Oral communications

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OC01

CHLORINATED GUEST ORIENTATION AND MOBILITY IN THE CLATHRATE PHASE STRUCTURE WITH SYNDIOTACTIC POLYSTYRENE.

A. R. ALBUNIA*a, G. GUERRAa, P. RIZZOa, P. MUSTOb, R. GRAFc, H. W. SPIESSc

a Dipartimento di Chimica, Università di Salerno, via S. Allende, 84081 Baronissi, Salerno, Italy

b Institute of Research and Technology of Plastic Materials, National Research Council of Italy, via Campi Flegrei 34, 80078 Pozzuoli (Na), Italy

c Max Planck Institute for Polymer Research, Postfach 3148, D-55021 Mainz, Germany

The d form of syndiotactic polystyrene (s-PS) is characterized by a nanoporous structure able to absorb selectively some volatile organic compounds (mainly alogenated or aromatic hydrocarbons) from different environments also when present at low concentrations, forming the corresponding clathrate forms, as shown by recent sorption studies from liquid and gas phases.1

In the clathrate phase a nearly complete conformational selectivity occurs for some chlorinated guest molecules, and the conformational equilibrium is different from that in the amorphous phase, pointing out the presence of specific host-guest interactions.2 Due to the presence of these interactions, the guest molecule should assume some preferred orientation with respect to the unit cell of the polymer host, and also the mobility should be restricted. The average position of the 1,2-dichloroethane as guest molecule in the clathrate structure has been already studied by X-ray diffraction and modeling.3,4

Now, we have obtained more information about the orientation and the mobility of not only the DCE molecule, but also other different chlorinated molecules in the clathrate phase by means of linear dichroism, using an axially oriented polymeric host, and by means of 2H NMR solid state measurements.

Both techniques show that the mobility is quite restricted, also for molecule as small as DCE. Moreover, increasing the guest molecule dimension, the mobility is sensitively decreased, allowing only some simple, geometrical motions.

[1] Manfredi, C.; Del Nobile, M. A.; Mensitieri, G.; Guerra, G.; Rapacciuolo, M. J. Polym. Sci., Polym. Sci. Phys. Ed., 1997, 35, 133.

[2] Musto, P.; Manzari, M.; Guerra, G. Macromolecules 2000.

[3] De Rosa, C.; Rizzo, P.; Ruiz de Ballesteros, O.; Petraccone, V.; Guerra, G. Polymer, 1999, 40, 2103.

[4] Guerra, G.; Milano, G.; Venditto, V.; Musto, P.; De Rosa, C.; Cavallo, L. Chem. Mat., 2000, 12, 363.


OC02

Host crystalline phase Orientation and diffusivity of guests in syndiotactic polystyrene films.

P. Rizzo*a, A.R. Albuniaa, G. Milanoa, V. Vendittoa, G. Guerraa

a Dipartimento di Chimica, Università di Salerno, Via S. Allende, 84081 Baronissi (SA), Italy

Syndiotactic polystyrene (s-PS) is a high performance thermoplastic semicrystalline material, which present a very complex polymorphic behavior (1).The nanoporous d  form, which can be obtained by suitable solvent extraction procedures on samples in all clathrate forms (2), presents the lowest density (0.977 g/cm3), since, in place of the guest molecules, it includes two identical cavities per unit cell (3). s-PS samples in the nanoporous d form rapidly absorb molecules of suitable volatile organic compounds also if they are present at very low activities (4). Sorption studies from liquids and vapors have suggested that this thermoplastic material is promising for applications in chemical separation.

Since physical properties of polymeric manufacts largely depend on molecular orientation produced by processing, the type and degree of orientation of the crystalline d nanoporous phase in syndiotactic polystyrene films, obtained by different procedures, have been characterized. For both solution cast and biaxially stretched films a high degree of uniplanar orientation, corresponding to the tendency of the ac crystallographic planes, to be parallel to the film plane has been observed and rationalized (5). According to molecular dynamics simulations of diffusion of small molecules into the d nanoporous phase (6), this uniplanar orientation would minimize the molecular diffusivity through the nanoporous crystalline phase.

References

[1] Guerra, G.; Vitagliano, V. M.; De Rosa, C.; Petraccone, V.; Corradini, P. Macromolecules 1990, 23, 1539.

