Dental Composite Resins with Polymer Nanofibers

描述(由申请人提供)：几十年来，改善机械性能和降低内应力(由聚合收缩引起)一直是聚合物牙科修复复合材料的主要研究成果之一。近年来迅速发展的“电纺”技术及其新产品“聚合物纳米纤维”为解决这些问题提供了潜在的解决方案。直径从几纳米到几百纳米的聚合物纳米纤维可以由各种聚合物溶液或熔体制成。在电纺过程中，“弯曲不稳定性”这一关键现象导致了高达100万S(-1)的极大延伸率。如此巨大的伸长流量可以很好地沿纳米纤维轴排列大分子链以及纳米薄膜(例如层状硅酸盐)；因此，电纺纳米纤维可以非常坚固。电纺聚合物纳米纤维通常作为无纺布收集，可以与牙科单体(例如，Bis-GMA/TEGDMA混合物)浸泡并嵌入其中。聚合后，复合树脂的形态类似于互穿网络(IPN)。本研究首次将电纺聚合物纳米纤维引入牙科材料的制备。特别是，将研究使用尼龙6和/或尼龙6/层状硅酸盐纳米复合材料(NLS)的强纳米纤维来提高强度，以及使用弹性纳米纤维的三元乙丙橡胶(EPDM)来降低内应力。其他目标包括：(1)研究静电纺丝工艺以制造具有理想形态和物理性能的纳米纤维，(2)通过对纳米纤维进行化学修饰和对纳米纤维进行等离子表面处理，改善纳米纤维填料和基质树脂之间的界面性能，(3)评估尼龙6、NLS和三元乙丙橡胶纳米纤维的混杂嵌入，以最大化强度和最小化内应力，以及(4)表征长期机械和物理性能，如磨损、水老化和热循环，以实现具有理想性能(如高强度和/或最小内应力)的最佳复合树脂。该项目将提供(1)电纺聚合物纳米纤维增强和降低牙科树脂内应力的机理；(2)纳米纤维增强和/或增韧牙科复合树脂的微结构设计和加工指南；以及(3)用于牙科修复(以及潜在的其他生物医学)应用的下一代高性能复合树脂的基础。

DESCRIPTION (provided by applicant): Improving mechanical properties and reducing internal stresses (induced by polymerization shrinkage) have been among the major research efforts for polymeric dental restorative composites for decades. The recently fast developing technology of "electrospinning" and its novel product "polymer nanofibers", provide a potential solution to solve these problems. Polymer nanofibers, with diameters ranging from several nanometers to several hundred nanometers, can be made from a variety of polymer solutions or melts. In the process of electrospinning, the key phenomenon "bending instability" results in extremely large elongational flow rate of up to 1,000,000 s(-1). Such huge elongational flow rate can well align macromolecule chains as well as nanofillers (e.g., layered silicates) along the nanofiber axis; therefore, electrospun nanofibers can be extraordinary strong. The electrospun polymer nanofibers, typically collected as non-woven fabrics, can be soaked with and embedded into dental monomers (e.g., Bis-GMA/TEGDMA mixture). After polymerization, the composite resins are in the form similar to the interpenetration network (IPN). In this research, for the first time, the electrospun polymer nanofibers will be introduced to prepare dental materials. In particular, the use of strong nanofibers of Nylon 6 and/or Nylon 6/layered silicate nanocomposites (NLS) to improve the strength, and the use of elastomeric nanofibers of ethylene-propylene-diene elastomer (EPDM) to reduce the internal stresses, will be studied. Other objectives include (1) investigating the process of electrospinning to make nanofibers with desirable morphological and physical properties, (2) improving interfacial properties between the filler of nanofibers and the matrix resin, through both chemical modifications of the macromolecules and plasma surface treatment of the nanofibers, (3) evaluating hybrid embedding of Nylon 6, NLS and EPDM nanofibers to maximize strength, and to minimize internal stress, and (4) characterizing long-term mechanical and physical properties, such as wear, water aging and thermal cycling, for optimal composite resins with desirable properties (e.g. high strength and/or minimum internal stresses). This project will provide (1) the mechanisms of electrospun polymer nanofiber reinforcement and reduction of internal stress for dental resins; (2) guidelines on microstructural design and processing of nanofiber reinforced and/or toughened dental composite resins; and (3) a basis for the next generation of high performance composite resins for dental restorative (and potentially other biomedical) applications.