George Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 771 Ferst Drive, Atlanta, GA 30332, USA.
Acta Biomater. 2011 Feb;7(2):558-67. doi: 10.1016/j.actbio.2010.09.001. Epub 2010 Sep 7.
Photopolymerizable (meth)acrylate networks are potentially advantageous biomaterials due to their ability to be formed in situ, their fast synthesis rates and their tailorable material properties. The objective of this study was to evaluate how immersion time in phosphate-buffered saline (PBS) affects the toughness of photopolymerizable methyl acrylate (MA)-co-methyl methacrylate-co-poly(ethylene glycol) dimethacrylate networks containing various concentrations of MA. Stress-strain behavior was determined by performing tensile strain to failure testing after soaking in PBS for different periods (1 day up to 9 months). In tandem, differential scanning calorimetry and PBS content measurements were undertaken at each time point in order to determine whether time-dependent changes in toughness were related to changes in T(g) or PBS absorption. The effect of immersion time on network toughness was shown to be dependent upon composition in a manner related to the viscoelastic state of the polymer upon initial immersion in PBS. The results demonstrate that tough acrylate-based materials may not maintain their toughness after several months in PBS. In addition, decreasing the PBS content by changing the network hydrophobicity resulted in better toughness maintenance after 9 months. The results provide a possible means to toughen various amorphous acrylate-based implant materials that are being explored for load-bearing biomedical applications, beyond the systems considered in this work.
光聚合（甲基）丙烯酸酯网络是一种有潜在优势的生物材料，因为它们能够原位形成，具有较快的合成速率和可定制的材料性能。本研究的目的是评估在磷酸盐缓冲盐水（PBS）中浸泡时间如何影响含有不同浓度甲基丙烯酸甲酯（MA）的光聚合甲基丙烯酸甲酯（MA）-共甲基丙烯酸甲酯-co-聚（乙二醇）二甲基丙烯酸酯网络的韧性。通过在 PBS 中浸泡不同时间（1 天至 9 个月）后进行拉伸应变至失效测试来确定应力-应变行为。同时，在每个时间点进行差示扫描量热法和 PBS 含量测量，以确定韧性的时间依赖性变化是否与 Tg 或 PBS 吸收的变化有关。结果表明，网络韧性随组成的变化而变化，这与聚合物在初始浸入 PBS 时的粘弹性状态有关。结果表明，在 PBS 中浸泡几个月后，韧性好的丙烯酸盐基材料可能无法保持其韧性。此外，通过改变网络疏水性降低 PBS 含量，可在 9 个月后更好地保持韧性。该结果为增韧各种正在探索用于承重生物医学应用的无定形丙烯酸盐基植入材料提供了一种可能的方法，超出了本工作中考虑的系统。