[2]Reverchon, E.; Guerra, G.; Venditto, V.; J. Appl. Polym. Sci., 74, 2077, (1999)

[3]De Rosa, C; Guerra, G.; Petraccone, V.; Pirozzi, B. Macromolecules, 30, 4147, (1997)

[4]Manfredi, C.; Del Nobile, M.A.; Mensitieri, G.; Guerra, G.; Rapacciuolo M. J.Polym.Sci.,Polym.Phys.Ed., 35, 133, (1997)

[5] Rizzo, P.; Lamberti, M.; Albunia, A.; Ruiz de Ballesteros, O.; Guerra G. Macromolecules in press.

[6] Milano,G; Guerra, G; Muller Plathe, F. Chemistry of Materials in press.


OC03

SOLID STATE NMR STUDY OF INTERCALATE COMPLEXES OF POLY(ETHYLENE OXIDE) AND SMALL MOLECULES

J. SPĚVÁČEK, J. BRUS

Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 162 06 Prague 6, Czech Republic

The following two types of crystalline intercalate complexes of poly(ethylene oxide) (PEO) and small molecules were studied by the solid state NMR spectroscopy:

(i) Crystalline intercalate complexes of PEO with hydroxybenzenes (resorcinol (RES), 2-methylresorcinol (2MR), hydroquinone (HYD), 4-nitrophenol (4NP)), stabilized by hydrogen bonds, or with 1,4-dichlorobenzene: The 1H chemical shifts in CRAMPS (Combined Rotation And Multiple Pulse Spectroscopy) NMR spectra were correlated with the hydrogen bond strength as characterized by infrared spectra (OH stretching band)1. Measurements of two-dimensional 1H CRAMPS exchange spectra as function of the mixing time have been used to characterize proton distances in complexes. For all the complexes studied, a close contact between PEO and the hydroxybenzene (proton distance 0.45 nm) was found. For the PEO/4NP, PEO/2MR-b and PEO/1,4-dichlorobenzene complexes, even a closer contact (0.32 nm) between aromatic and PEO protons was detected.

(ii) PEO/LiCF3SO3 complex known as a solid polymer electrolyte2: We investigated 1H chemical shifts combining 1H CRAMPS and 1H fast-MAS (Magic Angle Spinning) NMR spectra. The obtained values were compared with those found for PEO/hydroxybenzene complexes and discussed from the point of view of the magnitude of the respective interaction. From the measurement of the polarization transfer 1H® 7Li and 1H® 13C, using frequency-switched Lee-Goldburg irradiation of 1H nuclei, the distances between 7Li or 13C nuclei in LiCF3SO3 and the nearest PEO protons were estimated.

Acknowledgment: Support of the Grant Agency of the Academy of Sciences of the Czech Republic (grant No. IAA4050209) is gratefully acknowledged. The authors thank to Prof. J.J. Point, Prof. M. Dosiere and Dr. J-F. Moulin (Université Mons-Hainaut, Belgium) who kindly provided the samples.

References:

  1. J. Spěváček, L. Paternostre, P. Damman, A.C. Draye, M. Dosiere,
  2. Macromolecules 31, 3612 (1998)
  3. J. Spěváček, J. Dybal, Macromol. Rapid Commun. 20, 435 (1999)

OC04

STRUCTURE OF THE PHYSICAL CROSS-LINKS IN SYNDIOTACTIC POLYSTYRENE GELS

C. DANIEL1, G. GUERRA1, D. ALFANO1, P.MUSTO2

1 Dipartimento di Chimica, Università di Salerno,Via S. Allende, 84081 Baronissi (SA), Italy

2 Istituto di Ricerca e Tecnologia delle Materie Plastiche (CNR),Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy

In spite of the large number of studies focussing on syndiotactic polystyrene (sPS) gels,1 the nature of the polymer rich phase forming the physical cross-links between polymer chains in sPS gels has not been clarified yet and its stoichiometry remains an open question.1b,1e

In this contribution we will report on Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction investigations (WAXD) relative to semi-crystalline clathrates and gels formed in 1-dichloroethane (DCE) and 1-chloropropane (CP) for the entire composition range from pure solvent to pure polymer. The choice of these two solvents was motivated by the possible additional information which could come from their conformational equilibrium.

From combined FTIR and WAXD investigations, it will be shown that the polymer rich phase forming the cross-link domains of sPS/DCE and sPS/CP gels is a crystalline clathrate phase characterized by larger coherent lengths along the chain axes than perpendicular to them.

