POROUS COPOLYMERS OF TRIMETHYLOLPROPANE TRIACRYLATE AND ACRYLONITRILE

The homopolymer of trimethylolpropane triacrylate (TMPA) was synthesiz ed by suspension polymerization using a thermodynamically good solvent (toluene) as a porogen (vol. ratio 1:1). This polymer possesses a hig h specific surface area (437 m2.g-1) and porosity (50%). It was found by sorption of benzene and cyclohexane that the majority of the pores are in the range of 1-5 nm. Sorption of phenol, a standard sorbate, fr om a water solution is proportional to the specific surface area of th e mesopores. This sorption is higher than that of nonspecific sorbents (like styrene/divinylbenzene copolymers) and smaller than the sorptio n of specific ones (like acrylonitrile/divinylbenzene copolymers). Two sets of reactive copolymers were obtained. In the first set, TMPA (20 -40 vol.-%) was polymerized with acrylonitrile (AN) in the presence of a constant amount of toluene as an inert diluent (vol. ratio 1:1). In the second set of copolymers the cross-linking degree was kept consta nt (30 or 40 vol.-% of TMPA) but various solvent mixtures were used, n amely: toluene/tetradecane or hexadecane, toluene/2-ethylhexanol, cycl ohexanol/tetradecane or hexadecane, cyclohexanol/2-ethythexanol (vol. ratio 9:1). It was found that all the copolymers are macroporous (volu me of pores approx. 1,0 cm3.g-1) but those obtained in the presence of good solvents display a higher specific surface area and hence better sorption properties towards phenol than those obtained in the presenc e of poor solvents. The swelling of AN/TMPA copolymers is smaller than that of the TMPA homopolymer due to the presence of additional physic al crosslinks formed by the strongly polar nitrile groups.