Quasi-static particle formation of poly(acrylamide/methacrylic acid) in ethanol by using V-65 as initiator

Abstract

Quasi-static precipitation polymerization of acrylamide (AAm) and methacrylic acid (MAc) in ethanol by using 2,2′-azobis(2,4-diemthylvaleronitrile) (V-65) as initiator was carried out. The effects of initial concentration of initiator and monomers on the kinetics of polymerization were investigated by gravimetry, SEM and HPLC. It was observed that the number of particles was severely dependent on the total initial concentration of monomers, and less affected by the concentration of initiator. The total surface area of the particles was independent of the concentration of initiator, but slightly affected by the initial concentration of monomers. In the range investigated in this paper, the lowest initial concentration of monomers, gave the maximum number of particles, whilst the highest concentration gave the minimum number of particles, but there was no significant difference observed among the total surface area of particles prepared by using various monomer concentrations. The normalized diameter against the initial concentration of monomers was linearly simulated in the range of concentration of monomers, W₀, investigated in present system, R′ = 75.4W₀ + 149.5. After the induction period, several pairs of curves of conversion vs. polymerization time overlapped. It indicated that the variation of conversion against time mathematically related to , where C_i,0 was the initial concentration of initiator. HPLC revealed MAc was consumed faster than AAm during the polymerization and a lot of AAm remained in dry particles.