Heterogeneous Polymer Matrices from Nanogel Macromers

描述（由申请人提供）：每年有数以亿计的牙齿修复使用美观的聚合物复合材料进行，现在占这些治疗的大多数。虽然牙科复合材料的临床性能和使用寿命并不理想，但深受患者和医生的欢迎。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，无法可靠地实现与牙齿组织的无缺陷粘合。由于聚合物基体是收缩应力的来源，也是限制复合材料机械强度和韧性的成分，我们提出了一种替代使用单体的方法。该应用将证明，具有适当功能的高分子量、离散颗粒预聚体（即纳米凝胶）可以作为尺寸稳定的大分子单体（或大分子），与传统的二甲丙烯酸酯单体以高比例结合，以显着降低最终聚合物形成时产生的应力，而不是具有相当收缩的小分子单体。为了实现这一目标，以下三个目标将指导这个项目：(i)纳米凝胶粒子合成和结构控制的基础科学将被检查。纳米凝胶具有明确的尺寸（~ 10 ~ 500nm）、可控制的岩心/表面化学性质和可预测的机械/物理性质。虽然初步数据表明这些聚合物纳米颗粒及其功能化的大分子类似物很容易从普通单体中获得，但我们将扩展纳米凝胶的形态，以产生更复杂的核壳和梯度结构。（ii）这些基于纳米凝胶的高分子聚合物，代表了一系列的粒径、模量、功能程度和结构复杂性，然后将与传统的牙科单体结合，产生具有纳米凝胶引入的设计非均质性的共聚物。对于未填充和填充的体系，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传统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，与Bis-GMA/TEGDMA光聚合物对照相比，初步结果已经证明了机械性能的显著改善，以及聚合收缩和应力的降低；然而，随着特定的纳米凝胶结构设计，期望进一步增强。（iii）使用纳米凝胶大分子来模拟相分离的聚合物结构将被详细探索，以更好地理解界面区域的产生和控制，以及利用聚合诱导的相分离作为一种手段来实现聚合物材料表现出极低的收缩和应力。该项目的预期结果是实际获得各种各样的纳米凝胶结构，这些纳米凝胶结构可以用作大分子，从而大大改善目前牙科复合材料的不足。

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.