Structural unit

Abstract: The synthesis and structure of the p-hydroxybenzoic acid polymer is described. The polymer was successfully prepared from either the phenyl ester of p-hydroxybenzoic acid or from p-acetoxybenzoic acid. With highly purified acetoxybenzoic acid, single crystals of the polymer could be prepared. The structure of the polymer was determined and shown to consist of a double helix where the two chains are in a reversed head-to-tail order. The unit cell dimensions are: a = 17.8 A and c = 18.4 A, where c corresponds to the chain length with a repeat distance of three units. The mechanism of polymerization and formation of the single crystal is discussed. The polymer displays a reversible high-temperature crystalline transition at 325–360°C (not a melting point). The transition was characterized by differential thermal analysis, differential calorimetry, thermal expansion coefficient measurements, high-temperature x-ray scans, and dielectric constant determinations. Orientation of the polymer chains during fabrication and changes in the mechanism of oxidative degradation above the crystal transition are described.

Abstract: Nanoparticles of crosslinked and functionalized vinyl polymer, which can be used in particular as a reinforcing filler in a polymeric matrix, said nanoparticles being characterized in that said vinyl polymer is a copolymer of at least the following monomers, all of which are copolymerizable by free-radical polymerization: a non-aromatic vinyl monomer 'A'; - a monomer 'B' which has a functional group denoted by Z and having formula ≡Si-X, where X represents a hydroxyl or hydrolysable group; a crosslinking monomer 'C', in other words a monomer which is at least difunctional in respect of said polymerization. Said vinyl polymer is preferably a polymethacrylate, in particular a copolymer of methyl methacrylate (monomer A), trimethoxysilylpropyl methacrylate (monomer B) and ethylene glycol dimethacrylate (monomer C), which is in the form of nanobeads with a diameter of between 10 and 100 nm. By virtue of a very low density, this vinyl polymer filler enables a reduction in the weight of the polymeric compositions, especially those of elastomers, without deterioration in the reinforcement, and with a substantial reduction in hysteresis.

Abstract: A water-absorbent resin having high absorption capacity and a slight amount of water-soluble ingredients is produced by a process, which includes polymerizing a water-soluble monoethylenic unsaturated monomer in the presence of a crosslinking agent, and using a bifunctional compound represented by the following general formula 1 as the crosslinking agent; ##STR1## wherein R 1 and R 2 are a hydrogen atom or a methyl group independently, and --(X)-- is a divalent organic group combined in a straight chain type by an optional arrangement of a structural unit (A) of --(CO--CH═CH--CO--O) L -- and l=1-5, a structural unit (B) of --(CH 2 CH 2 O) m -- and m=2-100, and a structural unit (C) of --(R 3 O) n -- and n=0-20, in which R 3 is a C 3 -C 4 alkylene.