Photoinduced plasticity in cross-linked polymers
Photoinduced plasticity in cross-linked polymers
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DOI：
10.1126/science.1110505
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发表时间：
2005-06-10
期刊：
影响因子：
56.9
通讯作者：
Bowman, CN
中科院分区：
文献类型：
--
作者：
Scott, TF;Schneider, AD;Bowman, CN
化学交联的聚合物固有地受到由聚合期间的后凝胶化体积变化引入的应力的限制。在没有相应的材料性能损失或大量应力发展的情况下改变交联聚合物的形状也是困难的。我们展示了一种交联聚合物，在暴露于光下时，表现出应力和/或应变松弛，而没有任何伴随的材料性能的变化。该结果通过经由聚合物基质中的残余光引发剂的光裂解引入自由基来实现，所述自由基然后经由中链官能团的加成-断裂链转移扩散。这些过程导致光致塑性、致动和平衡形状变化而没有残余应力。这种聚合物材料对于微器件、生物材料和聚合物涂层的发展至关重要。
Chemically cross-linked polymers are inherently limited by stresses that are introduced by post-gelation volume changes during polymerization. It is also difficult to change a cross-linked polymer's shape without a corresponding loss of material properties or substantial stress development. We demonstrate a cross-linked polymer that, upon exposure to light, exhibits stress and/or strain relaxation without any concomitant change in material properties. This result is achieved by introducing radicals via photocleavage of residual photoinitiator in the polymer matrix, which then diffuse via addition-fragmentation chain transfer of midchain functional groups. These processes lead to photoinduced plasticity, actuation, and equilibrium shape changes without residual stress. Such polymeric materials are critical to the development of microdevices, biomaterials, and polymeric coatings.