New Macroporous Crosslinked Polymer Gels Prepared via Living Radical Polymerization
- PDF / 2,281,610 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 14 Downloads / 208 Views
0947-A03-27
New Macroporous Crosslinked Polymer Gels Prepared via Living Radical Polymerization Kazuyoshi Kanamori, Kazuki Nakanishi, and Teiichi Hanada Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyoku, Kyoto, 606-8502, Japan
ABSTRACT Macroporous crosslinked polymer gels have been prepared via TEMPO-mediated living radical polymerization of divinylbenzene (DVB) in a solvent with a counter polymer. Incorporating a counter polymer, poly(dimethylsiloxane) (PDMS), induced macroscopic spinodal-type phase separation during the course of polymerization of DVB while suppressing the segregation of DVB-derived particles from the solution by living polymerization. Welldefined macroporous morphologies comprising continuous DVB-derived skeletons have thus obtained. Macropore volume and diameter were independently controlled by altering the concentrations of PDMS and the solvent. Since the present polymer gels are prepared using only the multifunctional “crosslinker”, mechanical durability against bending and compression was found to be as high as inorganic ceramics with similar morphologies and porosities.
INTRODUCTION Porous polymeric materials have been used as catalytic supports, separation media, electrochemical membranes, and sacrificial templates to obtain porous materials with various compositions. Well-defined macropores are often desired especially for the applications using liquid phase reactions or interactions because the liquid transportation should be as efficient as possible. Simultaneously, accurate controllability of pore size and volume is required for above all applications in order to design the most suitable property. Various approaches to obtain porous polymer gels have been attempted so far, including templating and phase-separation methods.1-4 In the phase-separation method, monomers with appropriate ratio of crosslinkers are polymerized in a low molecular solvent called “porogen” typically via the conventional radical polymerization.2 During the course of the polymerization of monomers/crosslinkers, micrometer-sized gel particles (microgels) are segregated from the solvent by an abrupt increase of degree of polymerization (DP). 5 Consequently, micrometersized “voids” in-between segregated particles are spontaneously formed to comprise macropores. Peters et al.6 applied living radical polymerization to obtain better controllability of pores using low molecular porogens, and also found the possibility of surface derivatization using living reactive ends. In this report, a facile synthesis of polymer gels with well-defined macropores using a counter polymer to intensively induce phase separation (spinodal decomposition, SD) during living radical polymerization, is described. By combining living polymerization and a counter polymer, or “phase-separator”, the micro-particle segregation is effectively suppressed and well-defined porous morphologies developed by SD are obtained.
EXPERIMENT Divinylbenzene (DVB, 55% mixture of isomers), 1,3,5-trimethylbenzene (TMB
Data Loading...
