabec C. J., Padinger F., Fromherz T., Hummelen J. C., Sariciftci N. S., Appl. Phys. Lett., 78, 841, 2001.

5. Brabec C. J, Sariciftci, N. S., Hummelen, J. C., Adv. Funct. Mat., 11, 15, 2001.

6. Agosti E., Rivola M., Hernandez V., Del Zoppo M., Zerbi G., Synth. Met.,100, 101, 1999.

7. Sacarescu L., Ardeleanu R., Sacarescu G., Simionescu M., Eur. Polym. J., 40/1, 57-62, 2003.

8. Sacarescu G., Ardeleanu R., Sacarescu L., Simionescu M., J. Organomet. Chem., 685, 202, 2003.

9. L. S\c\rescu, R. Ardeleanu, G. S\c\rescu, M. Simionescu, N. Hurduc, RSC-Chemical Communications, 788, 2006.

10. a) G. Sacarescu, L. Sacarescu, R. Ardeleanu, M. Marcu, N. Voiculescu, Eur. Polym. J., 36, 2089, 2000; b) G. Sacarescu, L. Sacarescu, R. Ardeleanu, P. Kurcok, Z. Jedlinski, Macromol. Rapid Commun., 22, 6, 405, 2001.

11. V. Papaefthimiou, A. Siokou and S. Kennou, Surf. Sci., 569 (1-3): 207-218, 2004.

12. H. Ishii, K. Sugiyama, E. Ito, K. Seki, Adv. Mater., 11 (8), 605, 1999.

Aknowledgements: to Romanian Ministry of Research and Education-MATNANTECH program, grant no. 36/2005 and no. 107/2006 for financial support.

^[1] Institute of Macromolecular Chemistry "Petru Poni", Iasi, Romania;

^[2] "Al. I. Cuza" University of Iasi, Romania.

PC83

MAGNETIC IRON OXIDES AS FILLERS FOR ELASTOMERS

J. Sokołowska^a, M. Zaborski^a, M. Lipińska^a

^aTechnicalUniversity of Lodz, Institute of Polymer and Dye Technology, Stefanowskiego 12/16 Lodz 90-924, Poland (marian.zaborski / p.lodz.pl)

The properties of magnetite Fe₃O₄ and maghemite γ - Fe₂O₃ with micro- and nanometric particle size were investigated. Fe₃O₄ and γ - Fe₂O₃ were used as received from Aldrich. Surface area of Fe₃O₄ and γ - Fe₂O₃, particle size, crystal structure and tendency towards agglomeration were determined.

The composites of iron oxides and acrylonitrile rubbers were prepared. Hydrogenated (HNBR) and carboxylated (XNBR) rubber were used. Dicumyl peroxide and zinc or magnesium oxides were used as the crosslinking agents, respectively.

There was no significant influence of iron oxides on the crosslinking process. The crosslinking time increased only slightly when dicumyl peroxide was used. The same effect was observed for the crosslinking efficiency estimated from the ΔM and ν_e parameters. It is probably due to the donor character of iron oxides which decreased the ionic decomposing of the peroxide what consequently affected the crosslinking process.

Iron oxides accelerated the crosslinking process of carboxylated acrylonitrile rubber. The covalent and ionic crosslinks were created. Iron oxides were partially responsible for that. However, it seems that the effect depends on the particle size - the smaller particle size, the smaller influence was observed. This is the result of the worse dispersion of iron oxide with nanometer particle size in elastomer medium. It was found that for the reinforcing effect no less than 50 phr of iron oxides had to be used. As the result the stress at elongation 100 % or 300 % and tensile strength increased. It is interesting that the vulcanizates containing the iron oxides demonstrated high hysteresis losses. The value of W₁ - W₅ was high what indicated the ability of the filler to create its own structure in elastomer medium. It is known that the materials with such hysteresis behavior can be applied as good shock absorbers. The same effect was observed for both rubbers. No matter which crosslinking agent was used for XNBR iron oxides were found to be the active fillers. The mechanical properties of the vulcanizates were very good.

