1999 рік

Copolymers of n-butylvinylether (BVE) and n-octadecylvinylether (OVE) with styrenesulphonate (SS) were obtained by micellar copolymerization in the presence of the cationic detergent CTAB. The polymerization reaction proceeds mainly in the domain of the hydrophobecontaining cationic micelles, to which SS and the initiator are attracted electrostatically. The monomer distribution along the polymer chain was found to be dependent on the ratio between the concentrations of hydrophobic monomer and surfactant [H]/[S]. At high [H]/[S] ratios block structures are formed and at the lower [H]/[S] ratios random distributions of the monomers were obtained. The structures of the copolymers were characterized by their NMR and emission spectra. The fluorescence emission of the copolymers obtained at higher [H]/[S] ratios were similar to that of PSS, whereas for those obtained at lower [H]/[S] ratios the spectra were like that of SS. q 1999 Elsevier Science Ltd.

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A copolymer of t-butyl-3a-(5-norbornene-2-carbonyloxy)-7a,12a-dihydroxy-5b-cholan-24-oate and maleic anhydride was synthesized as a matrix polymer for ArF excimer laser lithography. The polymer has an excellent transmittance at 193 nm and possesses good thermal stability up to 2558C. The resist formulated with the polymer showed better dry-etching resistance than the conventional KrF excimer laser resist for chlorine and oxygen mixed gas. A 0.15 mm line and space patterns were obtained at a dose of 18 mJ cm 22 using an ArF excimer laser stepper.

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The objective of this research was to investigate the effect of anions on the properties of soluble polyimides containing bipyridinium salt. Thus the work began with the synthesis of two new diamines: l,l’-di[4-(4-aminophenoxy) phenyll-4,4’-(1,4-phenylene)bis(2,6_diphenyl pyridinium dihydrogen phosphate) and I,1 '-di[4-(4-aminophenoxy)phenyl]-4,4’-( 1,4-phenylene)bis(2,6_diphenyl pyridinium p-toluenesulfonate). The two new diamines were polymerized with several dianhydrides to afford two new series of soluble polyimides. The polyimides have inherent viscosities that range from 0.284 to 0.449 dl g-’ in NJ+dimethylformamide at 25°C. These new polymers are soluble in polar aprotic solvents. Polymers containing H*POI show no glass transition temperature (T,) and the T,s of polymers containing p-toluenesulfonate (PTS) are around 240°C. Thermogravimetric analysis showed that the polymers began to decompose in the range from 390 to 419°C. Studies showed that the solubility, T,s, thermal stabilities, absorption in the visible region and photosensitivities of the polymers were affected by the basicity, structure, thermal stabilities and soft/hard character of the anions, respectively.

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Blends of poly(vinyl chloride) (PVC) and a liquid crystal copolyester (LCP) were prepared by injection-moulding. The LCP used was a copolyester consisting of 60 mol% p-hydroxybenzoic acid (PHB) and 40 mol% poly(ethylene terephthalate) (PET). The mechanical and thermal properties and the morphologies of these blends were investigated. The results showed that the tensile strength and modulus of the blends tend to increase with increasing LCP content for the blends containing LCP content below 15%, and they decreased significantly with further increasing LCP content. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) showed that PVC and LCP are partially miscible for the blends with LCP content < 15 wt% and miscible for the blends with LCP content > 15 wt%. The torque measurements indicated that the viscosity ratio between the LCP and PVC matrix is much smaller than unity. This implied that LCP fibrillation is likely to occur in the PVC/LCP blends. However, scanning electron microscopy (SEM) observations revealed that fine fibrils are only formed in the skin layer of the blends containing LCP content < 15 wt%. Two-phase morphology disappeared in the PVC/LCP blends containing LCP content above 15 wt% owing to the decomposition of LCP during processing.

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Nylon-610 membranes were prepared at 258C by direct immersion of various dope solutions into either formic acid/water or 1-octanol bath. Depending on the dope and bath conditions, the precipitated membranes demonstrated characteristics derived from crystallization and/ or liquid–liquid phase separation during the precipitation process. As a good dope solution was immersed in a harsh bath, e.g., water, precipitation occurred initiated by liquid–liquid phase separation. The formed membrane exhibited a cellular structure similar to that commonly observed in amorphous membranes. Alternatively, when a metastable dope (with respect to crystallization) was immersed in a soft bath containing a substantial amount of formic acid, crystallization dictated the precipitation process to yield bi-continuous, particulate membranes. Membranes with extensive macrovoids were observed, in the event that the dope contained a large amount of solvent. In the latter case, precipitation took place immediately after immersion, consistent with Strathmann and Smolder’s results for several membrane forming systems. In addition, skinless microporous membranes were prepared by precipitation of the dope solutions in a 1-octanol bath, in which precipitation occurred slowly and the formed membrane was composed of “sheaf-like” crystallites that interlocked into a homogeneous bi-continuous network .

