Heterogeneous Polymer Matrices from Nanogel Macromers

描述（由申请人提供）：每年使用美学聚合物复合材料进行数亿次牙科治疗，现在占这些治疗的大部分。虽然深受患者和从业者的欢迎，但牙科复合材料的临床性能和寿命并不理想。由于这些材料在聚合过程中产生的体积收缩和伴随的应力，不能可靠地实现与牙齿组织的无缺陷粘结。由于聚合物基体是收缩引起的应力的来源，也是限制复合材料的机械强度和韧性的组分，因此我们提出了所用单体的替代方法。代替以相当大的收缩率溶胀的小分子单体，本申请将证明具有适当官能度的被称为纳米凝胶的高分子量离散颗粒预聚物可以用作尺寸稳定的大分子单体（或大分子单体），其可以以高比例与常规二甲基丙烯酸酯单体组合以显著降低在形成最终聚合物时产生的应力。为了实现这一目标，以下三个目标将指导本项目：（i）纳米凝胶颗粒合成和结构控制的基础科学将被检查。将生产和表征具有良好定义的尺寸（~ 10至> 500 nm）、受控的核/表面化学和可预测的机械/物理性质的纳米凝胶。虽然初步的数据表明，这些聚合物纳米粒子和它们的功能化的大分子单体类似物是很容易从普通单体获得，我们将扩大纳米凝胶形态，以产生更复杂的核-壳和梯度结构。(ii)这些基于纳米凝胶的大分子单体，代表了一系列的粒度，模量，功能性和结构复杂性，然后将与传统的牙科单体组合，以产生具有由纳米凝胶引入的设计异质性的共聚物。对于未填充和填充系统，包括粘度、反应动力学、收缩/应力和机械强度/韧性在内的性能将用于确定与常规二甲基丙烯酸酯树脂和复合材料相比产生重要性能优势的组合。同样，初步结果已经证明，与Bis-GMA/TEGDMA光聚合物对照相比，机械性能显著改善，聚合收缩率和应力降低;然而，使用特定的纳米凝胶结构设计，预计会进一步增强。(iii)使用纳米凝胶大分子单体模型相分离的聚合物结构将详细探讨，以更好地了解创建和控制的界面区域，以及利用聚合诱导的相分离作为一种手段，以实现聚合物材料，表现出极低的收缩率和应力。该项目的预期成果是实际获得多种纳米凝胶结构，可用作大分子单体，以大幅改善牙科复合材料目前的缺陷。

DESCRIPTION (provided by applicant): Each year hundreds of millions of dental restorations are performed with esthetic polymeric composite materials now making up the majority of these treatments. While well received by patients and practitioners, the clinical performance and longevity of dental composites is not ideal. Because of the volumetric contraction and the accompanying stresses that develop during polymerization of these materials, defect-free bonding to tooth tissues can not be reliably attained. Since the polymer matrix is the source of the shrinkage-induced stress and also the component that limits the mechanical strength and toughness of composite materials, we propose an alternative approach to the monomers used. Instead of small molecule monomers that polymerize with considerable shrinkage, this application will demonstrate that high molecular weight, discrete particulate prepolymers known as nanogels, with appropriate functionality, can serve as dimensionally stable macromolecular monomers (or macromers) that can be combined in high proportions with conventional dimethacrylate monomers to dramatically decrease the stress that develops upon formation of the final polymer. To accomplish this, the following three aims will guide this project: (i) The basic science of nanogel particle synthesis and structural control will be examined. Nanogels with well defined size (~ 10 to > 500 nm), controlled core/surface chemistries and predictable mechanical/physical properties will be produced and characterized. While preliminary data has shown these polymeric nanoparticles and their functionalized macromer analogs are readily obtainable from common monomers, we will extend the nanogel morphology to produce more complex core-shell and gradient structures. (ii) These nanogel-based macromers, representing a range of particle size, modulus, degree of functionality and structural complexity, will then be combined with conventional dental monomers to produce copolymers with designed heterogeneity introduced by the nanogel. For both unfilled and filled systems, properties including viscosity, reaction kinetics, shrinkage/stress and mechanical strength/toughness will be used to identify combinations that produce important performance advantages compared with conventional dimethacrylate resins and composites. Again, preliminary results have already demonstrated significant improvements in mechanical properties as well as reduced polymerization shrinkage and stress compared with a Bis-GMA/TEGDMA photopolymer control; however, with specific nanogel structural designs, further enhancements are expected. (iii) The use of nanogel macromers to model phase separated polymer structures will be explored in detail to better understand the creation and control of the interfacial regions as well as to exploit polymerization-induced phase separation as a means to achieve polymeric materials that exhibit extremely low shrinkage and stress. The expected outcome of this project is practical access to a diverse array of nanogel structures that can be used as macromers to substantially improve current deficiencies in dental composite materials.