Coupling polymerization of monofunctional allene derivatives with malonates bearing aryl halides moieties via π-allylpalladium complex

A novel polymerization method of allene derivatives with nucleophiles bearing aryl halide moieties (A-B type) is described. By the polymerization of hexylallene with malonates bearing an aryl iodide part, polymers consisting both of internal and exomethylene (exo) double bonds were obtained by mean of the coupling reaction of three different components in high yields. On the other hand, a polymer obtained from phenylallene was selectively composed of internal double bonds (E and Z). By the reaction of hexylallene with a malonate bearing two aryl halide moieties (A-B₂ type), a multibranched polymer was also obtained. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2097–2103, 1997     

Cationic polymerization of diglycidyl ether of Bisphenol A. II. theory

Network formation in cationic polymerization of polyepoxides was treated using a combination of kinetic theory and the statistical theory of branching processes (TBP). The complex reaction mechanism involved a degradative termination reaction affecting the molecular weight distribution of the primary chains. Moreover, formation of low-molecular-weight products, initiation, two mechanisms of propagation and transfer were taken into account. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 651–663, 1997     

Syntheses and radical ring-opening polymerization behavior of vinylcyclopropanone cyclic acetals having exomethylene and phenyl groups

Syntheses and radical ring-opening polymerizations of vinylcyclopropanone derivertives having cyclic six-membered acetal, exomethylene, and phenyl groups; 1-vinyl-6-methylene-4,8-dioxaspiro[2.5&]octane ( 2b ), 1-vinyl-5,7-dimethyl-6-methylene-4,8-dioxaspiro[2.5]octane ( 2c ), 1-vinyl-5-phenyl-4,8-dioxaspiro[2.5]octane ( 2d ), and 1-vinyl-5,7-diphenyl-4,8-dioxaspiro[2.5]octane ( 2e ), were carried out. The monomers were prepared by reactions of 1,1-dichloro-2-vinylcyclopropane and the corresponding diols in DMF in the presence of sodium hydride. Radical polymerizations of 2b – 2e were carried out at 60, 80, and 120°C in the presence of an appropriate initiator (3 mol % vs. monomer) in degassed sealed ampoules for 20 h. Although colorless transparent polymers (M̄_n 2300–13,500) were isolated by preparative HPLC for the most monomers, a crosslinked polymer was obtained in the case of 2b . The structures of the polymers were determined to consist of single and double ring-opening units. The content of the double ring-opened unit was 25–75% by comparison of IR spectra to a model compound. It is suggested that the double ring-opened propagating chain end is stabilized by the substituents on the cyclic acetal rings. The two-center energies of the cyclopropane ring and activation energy of ring-opening calculated by molecular orbital methods may explain the selectivity in the cleavage of the cyclopropane ring, and the degree of double ring-opening. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2501–2512, 1997     

Effect of X-ray radiation on the structure of P (VDF/TrFE) copolymers

Structural changes in poly(vinylidene fluoride)-trifluoroethylene [P(VDF-TrFE)] copolymers caused by X-ray irradiation were investigated by molecular weight determination, EPR analysis, FTIR spectroscopy, gel content, DSC thermal analysis, X-ray diffraction, and piezoelectricity measurements. Samples exhibit radiation-induced conductivity (RIC) due to the formation of radical ions. These radicals are generated by bond cleavage, which could react, leading to structural changes such as oxidation, double bond formation, chain scission, and crosslinking. The increasing gel content with radiation dose indicated that crosslinkings of the polymer chains predominate. Irradiation on P(VDF-TrFE) caused the melting temperature, heat of fusion, and Curie temperature to decrease. These results are consistent with the partial destruction of crystalline domains. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1201–1205, 1997     

Preparation of functional polymers by living anionic polymerization: Polymerization of allyl methacrylate

The anionic polymerization of allyl methacrylate was carried out in tetrahydrofuran, both in the presence and in the absence of LiCl, with a variety of initiators, at various temperatures. It was found that (1,1-diphenylhexyl)lithium and the living oligomers of methyl methacrylate and tert-butyl methacrylate are suitable initiators for the anionic polymerization of this monomer. The temperature should be below −30°C, even in the presence of LiCl, for the living polymerization to occur. When the polymerization proceeded at −60°C, in the presence of LiCl, with (1,1-diphenylhexyl)-lithium as initiator, the number-average molecular weight of the polymer was directly proportional to the monomer conversion and monodisperse poly(allyl methacrylate)s with high molecular weights were obtained. ¹H-NMR and FT-IR indicated that the α CC double bond of the monomer was selectively polymerized and that the allyl group remained unreacted. The prepared poly(allyl methacrylate) is a functional polymer since it contains a reactive CC double bond on each repeating unit. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2901–2906, 1997     

