Dental Composites from Photoresponsive Addition-Fragmentation Filler Particles

项目摘要。 拟议的研究涉及开发交联型有机填料颗粒和表面- 自由基加成-断裂链转移(AFT)功能化的改性无机填料 牙科修复体复合材料中用于降低应力的部分。尽管在以下方面取得了重大进展 功能化无机填料的设计和在树脂(可聚合)相中添加AFT单体， 在牙科修复剂中，聚合过程中的应力发展仍然是一个重要的问题，它可能导致 复合材料的微裂纹，牙齿剥离，甚至牙齿断裂。功能模块的设计， 基于AFT的颗粒的交联化和随后在传统牙科树脂中的应用将实现共价 填料颗粒内的键重新排列，以在其发展时松弛应力。同样，AFT的成立也是如此 无机填料表面的部分是将动态化学引入填料的另一种方法 同时保持树脂的机械性能不变。 本研究的目的是解决填料和填料/树脂界面上的应力集中问题 利用共价自适应网络(CANS)范例。这种方法取代了静态绑定， 通常存在于具有动态键的交联网络中，这些键在存在的情况下重新排列到较低的应力状态 合适的激活物种。在AFT的情况下，活化物种是自由基，这些自由基也是活性的 大多数牙科修复剂用二甲基丙烯酸酯树脂光聚合过程中的种类 复合材料。第一个目标是开发AFT颗粒，以减少聚合过程中的应力发展 以及在经典玻璃系统的外部加载时，然后直接将这些颗粒作为添加剂实现 标准牙科树脂配方，并研究它们对应力行为的影响。接下来，我们将开发AFT 有机/无机纳米复合粒子与功能化二氧化硅纳米粒子，以绕过限制 如树脂粘度和复合材料的模数。第二个目标是使二氧化硅纳米颗粒功能化。 具有AFT部分，以便仅在填料/基质界面处实现键交换，而不保持 最终复合材料的力学性能。然后我们将结合有机AFT颗粒和 研究两种颗粒在牙科复合体中可能的协同效应。 为了实现这些目标，有目的的培训计划将使受训人员能够与导师和 学习他们在牙科材料方面的技术和实践经验。入选的指导委员会已经 在聚合物牙科材料的合成、表征和临床应用方面有丰富的经验， 以及行业考量。受训人员将接受相关和有意义的研究型培训 并进行深思熟虑和合乎道德的研究。

Project Summary. The proposed research involves the development of crosslinked organic filler particles and surface- modified inorganic fillers that are functionalized with radical addition-fragmentation chain transfer (AFT) moieties for stress reduction in dental restorative composites. Although there have been significant advances in the design of functionalized inorganic fillers and addition of AFT monomers to the resin (polymerizable) phase, stress development during polymerization is still a significant issue in dental restoratives that can lead microcracking of the composite, delamination from the tooth, or even tooth fracture. The design of functional, crosslinked AFT-based particles and subsequent implementation into classic dental resins will enable covalent bond rearrangement within the filler particle to relax stress as it develops. Similarly, incorporation of AFT moieties onto the surface of inorganic fillers is an additional method to introduce dynamic chemistry to the filler phase while maintaining the same mechanical properties of the resin. The purposed research will address stress concentration on the filler and filler/resin interface by taking advantage the Covalent Adaptable Networks (CANs) paradigm. This approach replaces the static bonds that normally exist in a crosslinked network with dynamic bonds that rearrange to a lower stress state in the presence of proper activating species. In the case of AFT, the activating species are free radicals, which are also the active species during the photopolymerization of the dimethacrylate based resins used in most dental restorative composites. The first aim is to develop AFT particles that reduce stress development both during polymerization and upon external loading of classic glassy systems, then implement these particles directly as an additive to standard dental resin formulations and study their effect on the stress behavior. Next, we will develop AFT organic/inorganic nanocomposite particles with functionalized silica nanoparticles to circumvent limitations such as resin viscosity and modulus of the composite. The second aim is to functionalize silica nanoparticles with AFT moieties to enable bond exchange only at the filler/matrix interface without maintaining the mechanical properties of the final composite. We will then incorporate the both the organic AFT particles and the functionalized to investigate possible synergistic effects of both particle types in a dental composite. To accomplish these goals, the purposed training plan will enable trainee to interact with mentors and learn from their technical and practical experience with dental materials. The selected mentoring committee has extensive experience with synthesis, characterization of polymeric dental materials, and clinical implementation, and industrial considerations. The trainee will receive relevant and meaningful training in research-oriented areas and conducting research both thoughtfully and ethically.