Growth Mechanism of Poly(divinylbenzene) Microspheres in Precipitation Polymerization

Abstract

The residual surface vinyl groups in poly(divinylbenzene) microspheres prepared by precipitation polymerization in acetonitrile were converted to hexyl groups by treatment with n-butyllithium and to ethyl groups by catalytic hydrogenation in the presence of Wilkinson's catalyst. These modified particles and unmodified particles were used as seeds in separate precipitation polymerizations of divinylbenzene in acetonitrile, under identical conditions. Only the unmodified seeds were able to capture the oligomers formed and grow without secondary initiation. Both the butylated and the hydrogenated samples showed extensive secondary initiation instead of seed particle growth. These results demonstrate that precipitation polymerization of divinylbenzene in near-ϑ solvents is an entropic precipitation, involving radical reactions between the macromonomer particles and newly formed oligomers. These results further imply that the growing particles are autostabilized by the transient solvent-swollen gel layer on their surfaces, formed by a recently captured oligomer.

Ambient temperature synthesis of well‐defined microspheres via precipitation polymerization initiated by UV‐irradiation

“…8 Interestingly, poly(DVB) microspheres synthesized via this method contain significant residual vinyl bonds in the particle and on the surface of the particle. 9 The microspheres also have a thin surface layer consisting of lightly crosslinked and swellable poly(DVB). 10 Both DVB containing 55% (DVB55) and 80% (DVB80) can be employed for the synthesis of microspheres; DVB55 results in microspheres with a slightly thicker, lightly crosslinked surface layer than DVB80 because of the lower content of DVB in DVB55.…”

Quantitative Compositional Mapping of Core−Shell Polymer Microspheres by Soft X-ray Spectromicroscopy

“…Not clear from such TEM images is the exact composition of the shell and whether the apparent contrast between core and shell is in part due to the presence of porosity in either core or shell. [34][35][36] 2.3. Scanning Transmission X-ray Microscopy (STXM) Measurements.…”

Smart surface imprinting polymer nanospheres for selective recognition and separation of glycoprotein

“…It is worth noting that we introduced boronic acid groups that can covalently interact with the template OB before the imprinting polymerization, thus making the template fixed accurately and leaving more uniform binding sites with exact spatial arrangement. Moreover, there are a certain number of residual vinyl groups on the surface of the b-PMMA spheres [39], so without any further modification, the as-synthesized b-PMMA spheres can be used as the seeds directly for NIPAAm and AAm copolymerization in the presence of the template OB by precipitation polymerization to prepare the core-shell molecular imprinting nanospheres.…”