Iron oxides increased the conductivity of vulcanizates and acted as the dyes. Magnetite dyed in black, while the γ - Fe₂O₃ in reddish-brown colors. It was demonstrated that iron oxides have practical applications in elastomer technology. They could be used as fillers, dyes or substances increasing the electrical conductivity. The ferromagnetic present in elastomers generated the magnetic properties of the vulcanizates, as well.

PC84

STUDY ON THE ORGANIC - INORGANIC NANOCOMPOSITE PREPARED BY SOL - GEL METHOD FOR CORROSION-PROTECTION COATING

J. Jung, Y. Lee, D. Li, G.S. Sur^*

School Of Chemical Engineering and Technology Graduate School Yeungnam University, 214-1 Dae-Dong, GyeongSan, GyeongBuk, Republic Of Korea 712-749

In regard of today's safety requirements, in vehicle construction selected high strength materials. A kind of high strength material of up to 1650 MPa can be achieved by new process in comparison to a usual value of approximately 1100 MPa for cold formed material. During the new process the materials are heating up to high temperature. And the materials are subsequently carried over to the forming die and formed for cooling down of the materials to under room temperature. This process lead to a high-strength constructional element. A problem connected with this process is scaling of the materials surface due to a high temperature oxidation. A simple way to prevent any corrosion is the modification of the materials surface by appropriate organic or inorganic coating agents. In this study, organic-inorganic silica nanocomposites were prepared by sol-gel method for protecting a corrosion from coating agents. These coating agents protected the materials from scaling during high temperature process.

Acknowledgement : The funding of this research by the Minisrty of Commerce, Industry, and Energy through High Performance Nano Composite Program is gratefully acknowledged.

PC85

ELASTOMER COMPOSITES CONTAINING BISMUTH COMPOUNDS HAVING IMPROVED X-RAY RESISTANCE

M. Zaborski^a, J. Sokołowska^a, H. Bem^b, W. Baryń^a

^aTechnicalUniversity of Lodz, Institute of Polymer and Dye Technology, Stefanowskiego 12/16 Lodz 90-924, Poland (marian.zaborski / p.lodz.pl)

^bTechnicalUniversity of Lodz, Institute of Applied Radiation Chemistry, Żeromskiego 116 Lodz 90-924, Poland

Mechanical properties of natural rubber (NR), acrylonitrile-butadiene rubber (NBR) and styrene-butadiene rubber (SBR) vulcanizates containing bismuth oxide and bismuth vanadate were investigated. In addition, X-ray resistance of composites was estimated.

The activity of bismuth oxide and bismuth vanadate as the fillers of elastomers was studied on the base of rheometric measurements and equilibrium swelling using Wolff and Parks-Lorentz theory. It was found that pigments revealed reinforcing effect and influenced on the crosslink density of the rubbers. Moreover, bismuth oxide was more active filler than bismuth vanadate.

NR vulcanizates containing bismuth compounds exhibited the best mechanical properties. The density of composites increased with elevated concentration of the filler. However, when the amount of the filler was relatively high, this parameter was still about 2 g/cm³.

The lead equivalent was measured and X-rays screening effect of vulcanizates containing bismuth compounds was estimated. Composites with the bismuth oxide favoured X-ray absorption in higher extent in the comparison with the bismuth vanadate.

It was found that 2,7 mm thick rubber sheet containing bismuth oxide and 1 mm thick lead sheet having the same 1 m² surface exhibited identical X-ray screening properties. However, the former sheet was about 2,5 times lighter (4.62 kg versus 11.34 kg).

PC86

influence of oriented polyethylene Nanoscale structure on electrical properties of polyethylene/polypyrrolE composites

M.A. Smirnov, V.Bukoshek*, G.K. Elyashevich

Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoi pr. 31, 199004 Saint-Petersburg, Russia, (smirnov / hq.macro.ru);

*University of Ljubljana, Faculty for Natural Sciences and Engineering, 1001 Ljubljana, Slovenia

Porous anisotropic structure of linear PE was formed by uniaxial extension of extruded and subsequently annealed films. The extrusion of PE was performed using slit die at high velocity of the melt flow. According to electron microphotographs supramolecular structure of porous films surface consists of the large crystalline structural forms located perpendicular to orientation direction and connected by stressed ties with pores between them.

