Karikari Afia S, Edwards Wesleigh F, Mecham Jeffrey B, Long Timothy E
Department of Chemistry, Macromolecules and Interfaces Institute, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
Biomacromolecules. 2005 Sep-Oct;6(5):2866-74. doi: 10.1021/bm050375i.
Four-arm, star-shaped poly(D,L-lactide) (PDLLA) oligomers of controlled molar mass and narrow molar mass distribution were successfully synthesized by use of an ethoxylated pentaerythritol initiator. Derivatization of the terminal hydroxyl groups with either methacrylic anhydride (MAAH) or 2-isocyanatoethyl methacrylate (IEM) to yield PDLLA-M (M = methacrylate end group) and PDLLA-UM (UM = urethane methacrylate end group), respectively, was monitored by in situ Fourier transform infrared (FTIR) spectroscopy. Photo-cross-linking of the functional oligomers yielded networks with high gel contents (>95%). The glass transition temperature (T(g)) of these networks was strongly dependent on prepolymer molar mass, and networks based on low molar mass precursors were more rigid than the networks obtained from higher molar mass oligomers. The tensile strength (TS) and Young's modulus of the PDLLA-M samples, approximately 7 and 17 MPa, respectively, were significantly lower than the values of 19 MPa (TS) and 113-354 MPa (Young's modulus) for the PDLLA-UM samples. The introduction of terminal hydrogen-bonding sites that were adjacent to the photo-cross-linking site resulted in higher performance poly(lactide)-based bioadhesives.
通过使用乙氧基化季戊四醇引发剂，成功合成了具有可控摩尔质量和窄摩尔质量分布的四臂星形聚（D，L-丙交酯）（PDLLA）低聚物。分别用甲基丙烯酸酐（MAAH）或甲基丙烯酸2-异氰酸乙酯（IEM）对末端羟基进行衍生化，以生成PDLLA-M（M = 甲基丙烯酸酯端基）和PDLLA-UM（UM = 聚氨酯甲基丙烯酸酯端基），通过原位傅里叶变换红外（FTIR）光谱进行监测。功能性低聚物的光交联产生了具有高凝胶含量（>95%）的网络。这些网络的玻璃化转变温度（T(g)）强烈依赖于预聚物摩尔质量，基于低摩尔质量前体的网络比由高摩尔质量低聚物获得的网络更硬。PDLLA-M样品的拉伸强度（TS）和杨氏模量分别约为7和17 MPa，明显低于PDLLA-UM样品的19 MPa（TS）和113 - 354 MPa（杨氏模量）值。在光交联位点附近引入末端氢键位点导致了性能更高的聚丙交酯基生物粘合剂。
