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为了探寻乳酸缩聚新过程,拓宽乳酸及乳酸缩聚的应用领域,对非催化条件下的两阶段乳酸直接缩聚进行了研究。结果表明,通过非催化条件下的直接缩聚,能够可控地合成低聚乳酸;在回流分水反应阶段,浴温、环己烷用量及乳酸投料量对12h内的反应过程无明显影响;在减压反应阶段,浴温和反应时间对产物聚合程度有明显影响;回流分水反应12h后,再回流反应12h的反应进度与减压1h的反应进度大体相当。采用两阶段非催化直接缩聚法,改变工艺参数,合成出了3聚和9聚乳酸,通过1 H-NMR证明了其结构。非催化条件下的乳酸直接缩聚提供了一条合成纯净低聚乳酸的途径,同时为将低聚乳酸作为修饰基团引入材料和功能物质的开发领域提供了合成基础。
In order to explore the new process of polycondensation of lactic acid, broaden the application field of lactic acid and polycondensation of lactic acid, direct polycondensation of lactic acid in two stages under non-catalytic conditions was studied. The results showed that oligo-lactic acid could be synthesized in a controlled manner by direct polycondensation under non-catalytic conditions. No significant effect of the reaction temperature, cyclohexane and lactic acid dosage on the reaction process within 12 h was observed During the reaction under reduced pressure, the mild reaction time and the reaction time have a significant effect on the degree of polymerization. The reaction progress of refluxing for 12h is almost the same as that of reducing pressure for 1h after refluxing for 12h. The structure of 3-poly and 9-polylactic acid was synthesized by two-stage noncatalytic direct polycondensation and the process parameters were changed. The structure was confirmed by 1 H-NMR. The direct polycondensation of lactic acid under non-catalytic conditions provides a way to synthesize pure oligolactic acid and at the same time provides a synthetic basis for the introduction of oligolactic acid as modifying group into the development of materials and functional materials.