The films obtained at various spin draw ratios were used as supports for conducting polymer - polypyrrol (PPY) prepared by oxidative polymerization of pyrrole in situ with ferrum (III) chloride in water-methanol mixture. The composite systems prepared in this process had the anisotropic electrical properties because the structure of conducting polymer is influenced by orientation degree of PE films. The dependence of anisotropy of electrical conductivity on the orientation degree of support has been investigated. It was found that this dependence is nonlinear. It may be explained by the fact that the growth of orientation degree leads to the increase of overall porosity of PE films and, as consequence, to increase of PPY content in composite. The thicker PPY layer formed on the film surface with higher orientation degree masks the surface relief, and the effect of support on the structure of PPY layer decreases. As a result the anisotropy of PPY layer becomes lower.

Electroconductivity of PE/PPY composites reached more than 100 S/cm that is extremely high value for polymer composite systems.

The work is supported by Russian Foundation of Basic Research (Grant №07-03-00177-a) and by the Programme of Basic Research, Russian Academy of Sciences Division of Chemistry and Material Sciences, "Electroconducting and electroactive Polymers" (2006-2008).

PC87

EFFECT OF VARIOUS SILSESQIOXANES ON STRUCTURE AND THERMOMECHANICAL PROPERTIES OF EPOXY-AMINE NETWORKS

I. Amici-Kroutilová, L. Matějka, J. Pleštil, M. Šlouf

Department of Polymer Networks and Mechanical Properties, Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky sq.2, 162 06 Prague 6, Czech Republic,

kroutili / imc.cas.cz

Hybrid Inorganic/Organic (I/O) polymeric materials are nowadays at the centre of a wide interest because of their combination of the excellent features of polymers (like low cost, low weight and easiness of synthesis-processing) and the ones of the ceramic materials (like high stiffness, flame resistant and barrier properties). A very large body of work has been studying practically all the combination polymers - inorganic (or I/O) materials. This body of work has been focused mostly on nanostructured hybrid polymeric materials, as they were proven to have higher properties than their standard (microstructured) counterparts.

There are mostly two synthesis path generally used to achieve such nanostructures: 1) in-situ generation of a multiphase material from a homogeneous system, 2) modification of the material structure (also by means of copolymerisation) by ex-situ generated species.

In this research it has been used this twofold synthesis path in-situ/ex-situ on thermosetting polymer based on diglycidyl ether of Bisphenol A (DGEBA) and poly(oxypropylene)diamine (Jeffamine D2000). The main issue of this research has been thus the modification of the macromolecular structure of the epoxy-amine networks by means of nanostructuring generated by in-situ or ex-situ hybrid compounds. The goal has been to establish and study preparation-structure-properties relationships.

PC88

SIGNIFICANTLY IMPROVED ELECTRICAL CONDUCTIVITY OF PVDF/PA6/CNANOTUBE NANOCOMPOSITES BY HIGH-SHEAR PROCESSING

Y. Li, H. Shimizu

Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565 Japan (yongjin-li / aist.go.jp)