A facile cesium fluoride-mediated synthesis of aromatic polyethers from bisphenols and activated aromatic dihalides

A facile method for the synthesis of high-molecular-weight aromatic polyethers was developed with the use of cesium fluoride as a base. The high-temperature solution polycondensation between bisphenols and activated aromatic dihalides with cesium fluoride in polar aprotic solvents readily afforded a series of aromatic polyethers having inherent viscosities of 0.5–1.0 dL/g under essentially neutral and milder reaction conditions, compared with the conventinal method using alkali hydroxides or alkali carbonates. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2055–2061, 1997     

Photogenerated base in polymer curing and imaging: Design of reactive styrenic copolymers susceptible to a base-catalyzed β-elimination

A novel family of functionalized styrenic copolymers that are susceptible to a base-catalyzed β-elimination reaction is reported. The reactive copolymers, poly-{(2-phenyl-2-cyanoethoxycarbonyloxystyrene)-co-(4-hydroxystyrene)}, are prepared by chemical modification of poly(4-hydroxystyrene) using 2-phenyl-2-cyanoethyl chloroformate. A photoresist material consisting of the copolymer and bis[[(2-nitrobenzyl)-oxy] carbonyl]-4,4′-trimethylenedipiperidine used as an amine photogenerator affords positive tone images by UV irradiation. The effect of copolymer structure and composition on imaging, thermal stability, and the ease of β-elimination reaction is discussed. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3543–3552 1997     

Thermosensitive and redox-active polymers: Preparation and properties of poly(N-ethylacrylamide-co-vinylferrocene) and poly(N,N-diethylacrylamide-co-vinylferrocene)

Thermosensitive and redox-active polymers were prepared by copolymerization of N-ethyl- or N,N-diethylacrylamides with vinylferrocene (VFc). LCST (lower critical solution temperature) of the aqueous copolymer solution was decreased by increasing the ferrocene content in the copolymer. The oxidation of ferrocene led to a significant increase in LCST due to the transition from hydrophobic to hydrophilic character of the ferrocene moiety in the copolymer. The ferrocene content in the copolymer increases with increasing differences between the LCST's of the oxidation and reduction states. The transition could be made reversible by redox reaction using L -ascorbic acid as an oxidant and cerium sulfate as a reductant. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1967–1972, 1997     

Chromatography of functional polymers: A new approach to the characterization of reactive polymers obtained by chemical modification

High-performance liquid chromatography (HPLC) has been used to complement size-exclusion (gel permeation) chromatography (SEC) for the characterization of functional polymers. Whereas SEC is unable to detect compositional changes, HPLC in an appropriate interacting medium can provide detailed information on compositional changes occurring during chemical modification of a polymer. The method has been demonstrated using a normal-phase column consisting of porous monodisperse 10 μm poly(2,3-dihydroxypropyl methacrylate-co-ethylene dimethacrylate) beads that have a homogeneous coverage of aliphatic hydroxyl groups for the analysis of brominated poly(isobutylene-co-4-methylstyrene). Differences of well below 1 mol % of bromomethylstyrene units are easily detected and quantified. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1173–1180, 1997     

Speckle reduction in the small-angle light scattering technique using sample vibration

Experimental patterns obtained using the small-angle light scattering technique for thin-film polymer studies are fraught with speckles arising from the effect of interspherulitic interference. The presence of speckles hampers efforts in characterizing the spherulitic structure. Using a divergent beam increases the number of scattering sites and results in a reduction of the degree of speckling. Nevertheless, this decimates the ability of analyzing the pattern at low-scattering angles. Employing an expanded collimated beam produces the same effect but necessitates the use of specially designed optical components. This article outlines a novel technique that involves simple vibration of the polymer sample. Experimental results confirm its efficacy in reducing speckles without limiting the ability for analysis at low-scattering angles. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 937–943, 1997     

Poly(methylphenyl) silane: Structural properties

The physical structure of poly(methylphenyl) silane (PMPS) has been investigated using wide-angle x-ray scattering at various temperatures and optical polarizing microscopy. The results obtained by these techniques clearly show the existence of an ordered phase in PMPS. The crystallinity of our sample was estimated to be about 10% at room temperature. Below 190°C, the atactic chains pack into a monoclinic crystalline lattice of near hexagonal symmetry, with two types of disorder existing in the packing. At about 190°C, a phase transition to a liquid crystalline columnar hexagonal packing (D_ho) occurs. Finally, the sample melts into an isotropic amorphous phase. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1727–1736, 1997     

Evaluation by Fourier Transform Infrared Spectroscopy of the different crystalline forms in syndiotactic polystyrene samples

