Objective

The objective of this study was to demonstrate an approach with potential to increase the life of dental restorative polymers in water, by maintaining their strength and toughness with varied content of inert or reactive styrenic pre-polymeric additives. It was hypothesized that addition of styrene-co-divinylbenzene nanogels to a conventional dimethacrylate resin (e.g. TEGDMA) would reduce its susceptibility towards hydrolytic degradation, while maintaining equivalent mechanical properties.

Methods

Polymerization kinetics and functional group conversions were determined by Fourier transform infrared spectroscopy. Triple-detection gel permeation chromatography was used for nanogel particle characterization. A goniometer was used to measure water contact angle on experimental and control photocured polymers. Hydrolytic degradation and mass loss evaluation was performed after extended water storage of an intentionally hydrolytically degradable polymer. Resin viscosity was determined rheometrically and polymer mechanical properties were evaluated using three-point flexural testing with TEGDMA-nanogel formulations.

Results

The polymer network with highest level of nanogel loading (50 wt%) and the highest level of internal nanogel crosslinking (50 mol%) had the lowest degree of equilibrium swelling ratio and mass loss. The flexural modulus and ultimate strength of polymerized TEGDMA and styrenic nanogel-modified TEGDMA were not statistically different (p > 0.05).

Significance

Due to improved shielding throughout the bulk of methacrylate-based polymers, including an example with an intentionally hydrolytically labile network structure, and a dramatic decrease of water uptake while maintaining equivalent mechanical properties, styrenic nanogel additives especially in high loading levels provide an excellent alternative to eliminate the adverse effects of water and presumably salivary fluids.

中文翻译：

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通过集成的苯乙烯纳米凝胶抑制不稳定聚合物网络中的水解降解

客观的

本研究的目的是展示一种方法，通过使用不同含量的惰性或反应性苯乙烯预聚物添加剂来保持其强度和韧性，从而延长牙科修复聚合物在水中的使用寿命。据推测，将苯乙烯-二乙烯基苯纳米凝胶添加到传统的二甲基丙烯酸酯树脂（例如 TEGDMA）中会降低其对水解降解的敏感性，同时保持等效的机械性能。

方法

聚合动力学和官能团转化率由傅里叶变换红外光谱法确定。三重检测凝胶渗透色谱用于纳米凝胶颗粒表征。测角仪用于测量实验和对照光固化聚合物的水接触角。水解降解和质量损失评估是在有意水解可降解聚合物的长期储水后进行的。树脂粘度通过流变测定法确定，聚合物机械性能通过 TEGDMA-纳米凝胶配方的三点弯曲测试进行评估。

结果

具有最高纳米凝胶负载水平 (50 wt%) 和最高水平纳米凝胶内部交联 (50 mol%) 的聚合物网络具有最低程度的平衡溶胀比和质量损失。聚合的 TEGDMA 和苯乙烯纳米凝胶改性的 TEGDMA 的弯曲模量和极限强度没有统计学差异（p > 0.05）。

意义

由于整个基于甲基丙烯酸酯的聚合物的屏蔽性能得到改善，包括一个具有故意水解不稳定网络结构的例子，以及在保持等效机械性能的同时显着降低吸水率，苯乙烯纳米凝胶添加剂特别是在高负载水平下提供了一种极好的替代品消除水和可能是唾液的不利影响。