Conductive polymer composites based on insulating polymer matrix and electrically conductive filler attracted many attentions recently. The investigations of the conductive polymer composites have mainly focused on decreasing the percolation threshold for lowing cost, improving processability, and enhancing mechanical properties of the composites. In this work, poly(vinylidene fluoride) (PVDF)/polyamide 6 (PA6)/carbon naotube (CNT) nanocomposites have been prepared using a high-shear extruder processed under different screw rotation speeds. The physical properties and the morphologies of the nanocomposites have been investigated. The high-shear processed nanocomposites show a significantly improved electrical conductivity and mechanical properties as compared with those processed under low shear rate. The morphological investigation indicates that the high-shear processed PVDF/PA6/CNT nanocomposites have unique nanostructured morphologies. The CNT has been homogenously located in the PA6 phase in the co-continuous PVDF/PA6 blend and no any CNT can be found in the PVDF phase. Moreover, many PA6 nanodomains with the size of several tens nanometer are found in the PVDF phase, as shown in Fig.1. In this figure, the white part shows the PVDF phase and the grey part and particles denote the PA6 phase and nanodomains, respectively. It is considered that high-shear processing takes the critical role for the formation of the unique structure. On the one hand, the high shear processing improves the dispersion of the CNT in the PA6 phase. On the other hand, the high-shear processing enhanced the miscibility between PA6 and PVDF; the many PA6 nanodomains are formed in the PVDF phase. The unique structure of the nanocomposites prepared using high-shear processing accounts for the improved electrical and mechanical properties as compared with the same composites prepared using the normal melt mixing methods. The improved dispersion of CNT in PA6 phase can reduce the percolation threshold for electrical conductivity. Moreover, the formation of PA6 nanodomains in PVDF phase can further enhance the concentration of CNT in the PA6 phase, thereby decreasing the percolation threshold of CNT in PA6 phase. It is expected that the high-shear processed PVDF/PA6/CNT nanocomposites can be used for the bipolar plates of polymer electrolyte membrane fuel cells.

PC89

PREPARATION AND CHARACTERTIZATION OF PVDF/SIO2 NANOCOMPOSITE AS PROTON-CONDUCTING MATERIAL

C. W. Wang, C. W. Lin*
Department of Chemical Engineering, National Yunlin University of Science and Technology, 123, Sec. 3, University Road, Touliu, Yunlin,
Taiwan (lincw / yuntech.edu.tw)

The nanocomposites based on PVDF/SiO2 with proton conducting capability were prepared. The dispersive phase was synthesized by using tetraethoxysilane (TEOS) as precursor, and sulfosuccinc acid (SSA) as a crosslinking agent, to form a tight network structure and SiO2-SiO3H particles with a high porosity. 3-(trihydroxysilyl)-1- propane - sulfonic acid ((THS)pro-SO3H) is added to conduct more SO3H groups. Inorganic phase of the hybrid membrane was contributed from the condensation reactions of both TEOS and (THS)pro-SO3H, and the SO3H of the hybrid membrane was obtained from both SSA and (THS)pro-SO3H. Through the infrared spectra, the characteristic adsorption peaks indicates a success of condensation reaction between TEOS and SSA. It was also confirmed through the ²⁹Si solid-state NMR spectra that (THS)pro-SO3H was involved in the reaction, and the condensation extent of TEOS and (THS)pro-SO3H was studied. With the increase of the TEOS content, the thermal stability of the hybrid membrane can be promoted. The PVDF/SiO2-SO3H hybrid membrane exhibits proton conductivity of as high as 10^-3 Scm^-1. As water state of membranes is closely related to the proton conductivity and methanol permeability, differential scanning calorimetry (DSC) was employed to investigate the water state distribution of the hybrid membrane. The surface morphology of the membranes were investigated by using SEM, suggesting that (THS)pro-SO3H may be regarded as a pore- forming additive. Besides, a wide-angle X-ray diffraction (WAXD) was employed to investigate the crystalline behavior of the hybrid membrane.

PC90

NANOCOMPOSITES OF SEMICONDUCTOR NANOPARTICLES IN SAGO STARCH: PREPARATION, STRUCTURAL AND OPTICAL PROPERTIES

D. K. Božanić^a, V. Djoković^a, P. Sreekumari Nair^b, M. K. Georges^c, T. Radhakrishnan^c

^a Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade, Serbia

^bDepartment of Chemistry Lash-Miller Chemical Laboratories, University of Toronto, Ontario, M5S 3H6. Canada

^cDepartment of Chemistry, University of Toronto at Mississauga, Mississauga, Ontario, Canada, L5L 1C6

The nanocomposites of lead sulfide (PbS) and cadmium selenide (CdSe) in a sago starch biopolymer matrix have been synthesized and investigated. The X- ray diffraction analysis of the PbS-sago starch nanocomposite exhibited strong diffraction maxima that correspond to the PbS cubic crystal structure. TEM micrograph of the PbS nanocomposite showed the spherical particles with narrow size distribution and an average diameter of 4 - 5 nm. In the case of CdSe-sago starch nanocomposite, monoclinic crystal structure of CdSe was found. The onset of the UV-VIS absorption spectra of the both PbS- and CdSe sago starch nanocomposite aqueous solution is blue shifted with respect to the bulk semiconductors. However, CdSe-nanocomposite showed well defined exciton shoulder.

