Über copolymere der p-vinylbenzolboronsäure mit styrol

The reactivity ratios of the radical solution copolymerization for the systems p-vinylbenzeneboronic acid ( 1a ) (M₁)/styrene, resp. bis(trimethylsilyl) p-vinylbenzeneboronate ( 1b ) (M₁)/styrene were determined by means of boron analyses:

• 1a: r₁=0,28±0,06 and r₂=0,83±0,04
• 1b: r₁=0,28±0,10 and r₂=0,87±0,08

By cleavage of the trimethylsilyl groups, the 1b /styrene copolymers are smoothly transformed into 1a /styrene copolymers. The lithium, sodium, and potassium salts of some copolymers were prepared. The solution viscosities of the polymeric boronic acids in benzene/methanol mixtures and in dimethyl sulfoxide (DMSO) markedly depend on the boronic acid content. In benzene/methanol mixtures the preferential solvatation of the boronic acid groups by methanol can be ascertained. Further, the introduction of boronic acid groups in polystyr-enecorresponds with an increase of theglass transition temperature. The torsion pendulum measurements show that the pressure-molding of the polymers causes the formation of crosslinks, which are boronic acid anhydrides. These crosslinks can be cleaved by protic solvents.