Comparison of the effect of pore architecture and bead size on the extent of plasmachemical amine functionalisation of poly(styrene-co-divinylbenzene) permanently porous resins

Poly(styrene-co-divinylbenzene) (PS/DVB) permanently porous resins suitable for plasmachemical modification with allylamine were prepared by suspension polymerisation. Experimental design methods were employed to investigate simultaneously the influence of crosslinker content, porogen type and porogen level on the surface area, pore volume and pore diameter of the resins. From this, it was found that the porogen has a greater influence than the crosslinker. Variation of porogen type and level while keeping crosslinker level constant then lead to the maximisation of each parameter of interest, resulting in a set of samples with a wide range of values. Six samples were then chosen, representing high and low values of each property, and were subjected to plasmachemical modification with allylamine. It was found that pore volume had the greatest influence on the extent of modification. However, subsequent experiments indicated that the extent of modification is much greater for smaller beads. It is concluded that plasmachemical functionalisation occurs mainly on the external surface of the beads.