Complex-radical cyclocopolymerization of allyl a-(N-maleimido)acetate with styrene and maleic anhydride

Radical copolymerizations of allyl alpha-(N-maleimido)acetate (AMI) with styrene (D, electron-donor) or maleic anhydride (A, electron-acceptor) were carried out in benzene and/or methyl ethyl ketone (MEK) at 50-70 degrees C in the presence of 2,2'-azoisobutyronitrile (AIBN) as initiator. The structure and properties of copolymers synthesized were derived from IR, chemical, DTA and TGA analyses. Side-chain unsaturation of macromolecules was also proved by the crosslinking effect observed. Kinetic parameters of copolymerization such as complex-formation (K-c), cyclization (k(cyc)), and copolymerization constants and ratios of chain growth rates for the participation of monomer charge transfer complexes (CTC) and free monomers for both systems were obtained: K-c = 0,20 +/- 0,01 and 0,05 +/- 0,005 L/mol in CH3COOH-d(4) at 35 +/- 0,1 degrees C (H-1 NMR method) for D...AMI and AMI... A complexes, respectively; k(cyc) . 10(5) = 1.71 and 0,66 L/(mol . s), r(1) = 0,13 +/- 0,01 and 0,037 +/- 0,002, r(2) = 0,048 +/- 0.002 and 0,052 +/- 0,002 (by Kelen-Tudos method), k(12)/ k(21) = 0,20 and 0,62, k(1c)/k(12) = 0,6 and 29,8, k(2c)/k(21) = 4,8 and 9,1 for the D-AMI and AMI- A systems, respectively. The results show that alternating cyclocopolymerization reactions are realized which are carried out via a ''mixed'' mechanism in the D-AMI system and via a ''complex'' mechanism in the AMI-A system, with formation of cyclolinear macromolecules containing side-chain unsaturated fragments of ''allyl'' (D-AMI copolymer) and ''imide' (AMI-A copolymer) types. The synthesized copolymers easily undergo crosslinking by thermotreatment (105 degrees C, 30 min) and/or by UV-irradiation (25 degrees C, 15 min), which was confirmed by DTA and TGA analyses

Effect of inorganic salts on the main parameters of the dilute aqueous poly(vinylpyrrolidone) solutions

The effect of inorganic salts (cosolute) on the main parameters of dilute aqueous poly(vinylpyrrolidone) (PVP) solutions, such as cloud points, phase diagram, theta temperature and viscosity was studied experimentally using various concentrations of salts and said polymer at varying temperatures. It is shown that, thermodynamic incompatibility of aqueous PVP-salts solutions strongly depends on the character of effect of salts (water-structure breakers or water-structure makers). Inclusion of salts into aqueous PVP solution leads to decreasing of the theta temperature and intrinsic viscosity which is caused by effect of the cosolute ions in enhancing the segment-segment interactions. (C) 1996 Elsevier Science Ltd