PC91

ELECTROSPUN POLY(VINYL ALCOHOL)/COLLAGEN NANOFIBERS FOR PROTEIN DRUG DELIVERY

H.W. Lee^a, M.H. Hwang^a, J.H. Yeum^a, Y.H. Kim^b, J.T. Lee^b

^aDepartment of Advanced Organic Materials Science and Engineering, Kyungpook National University, Daegu 702-701, Republic of Korea (jhyeum / knu.ac.kr)

^bDepartment of Cosmeceutical Science, Daegu Haany University, Gyeongsangbukdo 712-715, Republic of Korea

Scaffolds based on collagen, one of the most representative extracellular matrix proteins, have been used in different tissue engineering applications and led to the development of bioengineered tissues such as blood vessels, heart valves and ligaments.

In this study, poly(vinyl alcohol) (PVA)/collagen nanofibers containing bovine serum albumin (BSA) were prepared by electrospinning PVA/collagen/BSA aqueous solutions. The protein- containing PVA/collagen nanofibers were characterized with regard to morphology, BSA loading efficiency, in vitro BSA release, and BSA stability. Furthermore, properties of the PVA/collagen/BSA solutions including viscosity, conductivity, and surface tension were measured.

With increasing PVA content, the morphology of blend nanofibers was changed from beaded fiber to uniform fiber. The protein stability study showed that BSA was protected during the electrospun nanofibers preparation and stabilized inside/outside the PVA/collagen nanofibers.

PC92

Hybrid biopolymer-silica nanocomposites fabricated by sol-gel technique

I. V. Semiletova, T. Yu. Karpenko, Yu. Shchipunov

Institute of Chemistry, Far East Department, Russian Academy of Sciences

690022 Vladivostok, Russia (semiletova / ich.dvo.ru)

A novel approach was developed for jellification of polysaccharide and protein aqueous solutions. As a silica precursor, tetrakis(2-hydroxyethyl) orthosilicate was used. It possesses a complete compatibility with biopolymers that was obvious from the absence of denaturating effect and precipitation or phase separation in the system after its mixing with biopolymer in a solution. This allowed jellifying most of practically important polysaccharides, whose do not form gels, and such protein as albumin. In addition, hybrid hydrogels were prepared with carrageenans and gelatin that can provide gel formation.

All the studied biopolymers played an important role in the sol-gel processes, catalyzing them. By this reason, the processing could be performed in a wide pH range extending from 2 to 10.

Hydrogels thus prepared were used further to fabricate xerogels and aerogels. The properties and structure of all the types of prepared nanocomposites materials were studied with the help of a dynamic rheology, differential scanning calorimetry, scanning electron microscopy and atomic force microscopy.

It was found that the biopolymers served as a template for silica generated in situ by the sol-gel processing. Biopolymer macromolecules were covered by an inorganic shell owing to silica nucleation and subsequent growth of precipitate. This was demonstrated by the atomic force microscopy. The suggested mechanism differs from that for the sol-gel processing performed with common silica precursors. The silica precipitation on biopolymer macromolecules determined the structure and properties of hybrid nanocomposites. They depended on the biopolymer type, charge and concentration as well as conformation of their macromolecules. Although the macromolecules were covered by silica shell, biopolymers did not loose their ability for conformational rearrangements. It was demonstrated in a case of hybrid nanocomposites materials with entrapped kappa- and iota-carrageenans and gelatin. These polysaccharides and protein experienced a reversible coil-to-helix transition with varying the temperature that provided a thermoreversible change in the mechanical properties of hybrid materials around the biopolymer phase transition temperature.

PC93

ASSOCIATION OF BOVINE BETA-CASEIN: EFFECT OF pH

I. Portnaya^a, R. Khalfin^b, O. Ramon^a, U. Cogan^a, D. Danino^a

^a Faculty of Biotechnology and Food Engineering, Technion - Israel Institute of Technology,TechnionCity,Haifa,32000, Technion City, Haifa, 32000, Israel. (portnaya / techunix.technion.ac.il).

