The viscosimetric behaviour and the preferential solvation of syndiotactic, isotactic and atactic copolymers of methacrylic acid and benzyl methacrylate are studied in waterR-chloroethanol mixtures. The experimental results show that the presence of benzyl groups stabilizes the compact structure. In the case of the syndiotactic samples, the extent of the preferential hydration domain, which is related to the existence of the compact structure, is dependent on the composition of the copolymer. Experimental results also suggest that the presence of the benzyl groups destabilizes the inverse compact structure existing in 2-chloroethanol-rich mixtures.

The viscosimetric behaviour and the preferential solvation of poly(methacry1ic acid), (PMA, poly(1-carboxy-1-methylethylene)) and poly(2-hydroxyethyl methacrylate), (PHEMA, poly[l-(2-hydroxyethoxycarbonyl)-1 -methylethylenel) in water/2-~hloroethanol mixtures were studied. The system PHEMA/water/2chloroethanol is a typical polymer/solvent/precipitant system in which 2-chloroethanol is preferentially solvated in the whole range of solubility. On the contrary, the system PMA/water/2-chloroethanol is a typical cosolvent system which exhibits the so-called inverse adsorption. This difference is attributed to the more hydrophilic character of the carbonyl group in PMA.

The viscosimetric behaviour and the preferential solvation of syndiotactic, isotactic, and atactic poly(methacry1ic acid), [poly(l-carboxy-1-methylethylene)] are studied in water/2chloroethanol mixtures. The experimental results show that the preferential solvation of the polymer is strongly dependent on its local conformation. In the case of the syndiotactic sample, a close correlation has been established between the compact structure t coil conformational transition and the variation of the preferential and absolute solvation of the polymer by 2-chloroethanol, asserting the importance of hydrophobic interactions in the stabilization of the compact structure. Experimental data concerning the isotactic sample suggest the existence of an "inverse compact structure" in 2-chloroethanol-rich mixtures.

SUMMARY:The anionic block copolymerisation of isoprene and 2-vinylpyridine (ZVP) followed by a coordination with iron(II1) chloride, leads to thermoreversibly crosslinked copolymers. These copolymers are characterized by a low polydispersity (mw/mn z 1,l) between the coordination nodules of poly(2-vinylpyridine).The study of the swelling ratio at the equilibrium in benzene shows that such a polymeric network does not reach the equilibrium state expected from the thermodynamic analysis of the system. The presence of 2VP in the copolymer induces a screening effect which prevents the solvent diffusion through the polyisoprene network.