Unique Polymeric Materials by Novel Processes

该提案包括三个研究重点，每个重点都是通过新的策略创造独特的聚合物材料，这些材料可能用于医疗和高科技应用。第一个重点是“智能”（刺激响应）两亲网络和膜，它们根据周围介质迅速改变其微形态。本研究的目的是合成、表征和评价概念上新的三组分三连续两亲膜，这些膜具有改善的氧、渗透性、机械性能和精确设计的孔隙尺寸。当前的目标将是制备用于治疗糖尿病的β细胞的免疫分离胶囊。胶囊的壁将是新型膜，其中包含用于水和水溶液运输的连续亲水聚乙二醇（PEG）相，用于O2运输的连续亲氧聚二甲基硅氧烷（PDMS）相，以及提供PEG和PDMS部分交联和增强的连续聚五甲基环硅氧烷（PD5）相。已知聚硅氧烷具有高氧渗透性，因此将产生O2跨膜运输的通道；因此，O2将通过水膨胀的PEG相和亲氧（氧特异性）PDMS/PD5通道通过水介导的运输扩散穿过膜壁。这些新型两亲膜的合成是基于最近发现的共氢化/水解/缩聚过程：乙烯基远旋聚乙二醇和-PDMS部分将被五甲基环硅氧烷（D5H）共氢化，D5H的残余SiH功能将被水解成SiOH基团，后者将交联得到新的膜。将使用分子量明确的PEG和PDMS预聚物，这将导致良好控制的结构。对第一代双组分膜的早期研究将为制备改进的生物相容性膜提供指导，这些膜将与生物学家和医学科学家共同进行评估。这些独特的膜将被设计成与生物人工胰腺共同评估的组件，以纠正糖尿病。第二个推力是建立在最近的发现，D5H可以很容易地在氢硅化（Karstedt的）催化剂和水的存在下聚合到PD5， PD5是一种具有前所未有的性能组合的新材料，即最低的Tg（~150℃），高热阻等。将研究D5H- PD5聚合的机理（水的作用、化学计量学等），并努力确定合成具有特定尺寸、体积和形态的PD5簇的条件。进一步的目标是通过新的工艺，并通过使用廉价的线性和环状聚硅氧烷的组合，创造出独特的弹性网络，表现出出色的热稳定性和氧化稳定性。这些网络将通过使用HO-PDMS-OH和PD5合成，并将基于PD5含有少量但足够数量的SiH基团的发现，这些SiH基团将与ho -远旋PDMS结合，形成耐热弹性网络。事实上，初步实验表明，所提出的合成是可行的。第三个推力的目的是合成，表征和测试新的全脂肪族热塑性弹性体（TPEs）。这些tpe将是软PIB内段与高Tg（~300℃）聚降冰片二烯外段结合的三星块和星块。要达到这一目的，首先要用阳离子活性聚合法制备带有叔氯末端的PIB块体或星形体，并利用这些基团与TiCl4结合，诱导降冰片二烯的聚合。这些新聚合物材料的特性和测试是推力的组成部分。所有必要的仪器、主要设备和专家建议都可以完成任务。这些研究对于产生具有潜在电子应用价值的新的脂肪族tpe家族具有重要意义。设想的活动将大大促进发现和理解，同时促进年轻专业人员（研究生和博士后）的教学和培训。与阿克伦大学、邻近大学和医院（在阿克伦和克利夫兰）以及德国和匈牙利的研究机构的研究人员的各种合作已经到位，并将继续下去。和以前一样，学生将参加地方、国家和国际会议和讲习班。对本科生和研究生的特殊指导已经开始并将继续下去。设想的研究本质上是多学科的，并将导致广泛参与跨学科的专题讨论会和会议。这项研究的结果将发表在最高质量的专业期刊上，并在会议上提出。

This proposal consists of three research thrusts, each focusing on the creation by novel strategies of unique polymeric materials of potential use for medical and high technology applications. The first thrust concerns "smart" (stimuli-responsive) amphiphilic networks and membranes that rapidly change their micromorphology depending on the surrounding medium. The aim of this thrust is to synthesize, characterize and evaluate conceptually new tricomponent tricontinuous amphiphilic membranes with improved O2, permeability, mechanical properties, and precisely designed pore dimensions. The immediate objective will be to prepare immunosiolatory capsules for beta cells for the treatment of diabetes. The walls of the capsules will be novel membranes that contain a continuous hydrophilic poly (ethylene glycol) (PEG) phase for the transport of water and aqueous solutions, a continuous oxyphilic polydimethylsiloxane (PDMS) phase for O2 transport, and a continuous polypentamethylcyclosiloxane (PD5) phase that provides crosslinking of the PEG and PDMS moieties, and reinforcement. Polysiloxanes are known to possess high O2 permeability, and thus will yield channels for O2 transport across the membrane; Thus O2 will diffuse through membrane walls via water-mediated transport by water-swollen PEG phases and by oxyphilic (oxygen-specific) PDMS/PD5 channels. The synthesis of these novel amphiphilic membranes is based on a recently discovered cohydrosilation/hydrolysis/polycondensation process: Thus, vinyl-telechelic PEG and -PDMS moieties will be cohydrosilated by pentamethylcyclosiloxane (D5H), the residual SiH functions of D5H will be hydrolyzed to SiOH groups, and the latter will crosslink to give novel membranes. Well-defined molecular weight PEG and PDMS prepolymers will