Grafting from ramie fiber with poly(MMA) or poly(MA) via reversible addition-fragmentation chain transfer polymerization
Grafting from ramie fiber with poly(MMA) or poly(MA) via reversible addition-fragmentation chain transfer polymerization
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DOI：
10.1007/s10570-009-9343-8
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发表时间：
2009-12-01
期刊：
影响因子：
5.7
通讯作者：
Liu, Zhong-Wen
中科院分区：
文献类型：
--
作者：
Chen, Jing;Yi, Jie;Liu, Zhong-Wen
采用可逆加成-断裂链转移（RAFT）聚合方法，以天然苎麻纤维为基体，控制甲基丙烯酸甲酯（MMA）和丙烯酸甲酯（MA）的接枝。首先将苎麻纤维的羟基转化为2-二硫代苯甲酰基异丁酸酯作为RAFT链转移剂（CTA），然后在2-乙氧羰基丙-2-二硫代苯甲酸酯作为游离链转移剂的存在下，通过RAFT聚合将CTA与MMA或MA进一步接枝。用聚甲基丙烯酸甲酯（MMA）或聚甲基丙烯酸甲酯（MA）对苎麻纤维进行疏水改性，得到了接触角大于130 °的疏水苎麻纤维。采用重量法、傅里叶变换红外光谱、扫描电镜、差示扫描量热法、热重法和接触角法对改性后的苎麻纤维进行了分析。结果表明，苎麻纤维表面确实接枝了高分子链，平均33%的苎麻原纤维羟基被2-溴异丁酰溴取代，平均接枝率为25%。通过尺寸排阻色谱法对共聚反应中形成的均聚物进行了分析，以估算苎麻纤维表面接枝链的分子量和多分散指数，其显示出窄的多分散性，PDIs < 1.32。本研究为利用丰富的天然苎麻纤维素资源制备功能复合材料提供了一条新的可行途径。
Reversible addition-fragmentation chain transfer (RAFT) polymerization was utilized to control the grafting of methyl methacrylate (MMA) and methyl acrylate (MA) from natural ramie fibers substrate. The hydroxyl groups of ramie fibers were first converted to 2-dithiobenzoyl isobutyrate as a RAFT chain transfer agent (CTA), which was further grafted with MMA or MA mediated by the RAFT polymerization in a presence of 2-(ethoxycarbonyl)prop-2-yl dithiobenzoate as a free chain transfer agent. Hydrophobic poly(MMA) or poly(MA) modified ramie fibers with contact angles greater than 130A degrees were obtained. The modified ramie fibers were analyzed by gravimetry, Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, thermogravimetry and contact angle measurements. The results indicate that the polymer chains had indeed been grafted from the surface of the ramie fibers with an average 33% of the hydroxyl groups in the raw ramie fiber substituted by 2-bromoisobutyryl bromide and an average grafting ratio of 25% poly(MMA) or poly(MA) related to ramie fiber. The homopolymers formed in the copolymerization were also analyzed to estimate molecular weights and polydispersity indices of grafting chains from the surface of ramie fibers by size exclusion chromatography, which showed narrow polydispersity with the PDIs to be < 1.32. This study provides a novel and feasible approach to the preparation of functional composite materials for utilizing the abundant natural ramie fiber cellulose resource.