Controlled Radical Synthesis in Supercritical Carbon Dioxide of New Stimuli-Responsive Materials for Biomedical Applications

在这项由化学系高分子、超分子和纳米化学计划资助的项目中，加州大学圣克鲁斯分校的丽贝卡·布拉斯劳将研究超临界二氧化碳中的非均相氮氧化物介导的自由基聚合(NMRP)，并将合成定义明确的刺激响应材料。该项目是与高威爱尔兰国立大学的法瓦兹·阿尔达巴格教授和西班牙马德里聚合物科学与技术研究所的卡洛斯·埃尔维拉教授进行的三方国际合作。将合成在氮氧化物部分上具有极性或亲氟官能团(全氟烷基和聚硅氧烷基团)的氮氧化物基引发剂。在聚合过程中，这种氮氧化物部分将被用来控制增长的聚合物在超临界二氧化碳中的分配，使得单体和烷氧胺引发剂最初都是可溶的，但聚合物在临界聚合度时沉淀。添加稳定剂将允许控制最终的颗粒大小。将探索具有双重引发剂和稳定剂能力的聚合物烷氧胺在超临界二氧化碳中分散NMRP的开发。热或pH响应型聚合物将被开发用于药物输送、非病毒基因载体和用于细胞操作的表面涂层等应用。这些设计的材料将在生物兼容性研究、与DNA的络合研究以及使用不同细胞系的质粒转染水平中进行检验。更广泛的影响包括通过建立三方国际合作培训研究生和加强研究和教育基础设施。美国、爱尔兰和西班牙群体之间的协同互动将进一步扩大对这些学生的培训，在国际合作环境中促进青年科学家的学习、教学和培训，同时丰富多元文化。该项目将为绿色聚合条件在工业合成中的应用提供进一步的科学认识。二氧化碳是一种普遍存在的大气气体，作为塑料材料制造的溶剂，可以减少挥发性有机化合物(VOC)的排放。该项目还将进一步加深我们对用于生物医学应用的聚合物的基本设计原则的理解。

In this project funded by the Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division, Rebecca Braslau of the University of California at Santa Cruz will study heterogeneous nitroxide-mediated radical polymerization (NMRP) in super-critical carbon dioxide and will synthesize well-defined stimuli-responsive materials. This project is a three-way international collaboration with Prof. Fawaz Aldabbagh of the National University of Ireland in Galway and Prof. Carlos Elvira of the Institute of Polymer Science & Technology in Madrid, Spain. Nitroxide-based initiators bearing polar or fluorophilic functionalities (perfluoroalkyl and polysiloxane groups) on the nitroxide moiety will be synthesized. During polymerization this nitroxide moiety will be used to control the partitioning of the growing polymer in super-critical carbon dioxide, such that both monomer and alkoxyamine initiator are initially soluble but the polymer precipitates at a critical degree of polymerization. The addition of a stabilizer will permit control of the final particle size. The development of polymeric alkoxyamines that possess dual initiator and stabilizer capabilities for dispersion NMRP in super-critical carbon dioxide will be explored. Thermal or pH-responsive polymers will be developed for applications such as drug-delivery, non-viral gene vectors and surface coatings for cell manipulations. These designed materials will be examined in biocompatibility studies, complexation studies with DNA, as well as plasmid transfection levels using different cell lines. The broader impacts include training graduate students and enhancing infrastructure for research and education through the establishment of a trilateral international collaboration. The synergistic interactions between the American, Irish and Spanish groups will further broaden the training of these students, introducing a multicultural enrichment while promoting learning, teaching and training of young scientists in an international, collaborative environment. This project will provide further scientific understanding about using green polymerization conditions for industrial synthesis. Carbon dioxide is a ubiquitous atmospheric gas, and its use as a solvent for plastic material manufacturing could lead to a reduction in volatile organic compound (VOC) emissions. The project would also further our understanding of the basic design principles for polymers used in biomedical applications.