Poly(lactic acid) (PLA) is one of the most important bio-plastics, and chemical modification of the already-polymerized poly(lactic acid) chains may enable optimization of its material properties and expand its application areas. In this study, we demonstrated that poly(lactic acid) can be readily dissolved in acrylic acid at room temperature, and acrylic acid can be graft-polymerized onto poly(lactic acid) chains in solution with the help of photoinitiator benzophenone under 254 nm ultraviolet (UV) irradiation. Similar photo-grafting polymerization of acrylic acid (PAA) has only been studied before in the surface modification of polymer films. The graft ratio could be controlled by various reaction parameters, including irradiation time, benzophenone content, and monomer/polymer ratios. This photo-grafting reaction resulted in high graft ratio (graft ratio PAA/PLA up to 180%) without formation of homopolymers of acrylic acid. When the PAA/PLA graft ratio was higher than 100%, the resulting PLA-g-PAA polymer was found dispersible in water. The pros and cons of the photo-grafting reaction were also discussed.

中文翻译：

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溶液中将聚丙烯酸光接枝到聚乳酸链上

聚乳酸（PLA）是最重要的生物塑料之一，对已经聚合的聚乳酸链进行化学修饰可以优化其材料性能并扩大其应用领域。在这项研究中，我们证明了聚乳酸在室温下很容易溶解在丙烯酸中，并且可以借助光引发剂二苯甲酮在254 nm紫外线下将丙烯酸接枝聚合到溶液中的聚乳酸链上。 （UV）照射。丙烯酸（PAA）的类似光接枝聚合只是在聚合物膜的表面改性之前才进行研究。接枝率可以通过各种反应参数来控制，包括辐照时间，二苯甲酮含量和单体/聚合物比。该光接枝反应导致高的接枝率（高达180％的接枝率PAA / PLA）而没有形成丙烯酸的均聚物。当PAA / PLA接枝率高于100％时，发现所得的PLA-g-PAA聚合物可分散在水中。还讨论了光接枝反应的优缺点。