Laboratory of Sustainable Polymers, Department of Analytical Chemistry and Organic Chemistry , University Rovira i Virgili , Tarragona 43003 , Spain.
School of Chemistry , University of Nottingham , University Park Nottingham, NG7 2RD Nottingham , U.K.
Biomacromolecules. 2019 May 13;20(5):2135-2147. doi: 10.1021/acs.biomac.9b00435. Epub 2019 May 1.
The precise synthesis of polymers derived from alkyl lactate ester acrylates is reported for the first time. Kinetic experiments were conducted to demonstrate that Cu(0) wire-catalyzed single electron transfer-living radical polymerization (SET-LRP) in alcohols at 25 °C provides a green methodology for the LRP of this forgotten class of biobased monomers. The acrylic derivative of ethyl lactate (EL) solvent and homologous structures with methyl and n-butyl ester were polymerized with excellent control over molecular weight, molecular weight distribution, and chain-end functionality. Kinetics plots in conventional alcohols such as ethanol and methanol were first order in the monomer, with molecular weight increasing linearly with conversion. However, aqueous EL mixtures were found to be more suitable than pure EL to mediate the SET-LRP process. The near-quantitative monomer conversion and high bromine chain-end functionality, demonstrated by matrix-assisted laser desorption ionization time-of-flight analysis, further allowed the preparation of innovative biobased block copolymers containing rubbery poly(ethyl lactate acrylate) poly(ELA) sequences. For instance, the poly(ELA)- b-poly(glycerol acrylate) block copolymer self-assembled in water to form stable micelles with chiral lactic acid-derived block-forming micellar core as confirmed by the pyrene-probe-based fluorescence technique. Dynamic light scattering and transmission electron microscopy measurements revealed the nanosize spherical morphology for these biobased aggregates.
首次报道了由乳酸乙酯丙烯酸酯衍生的聚合物的精确合成。进行了动力学实验，以证明在 25°C 下，Cu(0) 丝催化的单电子转移-自由基聚合（SET-LRP）在醇中为这种被遗忘的生物基单体的 LRP 提供了一种绿色方法。乳酸乙酯（EL）的丙烯酸衍生物、甲酯和正丁酯的同系物在醇溶剂中进行聚合，具有出色的分子量控制、分子量分布和链末端官能团。在常规醇如乙醇和甲醇中的动力学图首次在单体中呈现出一级反应，分子量随转化率呈线性增加。然而，发现水相 EL 混合物比纯 EL 更适合介导 SET-LRP 过程。通过基质辅助激光解吸电离飞行时间分析证明了近乎定量的单体转化率和高溴端基官能团，进一步允许制备含有橡胶状聚（乳酸乙酯丙烯酸酯）（PELA）序列的创新型生物基嵌段共聚物。例如，聚（PELA）-b-聚（甘油丙烯酸酯）嵌段共聚物在水中自组装形成稳定的胶束，其手性乳酸衍生的胶束核通过芘探针荧光技术得到证实。动态光散射和透射电子显微镜测量表明这些生物基聚集体具有纳米级球形形态。