be used which will result in well-controlled structures. Earlier research with first generation bicomponent membranes will provide guidance toward the preparation of improved biocompatible membranes that will be jointly evaluated with biologists and medical scientists. These unique membranes will be designed to become components that will be jointly evaluated with a bioartificial pancreas to correct diabetes. The second thrust is built upon the recent discovery that D5H can be readily polymerized in the presence of a hydrosilation (Karstedt's) catalyst and water to PD5, a new material with a combination of unprecedented properties, i.e., the lowest Tg on record (~150 degree C), high thermal resistance, etc. The mechanism of the D5H- PD5 polymerization will be studied (role of water, stoichiometry, etc.), and efforts will be made to define conditions for the synthesis of PD5 clusters of defined sizes, volumes and morphology. A further objective is to create by new processes, and by the use of a combination of inexpensive linear- and cyclic polysiloxanes, unique elastic networks that exhibit outstanding heat and oxidative stability. These networks will be synthesized by the use of HO-PDMS-OH and PD5, and will be based on the discovery that PD5 contains a small but sufficient number of SiH groups that will combine with the HO-telechelic PDMS to give thermally resistant elastic networks. Indeed, preliminary experiments have indicated that the proposed synthesis is feasible. The aim of the third thrust is the synthesis, characterization and testing of novel fully aliphatic thermoplastic elastomers (TPEs). These TPEs will be tri-and star-blocks of soft PIB inner segments bonded to high Tg (~300degrees C) polynorbornadiene outer segments. The objective will be reached by first preparing by living cationic polymerization PIB blocks or stars fitted with tert-chlorine termini, and using these groups, in conjuction with TiCl4, to induce the polymerization of norbornadiene. The characteriztion and testing of these new polymeric materials are integral parts of the thrusts. All the necessary instrumentation, major equipment, and expert advise are available to complete the tasks. These studies will be of significance for the generation of a new family of aliphatic TPEs with potential electronic applications.The envisioned activities will significantly advance discovery and understanding, while fostering teaching and training of young professionals (graduate students and postdoctorals). Various collaborations with researchers at The University of Akron, neighboring universities and hospitals (both in Akron and in Cleveland), and research institutes in Germany and Hungary are in place and will be continued. Students will, as before, participate at local, national, and international meetings and workshops. Special mentoring of undergraduates and graduate students has started and will continue. The envisioned research in inherently multidisciplinary and will lead to extensive participation in interdisciplinary symposia and conferences. Results of this research will be published in highest quality professional journals and presented at meetings.