IMPROVED PREVENTIVE/RESTORATIVE RESINS AND COMPOSITES

描述：仍有必要开发新的牙科单体，以克服限制树脂基牙科修复体使用寿命的缺点。目前牙科树脂基复合材料存在耐磨性不足、边缘渗漏导致继发性龋齿、填料-树脂界面水解性破坏等临床性能缺陷。在这里，建议将可聚合单体的化学核心结构与所得到的牙科材料中的选定性质相关联。例如，含有刚性芳香族和柔性脂肪族基团的二甲基丙烯酸酯单体将导致聚合物具有更高的韧性，这是改善牙科复合材料耐磨性的理想特性。在这一探索性的应用中，我们建议合成具有不同数量的刚性芳香族基团和柔性醚键的芳香酸单体。然后，我们将研究这些化学结构对所得聚合物的机械和物理性能的影响(目标1)。如有必要，将使用TLC、LC-MS、FTIR、核磁共振等分析方法。将测定聚合物的断裂韧性、转化率、吸水率、粘弹性和玻璃化转变温度。将对单体进行计算机模拟，以建立醚键转动能与合成单体所得聚合物韧性之间的经验关联(目标2)。由于空间位阻和电子相互作用，芳香族基团的数量和体积等分子特征可以增加分子的转动能。这项研究还将包括计算将醚键改变为例如全氟-异丙基、羰基或砜(-SO2-)基团所产生的能量等。这种模型可以表明单体的哪些分子内特征对于控制聚合物的韧性是重要的。在这些实验中收集的数据将用于支持更大的R01赠款申请，其长期目标是开发用于粘合剂和粘合复合材料的更好的耐用材料。

DESCRIPTION: There is still a need to develop new Dental monomers to overcome the shortcomings that limit the useable lifetime of resin based Dental restorations. Current day resin-based Dental composites have clinical performance deficiencies that include inadequate resistance to wear, secondary caries as a result of marginal leakage, and hydrolytic breakdown of filler-resin interface. Here it is proposed to correlate the chemical core structure of a polymerizable monomer to selected properties in the resulting Dental material. For example, dimethacrylate monomers with rigid aromatic and flexible aliphatic groups will result in polymers with increased toughness, a desired property for improving wear resistance in Dental composites. In this exploratory application we propose to synthesize aromatic acid monomers with varying numbers of rigid aromatic groups and flexible ether linkages interspaced between them. We will then study the influence of these chemical structures on the mechanical and physical properties of the resulting polymers (Aim 1). Analytical methods such as TLC, LC-MS, FTIR, NMR, and others will be used as necessary. Fracture toughness, conversion, water sorption and the viscoelastic properties and glass transition temperature of the polymers will be determined. Computer modeling of the monomers will be carried out to build an empirical correlation between the energy of rotation about the ether linkage and the resulting toughness of the polymer from the synthesized monomers (Aim 2). Molecular features such as the number and bulkiness of the aromatic groups can increase the energy of rotation due to steric hindrances and electronic interactions. The study will also include calculating the resulting energies from changing the ether linkage to e.g., a perfluoro-isopropylidene, carbonyl, or sulfone (-SO2-) group and others. This modeling may indicate which intramolecular features of the monomer are important for controlling the toughness of the polymer. The data gathered in these experiments will serve to support a larger R01 grant application with the long-term objectives of developing improved durable materials for adhesives and adhesive composites.