References:

1. (a) M. Kobayashi, N. Nakaoki, N. Ishihara, Macromolecules 1990, 23, 78. (b) T. Roels, F. Deberdt, H. Berghmans, Macromolecules 1994, 27, 6216. (c) M. Kobayashi, T. Yoshioka, M. Imai, Y. Itoh, Macromolecules 1995, 28, 7376. (d) C. Daniel, J.M. Guenet, A. Brulet, A. Menelle, Polymer 1997, 16, 4193. (e) S. Rastogi, J.G.P. Goossens, P.J. Lemstra, Macromolecules 1998, 31, 2983.


OC05

On The Clathrate STRUCTURES Of Syndiotactic Poly(m-methylstyrene).

ORESTE TARALLO, VALERIA CALIFANO, VITTORIO PETRACCONE.

Dipartimento di Chimica, Università degli Studi di Napoli ”Federico II”, Complesso di Monte Sant’Angelo, Via Cinthia, 80126 Napoli, Italy.

tarallo@chemistry.unina.it

Clathrate crystalline forms have been found for syndiotactic polystyrene (s-PS), syndiotactic poly(p-methylstyrene) (s-PPMS) and syndiotactic poly(m-methylstyrene) (s-PMMS)[1-3]. Some possible applications of these molecular compounds like, for instance, chemical separations and water or air purification from organic molecules have been recently pointed out for s-PS[2].

As far as s-PS clathrate forms are concerned all the studied structures are very similar[3] and may be grouped in only one class where the guest molecules occupy isolated cavities delimited by the benzene rings of two adjacent enantiomorphous chains. Two different classes of clathrate forms ( and  have been instead described for s-PPMS according to the steric hindrance of the guest molecule[4]. class clathrates (including bigger guest molecules) present a structure similar to s-PS clathrates. The clathrates of the class (including smaller molecules) are instead characterized by cavities, formed by four benzene rings of a same polymer chain, positioned between two adjacent enantimorphous chains related by a 2-fold screw axis of the lattice. Such cavities are not isolated and guest molecules may interact.

In this work, a preliminary characterization of clathrate structures of syndiotactic poly(m-methylstyrene) containing guest molecules having different steric hindrance is presented. A comparison between the clathrate structures of s-PS, s-PPMS and s-PMMS is also shown.

  1. C. De Rosa, A. Buono, L. Caporaso, V. Petraccone. Macromolecules, 34, 7349 (2001).
  2. G.Guerra; G. Milano; V. Venditto, P.Musto, C. De Rosa, L. Cavallo Chem. Mater, 12, 363 (2000).
  3. (a) Y. Chatani, T. Inagaki, Y. Shimane, T Iijtsu, T. Yukimori, H. Shikuma. Polymer 34, 1620, (1993); (b) Y. Chatani, Y. Shimane, T. Inagaki, H. Shikuma. Polymer 34, 4841, (1993); (c) C. De Rosa, P. Rizzo, O. Ruiz de Ballesteros, G. Guerra, V. Petraccone. Polymer, 40, 2103 (1999).
  4. (a) A. Dell'Isola, G. Floridi, P. Rizzo, O. Ruiz de Ballestreros, V. Petraccone, Macromol. Symp. 114, 243 (1997); (b) V Petraccone, D. La Camera, L. Caporaso, C. De Rosa Macromolecules, 33, 2610 (2000); (c) V. Petraccone, D. La Camera, B. Pirozzi, P. Rizzo, C. De Rosa Macromolecules, 31, 5830 (1998); (d) D. La Camera, V. Petraccone, S. Artimagnella, O. Ruiz de Ballesteros Macromolecules, 34, 7762 (2001).

OC06

PHASE BEHAVIOR AND CRYSTALLIZATION KINETICS OF
POLY(ETHYLENE OXIDE) IN THE MELT AND IN DIFFERENT MIXTURES IN THE QUIESCENT STATE AND UNDER SHEAR

SAMY A. MADBOULY AND BERNHARD A. WOLF

Institut für Physikalische Chemie und Materialwissenschaftliches Forschungszentrum der Johannes Gutenberg-Universität Mainz, Jakob-Welder-Weg 13, D-55099 Mainz, Germany E-mail samy@pc-ak-wolf.chemie.uni-mainz.de