Fourier transform infrared (FTIR) spectra of syndiotactic polystyrene (s-PS) semicrystalline samples have been examined by using the spectral subtraction approach. For the crystalline forms including trans-planar chains (trigonal α and orthorhombic β) a number of conformational and structural order effects, not previously described in the literature, have been identified. A method based on the results of the spectral subtraction analysis has been developed for the determination of the crystallinity degree and compared with the standard method based on the wide-angle X-ray diffraction patterns. The spectral subtraction analysis on FTIR spectra allows also an easy evaluation of the amount of α and β crystalline phases (often simultaneously present in melt-crystallized samples) although both contain chains in a same conformation. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1055–1066, 1997     

Observations on the thermoreversible gelation of two-directional arborols in water–methanol mixtures

Reversible gels of two-directional cascade polymers with hydrophilic groups covalently attached by an hydrophobic center chain were studied by light and small-angle X-ray scattering, differential scanning calorimetry, and freeze-fracture transmission electron microscopy. The long, self-assembled fibers interact side-by-side over extended regions to form bundles. A given fiber may participate in several bundles, thus forming a three-dimensional gel network. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2787–2793, 1997     

Polyesters containing sulfur. V. Preparation and characterization of new polyester–sulfur compositions

New polyester–sulfur compositions with increased tensile strength were obtained by using new thiopolyesters crosslinkable with sulfur, derived from diphenylmethane-4,4′-di(methylthiopropionic acid) and ethanediol (E-P) or 2,2′-oxydiethanol (ODE-P). Such characteristics as hardness, tensile, thermomechanical, as well as some electrical properties were determined. The structure of these compositions was investigated by solid-state ¹³C-NMR spectroscopy. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2231–2238, 1997     

Synthesis,polymerization, and isomerization of isoimide containing acrylate esters

Several isoimides substituted with hydroxylated substituents were prepared, and allowed to react with acryloyl chloride to form the corresponding acrylate esters. The acrylates were polymerized free radically using AIBN as the initiator yielding medium molecular weight polyacrylates. Upon warming the prepared polyacrylates or treatment with base most of the isoimide pending groups rearranged to the stable form of the corresponding imides. These rearrangements were accompanied by increase in softening points of the polymers forming thermally more stable resins. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3125–3130, 1997     

Gas sorption and diffusion processes in polymer matrices at high pressures

A theoretical approach has been developed to describe the processes of gases diffusion and sorption in rubbery and glassy polymers. Various models (Flory-Huggins, dual-mode sorption, gas-polymer-matrix) used for interpreting the sorption-diffusion experiments are discussed within this approach framework. Experimental data on carbon dioxide sorption in glassy and rubbery polymers have been considered using the proposed approach. The comparison of the experimental and theoretical data has permitted to make the conclusion on the developed concepts adequacy. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1339–1348, 1997     

Laser-irradiation-induced surface graft polymerization method

A laser-induced surface graft polymerization method is reported in which surface radicals generated upon laser irradiation initiated radical polymerization. The radical concentrations generated upon excimer laser irradiation under vacuum on poly-(ethylene terephthalate) film surfaces were measured using a radical scavenger, 1,1-diphenyl-2-picrylhydrazyl. The density of surface radicals increased with laser fluence at low fluences but decreased at high fluences. Upon laser irradiation and subsequent treatment with gaseous N,N-dimethylacrylamide, surface graft polymerization occurred. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 747–750, 1997     

Mechanical and thermo‐mechanical studies of double networks based on thermoplastic elastomers

A new approach to prepare and characterize double network elastomeric systems was investigated. A styrene‐ethylene‐co‐butylene‐styrene (SEBS) triblock copolymer system containing physical crosslinks was used to achieve a double network by additional crosslinking using ultra‐violet (UV) light. An ethylene–propylene–diene monomer (EPDM) terpolymer system containing chemical crosslinks was used to achieve a conventional double network using UV crosslinking. Properties from conventional monotonic tensile tests, dynamic mechanical analysis, and thermomechanical properties were investigated. These double network elastomers show a transition between competitive and collaborative behavior in their mechanical properties and lower coefficients of thermal expansion arising from a competition of the networks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 778–789, 2010     

Effect of the number of seed polymer particles on the kinetic behavior of the seeded emulsion copolymerization of styrene and acrylamide

The seeded emulsion copolymerizations of styrene and acrylamide were carried out at 50°C using polystyrene latex particles as the seed and potassium persulfate as the initiator, respectively. It was found that the change in the number of seed particles initially charged causes a drastic change in the kinetic behavior of this seeded emulsion copolymerization system: when the number of seed particles initially charged was less than a certain critical value, both styrene and acrylamide started polymerization from the beginning of the reaction. However, when the number of seed particles was higher than this critical value, an apparent induction period suddenly emerged only for acrylamide polymerization, that is, acrylamide did not start polymerization until the styrene conversion exceeded around 75%, while the styrene polymerization started and continued very smoothly from the beginning of the reaction. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2689–2695, 1997