Date of Award
Program or Major
Doctor of Philosophy
W Rudolf Seitz
The polymerization of Kraton G1652 modified poly(vinylbenzyl chloride) in the presence of xylene and dodecane is complex. Scanning electron micrographs and porosimetry data suggest that as polymerization proceeds, the forming poly(vinylbenzyl chloride) and the porogenic solvent separate into distinct aromatic and aliphatic phases, respectively. The Kraton G1652 acts as a surfactant between the dodecane and the forming polymer swollen in monomer, and is directly involved in stabilizing the interface. Increasing the Kraton G1652 increases the surfactant content of the monomer mixture which decreases the surface tension between the forming polymer and the dodecane during polymerization, resulting in a morphology consisting of small poly(vinylbenzyl chloride) spheres situated throughout the aliphatic matrix. Because Kraton G1652 has a stabilizing effect, the resulting morphology is due to the drive to lower energy and therefore increase the surface area between the two phases. Removal of the porogenic solvents results in a matrix that consists of microporous poly(vinylbenzyl chloride) spheres surrounded by a "sea" of micro- and macroporous polymer.
The morphology of the matrix governs the properties of the polymer. The diameter ratio and swell time of the beads were measured in both toluene and acid. The bead formulations were further characterized by the determination of the penetration modulus, which is a measure of the mechanical strength.
The process of swelling the beads in toluene is not the same as in acid. Swelling in toluene is dependent upon the solvent's access into the bead's interior, whereas, swelling in acid is dependent upon the number of sites which were protonated throughout the matrix. Swelling time in toluene is dependent upon the pore structure of the polymer. It is not evident that the swell time in acid is dependent upon the same parameters, further indicating that the swelling processes are distinct. The penetration modulus is largely determined by the pore space present in the polymer matrix. As the volume of pore space increases, the penetration modulus decreases.
Conway, Vicki Lynn, "Polymer substrates for use in fiber optic sensors: Suspension polymerization of Kraton G1652 modified poly(vinylbenzyl chloride)" (1994). Doctoral Dissertations. 1816.