Liquid/solid (LS) and liquid/liquid (LL) transition temperatures were determined for tetrahydronaphthalene/poly(dimethylsiloxane-b-ethylene oxide)/poly(ethylene oxide) and its sub-systems by means of an automated device that monitors light transmittance as a function of T at different constant cooling or heating rates (Fig. 1). The time variation of the radius of PEO spherulites was observed (polarizing microscope). under isothermal conditions. A non-linear spherulite growth rate was detected for all mixture at constant PEO content (15 wt%). The LL phase separation was found to influence the crystallization morphology significantly. The isothermal crystallization kinetics of THN/COP/PEO = 40/43/17 was also studied under shear by monitoring the time dependence of the sample viscosity. The data demonstrate that the crystallization process is markedly accelerated by shear. These data and the results for the quiescent state were analyzed in terms of the Avrami equation. The exponent, which provides qualitative information about the nature of nucleation and growth, grows from the normal values (approximately 3) up to 15 at

 

Fig. 1: Light transmittance of the mixture THN/COP/PEO = 25/60/15 (wt/wt) as function of temperature;
= 0.25 °C/min


OC07

FREE ENERGY AND DIMENSIONS OF MACROMOLECULES UNDER CONFINEMENT IN POLYMER INTERCALATES

P. CIFRA, T. BLEHA,

Polymer Institute, Slovak Academy of Sciences, 842 36 Bratislava, Slovakia (upoltble@savba.sk)

Polymer systems confined on the molecular length scale display the structure and properties differing from bulk systems. Macromolecules constrained by environments include polymer inclusion compounds and polymer intercalates. In clay-based polymer intercalates the chain molecules diffuse from solutions or a melt into confining spaces formed by galleries (sheets) in layered silicates. It is believed that novel physical properties of materials can be obtained by intimate interaction between chains and a confining medium.

The effect of confinement on size and free energy of macromolecules is investigated in this paper by computer simulations. The excluded volume chains confined in a slit of the width D were generated on a cubic lattice by the Monte Carlo method. Dilute and concentrated solutions placed between neutral and attractive slit plates were examined. The regions of weak and moderate chain confinements and of pore-wall attractions were considered. As regards the chain dimensions <R2> it was found that the chain compression induced in good solvents by concentration f is enhanced in a slit relative to the bulk [1]. At all concentrations, a region was noted at intermediate slit widths, where coils are squeezed along all three axes. The chain dimensions are enhanced by increasing the polymer-wall attraction e but the presence of the squeezed-chain region is retained in this case as well.

Further, the free energy change D A/kT on penetration of molecules from a bulk solution into the sheet-like structure during the intercalation process was estimated. For repulsive slit walls, the free energy penalty due to chain confinement was found to diminish steadily by an increase of concentration [2] and therefore, polymer intercalation is enhanced by f . For attractive slit walls, the gain in the adsorption energy may offset the loss of conformational entropy and D A/kT<0. The calculations has shown that the wall attraction is controlling factor of penetration in very dilute solutions only, in the rest of the concentration scale the penetration is driven by the osmotic pressure in the bulk.

[1] P. Cifra, T. Bleha, Macromol. Theory Simul. 9, 555-563 (2000)

[2] P. Cifra, T. Bleha, Macromolecules 34, 605-613 (2001)


OC08

DEPTH PROFILING OF POLYMER FILMS BY CONFOCAL RAMAN SPECTROSCOPY

S. J. SPELLSa, H. REINECKEb, J. SACRISTÁNb, J. YARWOODa AND

C. MIJANGOSa

aMaterials Research Institute, Sheffield Hallam University, City Campus, Sheffield S1 1WB, U.K.

bInstituto de Ciencia y Tecnologia de Polimeros, CSIC, Juan de la Cierva 3, 28006 Madrid, Spain

Confocal Raman microspectroscopy has many potential applications in the study of polymer-solvent interactions, including the determination of solvent and polymer-solvent complex depth profiles. This contribution focuses on preventing the formation of polymer-solvent complexes, using surface chemical modification of PVC films. While the surface-specific nature of the film modification is easily demonstrated(1), confocal Raman measurements clearly show the effects of film refractive index: the modifier depth profile shows a lack of symmetry and the film thickness is underestimated. A spectral normalisation method is described, and this is shown to result in a modifier depth profile which is in good agreement with data obtained by Raman microspectroscopy following physical cross-sectioning of a sample. Alternative techniques for Raman depth profiling are also discussed.

