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In situ formation of stabilizers for the implementation of dispersion nitroxide mediated polymerization of MMA in supercritical carbon dioxide

机译:原位形成稳定剂,用于在超临界二氧化碳中实施分散氮氧化物介导的MMA聚合

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摘要

Controlled dispersion Nitroxide Mediated Polymerization (NMP) of methyl methacrylate (MMA) was successfully carried out for the first time in supercritical carbon dioxide (scCO2) in the presence of CO2-philic perfluorinated surfactant that was generated “in situ”. The control of the MMA polymerization relies on the strategy developed by Charleux et al. that consists of using a SG1-based alkoxyamine, i.e. the block-builder, in the presence of small amount of styrene. In a first step, CO2 soluble polyheptadecafluorodecylacrylate was prepared in scCO2 using block-builder as an alkoxyamine. In a second step, nitroxide SG1 mediated dispersion polymerization of MMA was conducted at 70°C and 300 bar in the presence of 5 w% of SG1 terminated surfactant compared to the monomer. Different monomer to alkoxyamine molar ratios were investigated in order to target different molecular weights. In each case, the monomer conversion was high (>90 %), the experimental molecular weight was in good agreement with the theoretical value and the polydispersity was narrow (Mw/Mn ~1.2). Moreover, after depressurisation of the cell, PMMA was collected as a free flowing powder consisting of small sized microspheres.
机译:甲基丙烯酸甲酯(MMA)的受控分散一氧化氮介导的聚合(NMP)在超临界二氧化碳(scCO2)中首次成功存在,且存在“原位”产生的亲CO2全氟化表面活性剂。 MMA聚合的控制依赖于Charleux等人开发的策略。它由在少量苯乙烯存在下使用基于SG1的烷氧基胺(即嵌段助洗剂)组成。第一步,使用嵌段助洗剂作为烷氧基胺,在scCO2中制备可溶于CO2的聚十七碳氟癸基丙烯酸酯。在第二步骤中,与单体相比,在5w%的SG1封端的表面活性剂存在下,在70℃和300bar下进行由硝基氧SG1介导的MMA的分散聚合。为了针对不同的分子量,研究了不同的单体与烷氧基胺的摩尔比。在每种情况下,单体转化率都很高(> 90%),实验分子量与理论值吻合良好,多分散性较窄(Mw / Mn〜1.2)。此外,在对细胞减压后,将PMMA收集为由小尺寸微球组成的自由流动的粉末。

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