Heterogeneous Polymer Matrices from Nanogel Macromers

描述(申请人提供)：每年有数以亿计的牙科修复者使用美观的聚合物复合材料进行修复，现在这些治疗方法中占大多数。虽然受到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接。由于聚合物基质是收缩应力的来源，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的单体的方法。这项应用将证明，具有适当官能度的高分子、离散颗粒预聚体纳米凝胶可以作为尺寸稳定的大分子单体(或大分子单体)，与传统的二甲基丙烯酸酯单体高比例结合，显著降低最终聚合物形成时产生的应力，而不是收缩较大的小分子单体。为了实现这一目标，以下三个目标将指导该项目：(I)将审查纳米凝胶颗粒合成和结构控制的基础科学。纳米凝胶具有明确的尺寸(~10到500 nm)、可控的核/表面化学和可预测的机械/物理性能，并将被生产和表征。虽然初步数据表明，这些聚合物纳米粒子及其功能化大分子类似物很容易从常见单体中获得，但我们将扩展纳米凝胶的形态，以产生更复杂的核壳结构和梯度结构。(Ii)这些基于纳米凝胶的大分子单体代表了一系列颗粒尺寸、模数、官能度和结构复杂性，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异质性的共聚物。对于非填充和填充体系，将使用包括粘度、反应动力学、收缩/应力和机械强度/韧性在内的特性来确定与传统的二甲基丙烯酸酯树脂和复合材料相比能够产生重要性能优势的组合。同样，初步结果已经表明，与Bis-GMA/TEGDMA光聚合物对照相比，机械性能显著改善，聚合收缩和应力降低；然而，通过特定的纳米凝胶结构设计，有望进一步增强。(Iii)将详细探讨使用纳米大分子凝胶来模拟相分离的聚合物结构，以便更好地了解界面区域的产生和控制，以及利用聚合诱导相分离作为一种手段来获得具有极低收缩和应力的聚合物材料。该项目的预期结果是实际获得多种纳米凝胶结构，这些结构可以用作大分子，以显著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.