RUI: Utilization of a Thio-Bromo Substitution Reaction for the Preparation of a New Class of ROMP Hydrogels

水凝胶是不溶于水但在水存在下溶胀的聚合物网络。由于这种性质，它们在生物医学领域有着广泛的应用。德克萨斯农工大学金斯维尔分校的克里斯托弗·霍布斯教授的研究小组探索了制备功能性水凝胶的新途径。 特别是，他的研究小组开发了一种高效且不含贵金属的反应，用于水凝胶的合成和改性。 该项目为许多代表性不足的本科生提供跨学科的研究经验，为科学，技术，工程和数学（STEM）领域的职业生涯提供了重要的垫脚石。此外，霍布斯教授组织高分子化学研讨会，在其中高中教师学习的方法和实验，可用于介绍高分子化学方面在他们的科学课，希望招募一个新的，多样化的一代年轻学生干领域。这个项目的重点是利用一个简单的，硫醇和α-溴代酯之间的无催化剂取代反应，用于制备一类新的水凝胶。 该方法采用硫代溴取代反应将含α-溴酯的聚异戊二烯和聚（氧杂降冰片烯）转化为具有官能度的聚合物（例如，羟基、氨基和离子基团），其已知向大分子结构中注入水溶胀性。 所得聚合物与二硫醇的交联产生一类新的水凝胶。 虽然通过开环易位聚合（ROMP）制备含α-溴酯的聚异戊二烯和聚（氧杂降冰片烯）需要使用钌催化剂，但是这些聚合物向水凝胶的转化涉及使贵金属的使用最小化的无金属反应。 在NSF大分子，超分子和纳米化学计划的支持下，Hobbs教授的小组进行了研究，以检查这种合成方法的有效性以及水凝胶性能对聚合物主链，侧链基团和交联剂特性的依赖性。

Hydrogels are polymeric networks that are not soluble in water but instead swell in the presence of water. Because of this property, they have broad applications in the biomedical fields. Professor Christopher Hobbs' group at Texas A&M University-Kingsville explores new routes toward the preparation of functional hydrogels. Specially, his research group develops a highly efficient and precious metal-free reaction for the synthesis and modification of hydrogels. This project provides interdisciplinary research experience to many underrepresented undergraduate students, delivering a vital stepping stone toward careers in fields of science, technology, engineering, and mathematics (STEM). Additionally, Professor Hobbs organizes Polymer Chemistry Workshops, in which high school teachers learn methods and experiments that can be used to introduce aspects of polymer chemistry in their science classes in the hopes of recruiting a new, diverse generation of young students to STEM fields.This project focuses on the utilization of a facile, catalyst-free substitution reaction between thiols and alpha-bromo esters for the preparation of a new class of hydrogels. The process employs thio-bromo substitution reactions to convert alpha-bromoester-containing polynorbornenes and poly(oxanorbornene)s to polymers with functionality (e.g., hydroxyl, amino, and ionic groups) known to instill water-swellability to macromolecular architectures. Cross-linking of the resulting polymers with dithiols produces a new class of hydrogels. While the preparation of alpha-bromoester-containing polynorbornenes and poly(oxanorbornene)s by Ring Opening Metathesis Polymerization (ROMP) requires the use of a ruthenium catalyst, the conversion of these polymers to hydrogels involves metal-free reactions that minimize the use of precious metals. With the support from the NSF Macromolecular, Supramolecular and Nanochemistry Program, Professor Hobbs' group conducts research to examine the effectiveness of this synthetic approach and the dependence of the hydrogel properties on the polymeric backbone, side chain groups, and cross-linker identity.