^bFaculty of Chemical Engineering, Technion - Israel Institute of Technology, Technion City, Haifa, 32000, Israel.

The association of caseins into micelles determines many of the important physical and technological properties of milk. The mechanism of this association has been only partially clarified. Beta-casein is the most abundant casein. At neutral pH it is highly amphiphilic, and has a net charge of -11.5, that is concentrated mainly along the first 50 amino acids of its N-terminus. Previous studies by us and others showed that at neutral pH beta-casein self-organizes into detergent-like micelles that have an oblate shape. The critical micellar concentration (CMC), micellization enthalpy and the self-assembly mechanism were found to be dependent on the temperature and ionic strength.

In present work we studied the structure and the behavior of beta-casein below and above it's isoelectric point (pI~5.1). Our analysis shows that the net charge at low pH is greater than at pH 7, and the charge distribution is different. Nevertheless, we found that the protein remains amphiphilic and self-organizes into micelles. The shape and size of the micelles were studied by cryogenic transmission electron microscopy (cryo-TEM). Using isothermal titration calorimetry (ITC) and sedimentation equilibrium we also studied the CMC and aggregation number of the micelles as a function of temperature, pH and ionic strength. Small-angle x-ray scattering (SAXS) was used to study the conformation and radius of gyration (Rg) of the beta-casein monomers and micelles.

The thermodynamic analysis of the beta-casein association and quantitative demonstration of the process cooperativity below and above the protein's pI were performed. The micellization parameters and the driving force for the self-assembly of beta -casein at the different pH conditions are discussed.

PC94

Acrylic/Laponite nanocomposite films: Morphology and mechanical behavior

J. Faucheu¹ C. Gauthier¹, E. Bourgeat-Lami², J.-Y. Cavaillé¹

¹MATEIS, UMR CNRS 5510, INSA-Lyon, Bât. Blaise Pascal, 7 Av. Jean Capelle, 69621 Villeurbanne Cedex, France

²LCPP, UMR CNRS 140, CPE, Bât. F308, 43 Bd. Du 11 Novembre 1918, BP 2177, 69616 Villeurbanne Cedex, France

Nanoparticles with high aspect ratio has drawn increasing interest as reinforcement agents in polymeric materials. Laponite^[1] is a disc-like nanometric synthetic layered silicate. Through specific synthetic routes, different latex morphologies of nanostructured latexes can be obtained. The evaporation of water from latexes^[2] under adequate conditions of temperature and humidity lead to free standing film which mechanical properties can be evaluated through Dynamic Mechanical Analysis and tensile tests. This study aim at presenting the morphology obtained through both polymerization routes and the effect of this specific nanostructure on mechanical properties.

Figure1A: TEM image: Morphology of a nanostructured P(MMA-co-BA)/Laponite film, clay platelets (dark dashes) are located around the latex particle creating a honeycomb-like network of laponite. Scale Bar: 100nm

Figure1B: Shear Modulus vs. Temperature, latex film synthesized through two different routes (1) and (2) with different amount of laponite.

DMA experiments show a strong increase of the rubbery plateau level when laponite is present in the nanocomposite film. However differences between the synthesis routes is underlined for both the matrix and the filled polymer behavior.

Comparison of mechanical behaviors^[3] and morphologies of latexes synthesized by either route underlines the differences between polymerization mechanisms and Laponite/Polymer interactions.

