Living Radical Polymerization by Polyhedral Oligomeric Silsesquioxane-Holding Initiators:  Precision Synthesis of Tadpole-Shaped Organic/Inorganic Hybrid Polymers

Abstract

Incompletely condensed polyhedral oligomeric silsesquioxane (POSS) with the highly reactive group of trisodium silanolate was used for the synthesis of two initiators for atom transfer radical polymerization, one with a 2-bromoisobutyl group and the other with a chlorosulfonyl group. These initiators were applied to solution polymerizations of styrene and methyl methacrylate in the presence of a copper complex. In both systems, polymerization proceeded in a living fashion, as indicated by the first-order kinetics of monomer consumption, the evolution of molecular weight in direct proportion to monomer conversion, the good agreement of molecular weight with the theoretical one, and the low polydispersity, thus providing tadpole-shaped polymers with an “inorganic head” of POSS and an “organic tail” of well-defined polymer. Thermogravimetric and differential scanning calorimetric studies showed that both thermal degradation and glass transition temperatures of the organic/inorganic hybrid polymers with molecular weights up to about 20 000 were enhanced as compared to those of model polymers without the POSS moiety.

Synthesis of grafted polysilsesquioxane by ring-opening polymerization of lactide and trimethylene carbonate

“…Consequently, various combinations of polymeric components and PSQs have been investigated. [8][9][10][11][12] We have previously investigated the grafting of the biodegradable polymers e-caprolactone (CL) and L-(-)-lactide (LA) from the PSQ main chain containing phenyl and aminopropyl groups (APSQ). 13,14 In thermal analyses of the resultant PSQs, low crystallinity of the polymeric components seems to be induced by the presence of the polysiloxane structure.…”

Synthesis of thermoresponsive polysilsesquioxane with methoxyethylamide group and crown ether

“…Graft polymerizations onto and from the PSQ main chain are one of the most effective methods of making modifications, in which the polymeric component provides an additional property besides durability for heat and weatherability based on the inorganic polysiloxane backbone. [12][13][14][15][16] Among the various functions conferred on the hybrids on the basis of their polysiloxane structure, thermoresponsive phase separation in an aqueous solution is one of the useful properties. This property is required of materials used for microencapsulation, biosensors, drug delivery and so forth, as reported in a variety of recent works.…”

Preparation of Thermoresponsive Grafted Polysilsesquioxane from Polyacrylamides Having Methoxysilyl End Group

“…The graft polymerization onto and from the silsesquioxane main chain has been also recognized as an effective method for the modification, in which the polymeric component provides an additional property besides durability for heat and weatherability based on the inorganic polysiloxane backbone. [10][11][12][13][14] We also presented several reports concerning the grafted PSQ which intended to prepare a new multi-functional hybrid material. [15][16][17] The synthesis of thermoresponsive PSQs, grafted the copolymer of N,N-dimethylacrylamide (DMAA) and Nisopropylacrylamide (NIPAM), was an example utilizing the modification method.…”