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Polymerization of the symmetrical non-conjugated diyne, 1,6-heptadiyne, was carried out in nitrogen atmosphere with different initiators in dimethyl formamide. The course of polymerization was followed through ultraviolet–visible spectroscopy. The rate of polymerization was determined under different conditions and used for comparing the efficiency of the initiators. The poly(1,6-heptadiyne) was isolated and characterized through infrared spectroscopy, conductivity measurements and cyclic voltammetry. The electroactivity of the polymer was revealed.

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The kinetics of structure development during isothermal melt crystallization in blends containing low-molecular-weight fractions of poly(ethylene oxide) (PEO) and poly(methy1 methacrylate) (PMMA) has been investigated as a function of composition. Time-resolved synchrotron small-angle X-ray scattering, static wide-angle X-ray scattering and differential scanning calorimetry has been used. It has been found that in early stages of crystallization, PEO lamellae of the transient nonintegral folding (NIF) type in a wide range of compositions were formed. Subsequent transformation of NIF lamellae into the crystals with one-folded (1F) or extended chains (EC) has occurred through isothermal thinning or thickening. The amorphous PMMA diluent has played a decisive role in structure development. With increasing PMMA content, the induction time prior to crystal formation increased and the rates of NIF, 1F and EC crystallization decreased. Furthermore the recrystallization of the NIF crystals into either 1F or EC crystals was retarded. The addition of PMMA meant that the crystals were growing slowly in a more viscous medium and the retardation effect of the amorphous diluent on the kinetics of these processes resulted in the tendency to create stable and more perfectly ordered structures.

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The degradations of five aromatic thermoplastics, in whose repeating units various structures are linked to the same -ArCOQCOAr- moiety (where Ar ¼ 1,4-substituted phenylene and Q ¼ 3,7-substituted quinoline), were performed in dynamic heating conditions in the temperature range 35–950°C, under nitrogen flow and in static air atmosphere. Experiments under nitrogen suggested that degradations started by random chain scissions, to which branching and crosslinking superimposed at higher temperature, with the formation of residues stable up to 950°C; those in oxidative environment indicated that degradations were due to several processes which were simultaneous at low heating rate and that oxidative stages were involved, as supported by the complete weight loss before the overall temperature scanning. The apparent activation energy values associated with the first degradation stage were obtained by the Kissinger method. Results in inert atmosphere suggested that different linkages were involved in the initial chain scission processes of various polymers and that the comprehensive degradation mechanisms were different from those in air. Anomalous double Kissinger straight lines were found for one of the polymers investigated. The results were discussed and compared with those previously obtained for a similar group of aromatic polymers.

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Dielectric spectroscopy is a technique which is still hardly used for on-line characterization of polymers. In this article we describe its use at medium frequencies (between 10 Hz and 1 MHz) for on-line monitoring of the morphology of polymer blends during extrusion. A sheet extrusion die containing two electrodes, made it possible to perform the dielectric on-line analysis. A blend of a thermotropic Liquid Crystalline Polymer (LCP) dispersed in polypropylene was used to follow the change in shape and cocontinuity of the LCP phase with increasing extrusion speed. The creation of a more fibrous structure at higher shear rates was demonstrated by the dielectric technique as well as by SEM analysis. A blend of a thermotropic liquid crystalline polymer dispersed in polystyrene was chosen to study the evolution of the size of the LCP inclusions with increasing extruder speed. The Böttcher–Trukhan relation enabled us to convert the dielectric data to values of the particle size and a decrease in size with increasing shear rate was found. This was confirmed by SEM micrographs. The experiments and analysis presented in this article show that dielectric spectroscopy proves to be a valuable tool for on-line characterization of the microstructure of polymer blends.

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The influence of polyfnnctional monomers-tripropyleneglycol diacrylate (TPGDA), trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTMA), tetramethylolmethane tetracrylate (TMMT) and triallyl cyanurate (TAC)-on the structural changes of fluorocarbon terpolymer (F content 68%, H 1.4%) in the presence of an electron beam has been investigated with the help of IR spectroscopy (in the ATR mode) and sol-gel analysis. The absorbances at 1397, 1021,672 and 504 cm-', due to the C-F group, decrease on irradiation of the mixtures of fluoroelastomer and TMPTA, indicating dehydrofluorination and scission. The concentration of the double bond decreases both in the polyfunctional monomer and its blends with the polymer as a result of grafting and crosslinking. The concentration of the carbonyl group increases with radiation dose in the fluoroelastomer due to aerial oxidation. The effect of trimethylolpropane triacrylate (TMPTA) is to lower the amount of oxidation, especially at relatively higher levels. At a particular radiation dose, the behaviours of TPGDA, TMPTMA, TMMT and TAC based systems are similar to that of the TMPTA based one. The gel content increases with radiation dose. The influence of polyfunctional monomer on gel fraction is more prominent at higher concentrations, where distinct changes are observed at lower doses. At a particular level of multifunctional monomer, the gel fraction is lower for systems based on TPGDA. The ratio of chain scission to crosslinks calculated using the Charlesby-Pinner equation indicates a much higher crosslinking efficiency with polyfunctional monomer-fluorocarbon rubber matrix as compared to the control rubber.

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