^[1] Q. Sun et al., Macromol. Mater. Eng. (2004) 289: 288

^[2] P.A. Steward et al., Adv. Coll. Int. Sci. (2000) 86: 195

^[3] N. Agarwal et al. Pol. Eng. Sci. (2000) 40: 376

PC95

CO-CONTINUOUS STRUCTURE CONTROL OF BIODEGRADABLE POLYMER BLEND/CLAY NANOCOMPOSITES

L. Zhao*, Y. Li, H. Shimizu

Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Japan

Biodegradable poly(L-lactide) (PLLA)/poly(butylene succinate) (PBS) blends incorporated with an organoclay were prepared using a high-shear extruder, of which the shear condition can be controlled by the various screw rotation speeds. In this study, the morphologies of the PLLA/PBS (50/50) blends with different clay loading as well as four preparing shear conditions corresponding to the screw rotation speed of 100, 300, 600 and 1000rpm were compared. It was found that the high-shear processing is very effective for forming a wide range of the co-continuous structures, while the low-shear one is not effective for controlling the co-continuous structures. The processing method can control the co-continuous structures of the PLLA/PBS blends adding clay with vary wide dynamic range from several tens of μm to sub-μm levels. This kind of material is expected to the formation of size-matching separator or filters.

PC96

PORPHYRIN ASSEMBLIES FOR CHEMICAL Catalysis

N.M. Zhunusbekova^a, N.B. Sarova^a, J.K. Korganbaeva^a., T.K. Jumadilov^a, E.A. Bekturov^a

^a Laboratory of Physical Chemistry, A.B. Bekturov Institute of Chemical Sciences, Valikhanov Str. 106, Almaty, 050010, Kazakhstan, (znazym / mail.ru, jumadilov / mail.ru)

In recent years much attention has been focused on artificial carriers based on porphyrins. Porphyrins are π-conjugated macrocycles, which play a vital role in living organisms. They are parts of many enzymes, vitamins, the crucial role of porphyrins in hemoglobin or chlorophyll is generally known. In all these systems, porphyrins are present as metal complexes. Metal complexes of porphyrin are used as photosensitizes for photodynamic therapy of tumors because of their interaction with DNA. The catalytic capabilities make them useful as catalyst in many reactions. The searches of natural catalysts analogues have led to formation of a new catalytic system based on the nature porphyrins fixed on the synthetic polymeric carriers. In this study the catalytic properties of the complexes based on poly(acrylic acid) (PAAc), polyvinyl alcohol (PVA) and metalloporphyrins (PhpMe) were shown on the modeling oxidation reaction of oxalic acid. It was established that the presence of the catalysts led to increase of the reaction rate. It is shown, that complexes have high catalytic activity which presume their further practical application. We presently report about formation of micro particles on the surface of obtained complexes that predicts creation of nanosized composites. The observed results of different metal binding by porphyrins on the polymer will be presented. Fig.1 demonstrates optical microscope micrographs of the polymer carriers surfaces after complexation. It is seen that on the surface of polymer carriers some particles with size of approximately 30-40 μm have been achieved.

FIG.1. Optical microscope micrographs of particles (30-40 μm) on the surface of PAAc hydrogel (a) and PVA film (b) after complexation.

PC97

FORMATION OF TYPE I COLLAGEN FIBRILS FROM PORCINE DERMIS AND FISH SCALE OBSERVED BY AFM

M. Reiter^a,b, T. Ikoma^a, N. Hanagata^a, A. Roguska^a

^aBiomaterials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan, (http://www.nims.go.jp/eng/)

^bCharles University, Faculty of Mathematics and Physics, Ke Karlovu 5, CZ-128 00 Praha 2, Czech Republic (http://alma.karlov.mff.cuni.cz/biofyzika, michal.reiter / matfyz.cz)

Fish scale is promising and safe source of collagen for biomedical applications, but still a little is known about differences in fibril formation process compared to pig dermis collagen. The denaturation temperature (ca. 35 °C) of type I collagen extracted from scale of Pagrus major (Oreochromis niloticas) is lower than pig dermis collagen (42 °C) usually used for biomedical applications. The collagen fibril formation is of great importance for the design of scaffold in tissue engineering and improves the denaturation temperature at about 40°C. We observed adsorption morphologies and reassembly structures of the both kinds of collagen on hydroxyapatite (HAp), titanium, mica and platinum coated cover glass using atomic force microscopy (AFM). The nanostructures of supramolecular assembly after slowly drying in the air as well as in liquid were evaluated by tapping mode AFM. The AFM force spectroscopy allowed us to characterize collagen monomer and fibril adhesion to the substrates.