材料科学与化学工程学院学术报告——Multiplicity of Morphologies

发布日期:2018-09-10 作者:材料科学与化学工程学院



报告人Julia Kornfield教授

 报告人简介Kornfield教授本科与博士分别毕业于美国加州理工学院与斯坦福大学,是一位世界知名的高分子物理学家,美国加州理工学院终身教授,宁波大学包玉刚讲座教授、省千人计划专家。目前从事聚合物加工流变学、新型眼科修补材料、防爆燃料添加剂开发、用于显示和传感应用的侧基液晶聚合物以及半结晶聚合物等多领域研究。Kornfield教授发表了包括4篇《Science》文章在内的百余篇研究论文,她曾被美国化工工程师协会(AIChE)评为当代最杰出的一百位化工工程师之一,并获得了美国自然科学基金委授予的特别创新奖,总统年轻科学家奖,美国物理学会(APS)颁发的Dillon奖,美国化学学会(ACS)颁发的Unilever奖,美国流变学会颁发的 Bingham奖章等多个奖项。


报告摘要Poly(L-lactide), PLLA, is the structural material of the first clinically approved bioresorbable vascular scaffold (BVS), a promising alternative to permanent metal stents for treatment of coronary heart disease. BVSs are transient implants that support the occluded artery for 6 months, and are completely resorbed in 2 years. Clinical trials of BVSs report restoration of arterial vasomotion and elimination of serious complications such as Late Stent Thrombosis. It is remarkable that a scaffold made from PLLA, known as a brittle polymer, does not fracture when crimped onto a balloon catheter or during deployment in the artery. We used x-ray microdiffraction to discover how PLLA acquired ductile character and found that the crimping process creates localized regions of extreme anisotropy; PLLA chains in the scaffold change orientation from the hoop direction to the radial direction on micron-scale distances. This multiplicity of morphologies in the crimped scaffold works in tandem to enable a low-stress response during deployment, which avoids fracture of the PLLA hoops and leaves them with the strength needed to support the artery. Thus, the transformations of the semicrystalline PLLA microstructure during crimping explain the unexpected strength and ductility of the current BVS and point the way to thinner resorbable scaffolds in the future.