Porous structure of copolymers crosslinked with multifunctional (meth)acrylate monomers

Abstract

Abstract The homopolymers of the multifunctional monomers trimethylolpropane trimethacrylate (TMPMA), trimethylolpropane triacrylate (TMPA) and tetramethylolpropane tetraacrylate (TTMA) as well as the copolymers of these compounds with methyl methacrylate (MMA), butyl acrylate (BA) and vinyl acetate (VA) have been synthesized using the suspension polymerization method. A mixture of cyclohexanol and 2-ethylhexanol has been used as inert diluent in order to obtain porous materials. The amount of diluents is kept at 200 vol.% of the monomer mixture and in all copolymers the crosslinker level is 40 wt.%. All obtained polymers have porous structures. Their porosity and pore size distribution in the swollen state (water as solvent) have been measured using inverse size exclusion gel chromatography. It has been found that in copolymers crosslinked with TMPMA, methyl methacrylate mers make polymers more rigid and increase porosity. The best pore size distribution is observed for the TMPMA/MM/BA terpolymer; 75% of the porosity is due to the presence of pores bigger than 5 nm. Polymers containing BA display lower water regain and small pore volume. Copolymers crosslinked with TMPA have bimodal pore size distribution with a high percentage of small pores. Also in these polymers MMA mers make the network more rigid and porous. A similar effect is observed for VA, whereas BA results in porosity decrease. The network of tetramethylolpropane tetraacrylate is similar to the rigid homopolymer of TMPMA.