(1) J. Sacristán, C. Mijangos, H. Reinecke, S.J. Spells and J. Yarwood, Macromolecules 33, 6134 (2000)


OC09

The gel-like structure of polymer in thin films : an explanation of the thickness-dependent glass transition?

Y. Grohens1, L.Hamon2, A. van der Lee3, Y.Holl4

1 Laboratoire Polymères et Procédés, Université de Bretagne Sud, Rue St-Maudé, BP 92116, 56325 Lorient Cedex, France

2 Institut de Chimie des Surfaces et Interfaces, 15, Rue J.Starcky, BP 2488, 68057 Mulhouse, France

3 Institut Européen des Membranes , Université de Montpellier II - cc 047 , 2 place E. Bataillon , 34095 Montpellier Cedex 5

4 Institut Charles Sadron, 6, rue Boussingault, 67083 Strasbourg Cedex, France.

The understanding of the origin of the thickness (h) dependent glass transition temperature, Tg(h), reported over the last decade for supported and freely standing thin polymer films, is still unclear. We have measured, using ellipsometry at variable temperature, Tg(h) for various polymers in confined geometry. We report that several factors significantly affect the Tg(h) : i) polymer microstructure (stereoregularity of poly(methyl-methacrylate) (PMMA) related to local dynamics, ii) interfacial interactions, iii) conformation of the polymer chains. These results raise many fundamental questions on the origin of the thickness dependent glass transition.

The polymer microstructure is a relevant parameter for evidenced that enthalpic factors (such as interfacial interactions which increases with temperature as shown from ATR infrared spectrocopy) but also entropic (such as particular chain conformations) might contribute to the evolution of Tg(h) measured by ellipsometry. Local chain dynamics in thin films probed by dielectric spectroscopy depends on the microstructure of the polymer and highlights the influence of the side-chain motions on the Tg(h).

Indeed, the spin-coating process, the interfacial adsorption as well as the freezing-in of non-equilibrated chain conformations caused by fast solvent evaporation result in chain local conformational which can be depicted as a gel-like structure. We suggest that the chains collapsed in a less entangled state are frozen-in in this state due to rapid solvent removal. Local conformations of PMMA chains can be related to the degree of chain entanglement which was is likely to be changed by freeze extraction from various solvents. These conclusions are consistent with oscillatory density fluctuations normal to the film surface as measured by X-ray reflectometry on stereoregular PMMA thin films.


OC10

STARCH-MODIFIED FILTERS USED FOR THE RECOVERY OF POLLUTANTS FROM WASTE WATER

F.DELVAL1), G. CRINI2), J. VEBREL1),

1) Laboratoire de Chimie des Matériaux et Interfaces ( Pôle Matériaux), UFR Sciences et Techniques, Université de Franche Comté, 16 route de Gray 25030 Besançon Cedex, France

2) Centre de Spectrométrie, Université de Franche-Comté, 16 route de Gray, 25030 Besançon Cedex, France

Two kind of crosslinked polysaccharides were prepared by reticulation of a starch-enriched flour using only epichlorohydrin or epichlorohydrin in the presence of ammonia as cross linking agent.

The reaction was optimized and the products analyzed by different techniques.

These polymers derived from an industrial by-products should be effective adsorbents for the removal of pollutants from waste water.

Adsorption isotherms, sorption capacities and kinetics of the polymers were determined by two techniques. The first is the batch method and the second involved the use of open columns in chromatography.

Several sorption studies are presented, focusing on the nature of the polymer and the structure of pollutants. The results show that these polymers exhibit good sorption capacities. The mechanism of sorption is both physical and steric adsorption in the polymer network and/or the formation of hydrogen bond and hydrophobic interactions.The regeneration of the filter is also showed.


OC11

PROPERTIES OF POLY(VINYL ALCOHOL) - POLY(ACRYLAMIDE) GRAFT COPOLYMERS DEPENDING ON THE GRAFT LENGTH.

