Liu Yunhe,Fang Xiya,Feng Zongze,Zhang Xiaotao,Wang Honggen,Shi Yan
Herein, we developed a reversible complexation mediated polymerization (RCMP) starting with a complex of iodine and organic salt as a deactivator and a thermal initiator for continuous regeneration of the organic salt activator. This novel polymerization method can be called as initiators for continuous activator regeneration (ICAR) RCMP, as inspired by the denomination of ICAR ATRP. The synthesis of poly (methyl methacrylate) (PMMA) ( M w / M n < 1.3) with good controllability was achieved via this technique when the concentration of the deactivator complex was as low as dozens of ppm. The studied three kinds of iodine complexes showed high control on the polymerization of MMA. The effects of initiator and deactivator complex concentration on the polymerization process were researched in detail. Furthermore, the accessibility of PMMA prepared by ICAR RCMP to chain extension and block copolymerization confirmed that this novel polymerization approach afforded polymers with high chain-end fidelity. The substantial decrease in the concentration of deactivator complex or activator plays a critical role for the production and application of well-defined polymer prepared by this method.
The reversible complexation mediated polymerization (RCMP) of methyl methacrylate catalyzed by tetrabutylammonium iodide (BNI) was performed in toluene with an alkyl iodide initiator in situ formed. The influence of BNI amount, polymerization temperature, solvent, and initiator on the polymerization was studied. Results showed that the more organic catalyst, higher reaction temperature, highly polar solvent, and higher activity initiator led to shorter inhibition period and faster polymerization. More importantly, the mechanism for the shorter inhibition period and faster polymerization with BNI was proposed:
Poly(methyl methacrylate) with predetermined molar mass and relatively low Mw/Mn (determined by size exclusion chromatography, SEC) was successfully synthesized. Furthermore, the structure of resulting polymers was characterized using 1H NMR The living/controlled feature of the polymers was further demonstrated by the chain extension experiment. Attractive features of this procedure include commercially available catalyst, ease of operation, and efficiency.
A styrene derivative, 4-N,N-dimethylaminostyrene (MAS), serving as both catalyst and monomer was exploited in reversible complexation mediated polymerization (RCMP). Radical trap experiment and UV–vis spectroscopy analysis revealed that MAS as a catalyst could abstract iodine from iodine-containing compound to generate propagating radical species. Kinetic studies demonstrated that the polymerization of styrene in the presence of MAS proceeded in a “living”/controlled manner, affording polymers with controlled molecular weights and narrow molecular weight distributions. The livingness of the obtained polymer was confirmed by chain extension. Determined by water contact angle measurement, incorporation of MAS into the polymer led to the enhancement of surface energy. Moreover, using α,ω-bis(2-iodo-2-phenylacetoxy)-end functionalized cis -1,4-polyisoprene as a macroinitiator which was synthesized through cross-metathesis of cis -1,4-polyisoprene with cis -1, 4-bis(2-iodo-2-phenylacetoxy)-2-butene, the polymerization of styrene in the presence of MAS also exhibited typical features of “living”/controlled radical polymerization to yield polystyrene-block-polyisoprene-block-polystyrene.
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