1. REDISTRIBUTION OF HYDROGEN BONDS AND ITS INFLUENCE ON THE COPOLYMER BEHAVIOR IN AQUEOUS SOLUTION

T. ZHELTONOZHSKAYA a, O. DEMCHENKO a, I. RAKOVICH a, J.-M. GUENET b, V. SYROMYATNIKOV a

a Kiev Taras Shevchenko National University, 64 Vladimirskaya str., 01033, Kiev,

Ukraine. E-mail: zheltonozhskaya@ukr.net

b Institute Charles Sadron CNRS UPR 22 6, rue Boussingault

F-67083 STRASBOURG Cedex France

In graft copolymers, forming intramolecular polycomplexes (IntraPC) such as PVA-PAAN based on poly(vinyl alcohol) and poly(acrylamide), the system of intramolecular hydrogen bonds between the main and grafted chains and also between neighboring grafts, plays a principal role. That is why, in given work at the studying of properties of PVA-PAAN graft copolymers with variable length (or molecular weight), but constant quantity of grafted chains (N = 9), the distribution of amide groups between different H-bond structures in dependence on molecular weight of grafts Mv, were characterized first of all.

By IR spectroscopy method and by the computer processing of spectra in the amide I, amide II region on the spline method the relatively insignificant changes in the amide group distribution at the increase of Mv of grafts from 3.27× 105 to 4.3× 105, were established. At the same time, at more higher Mv values (up to 5.1× 105) the sharp redistribution of amide groups, is observed, namely: the quantity of bonds between the main and grafted chains and of trans-multimers of amide groups considerably decreases, but the length of trans-multimers sharply grows. Moreover, a number of cis-trans-multimers of amide groups slightly increases. Thus, it have been revealed the effect of ”estrangement” of grafted chains from the main chain in IntraPC (PVA-PAAN) at sufficiently high length of grafts.

By the methods of static light scattering and viscometry the state of copolymer macromolecules in aqueous solution, was studied. It was established a monotonous improvement of the thermodynamic water quality in respect of PVA-PAAN in a considered region of MvPAA increase. Unlike this the values of z-average radius of inertia, characteristic viscosity and also the number of macromolecules in associate go through a minimum at Mv = 4.3× 105 and then sharply grow at the following increase of the length of grafts. The correlation between observed effects and changes in a system of intramolecular hydrogen bonds was shown.


OC12

CONFORMATIONAL CHANGES IN AQUEOUS SOLUTIONS

OF POLY(VINYL ALCOHOL) - POLY(ACRYLAMIDE) GRAFT COPOLYMERS WITH VARIOUS QUANTITY OF GRAFTS

N. KUTSEVOLa, T. ZHELTONOZHSKAYAa, J.-M. GUENETb, N. MELNIKa,

V. SYROMYATNIKOVa

a Kiev Taras Shevchenko National University, Vladimirskaya 60, 01033 Kiev,

Ukraine. E-mail: kutsevol@ukr.net

b Institut Charles Sadron CNRS UPR 22, rue Boussingault 6, F-67083 STRASBOURG

Cedex FRANCE.

Graft copolymers with chemically complementary main and grafted chains belong to the special type of polymer compounds named as intramolecular polycomplexes (IntraPC). Conformation changes in macromolecules of such graft copolymer based on poly(vinyl alcohol) and poly(acrylamide) (PVA-PAAN) with varies quantity of PAA grafts (N) from 4 to 42, were studied.

It was established by viscometry and dynamic light scattering methods that conformational change in graft copolymer macromolecules occurs at the temperature range 298 K £ T £ 308 K. It is conformation transition from IntraPC state to segregated state (Fig.1). It is caused by destruction of intramolecular H-bonds between the main and grafted chains and different solubility of the polymer components (PVA and PAA) in aqueous solution.

«

Fig.1. Conformational changes in PVA-PAAN macromolecules. (H-bonds between PAA and PVA chains - solid line and between PAA grafts as well – broken line).

It was shown, that the depth of conformational changes in macromolecules PVA-PAAN depends on quantity of grafts. The least depth of structural changes is observed for the sample with greatest value of grafts (N=42). It was established that temperature dependences of Huggins constant and characteristic viscosity have an opposite view. Temperature range of the conformation transition practically does not depend on the IntraPC structure but are determined by IntraPC concentration in solution. Reversibility of conformation changes in PVA-PAAN macromolecules at heating and cooling was established.


OC13

POLY(2-HYDROXYETHYL METHACRYLATE)/CHITOSAN IPN MEMBRANES AS A HYDROGEL SUPPORT FOR IMMOBILIZED METAL AFFINITY CHROMATOGRAPHY

GÜLAY BAYRAMOĞLU1* AND M. YAKUP ARICA2

1Department of Chemistry, Kırıkkale University, 71450 Yahºihan Kırıkkale, Turkey

2Department of Biology, Kırıkkale University, 71450 Yahºihan Kırıkkale, Turkey

An interpenetration hydrogel networks (IPNs) in membrane form was synthesized from 2-hydroxyethyl methacrylate (HEMA) and chitosan (pHEMA/chitosan) via UV initiated photo-polymerization in the presence of an initiator ’-azoisobutyronitrile. Procion Brown MX-5BR (PB MX-5BR) was covalently attached onto IPNs membrane as a metal chelating dye-ligand and different metals ion were immobilized onto the dye-ligand to use in the immobilized metal affinity chromatography (IMAC). Immobilized-metal affinity chromatography (IMAC) is a separation technique that uses covalently bound chelating compounds on solid chromatographic supports to immobilize metal ions, which serve as affinity ligands for various proteins (1,2). The selection of the support material and its preparation constitute dominant factors affecting the chromatographic performance. Accordingly, several studies have been performed to develop novel affinity supports. Natural macromolecular materials such as agarose, dextran, cellulose and chitosan, are good affinity matrixes, but are mechanically weak and often difficult to process as membranes. Chitosan is a partially acetylated glucosamine biopolymer existing in the cell wall of some fungi such as mucorales strains. Chitosan has many useful features such as hydrophilicity, biocompatibility and anti-bacterial property. Poly(hydroxyethyl methacrylate) is a synthetic hydrogel, it possesses a high mechanical strength and resistance to many chemicals and microbial degradation. These properties are very important in its use as a support material in affinity chromatography. Much attention has been paid to improve the chemical and physical properties of hydrogels in the swollen state. The main effort focused on the introduction of a second component, a hydrophobic or hydrophilic polymer into the hydrogels to form the so-called IPNs. In order to combine useful properties of the synthetic pHEMA and natural chitosan a new IPNs matrix will be prepared from these polymers. In addition, the presence of hydroxyl and amino groups on the prepared IPNs offer an easy attachment sites for a variety of ligands.

Lysozyme adsorption capacity of dye-ligand attached membrane was 79.1 mg ml-1. Immobilisation of Fe(III) and Cu(II) ions onto dye-ligand attached membranes lead to signifant increase in the adsorption capacity, about 38% and 86% of IPNs membranes to lysozyme, respectively. Adsorbed lysozyme was desorbed up to 97% by using 1.0 M KSCN as the desorption agent. It was possible to reuse these novel IPNs metal-chelate affinity membranes without significant reduction in the protein adsorption capacities. These features make the dye-ligand and metal chelate affinity membrane very good candidate for use in metal-affinity chelate separation of proteins and would be effective in processing large volume of biological fluid containing a target protein.

1- G. Bayramoğlu and M. Y. Arica (2002). Colloids and Surfaces A: Physicochem. Eng. Aspects, 202, 41.

2-M. Y. Arica, H. Testereci and A. Denizli (1998). J. Chromatogr., 799, 83.


OC14

STRUCTURE FORMATION DURING SPINNING A LYOTROPIC RIGID-POLYMER SOLUTION via DIFFERENT CRYSTAL-SOLVATE PHASES

YIZHAK TSABBA, DMITRY M. REIN, YACHIN COHEN*

Chemical Engineering Department, Technion-Israel Institute of Technology, Haifa ISRAEL 32000

An important structural element of high-performance fibers from rigid polymers is an interconnected network of oriented microfibrils, the lateral size of which is about 10 nm. It is formed in the coagulation stage of the spinning process. We report on the microfibrillar structure of poly(p-phenylene benzobisthiazole) [PBZT] formed by two extreme coagulation processes: the usual rapid process using water as the coagulant and a much slower process induced by phosphoric acid. We review the phase behaviour of the system composed of a rigid polymer, its acid solvent and a nonsolvant (coagulant) which exhibits different crystal solvate forms. The structure of the microfibrillar network was studied by small-angle x-ray scattering and transmission electron microscopy. Slow coagulation yields better-aligned microfibrils of enhanced chain packing, but the lateral size of the microfibrils formed in both cases is similar. Heat-treatment increases the width of water-coagulated microfibrils but not the acid-coagulated ones. The observations are in accord with a diffusion-controlled nucleation and growth mechanism.

Fig. 1: The microfibrillar network formed by coagulation in water (a) and acid (b).