Department of Chemistry and Biochemistry, Long Island University, One University Plaza, Brooklyn, NY 11201, United States.
Department of Chemistry and Biochemistry, Long Island University, One University Plaza, Brooklyn, NY 11201, United States.
Int J Biol Macromol. 2017 Sep;102:1130-1137. doi: 10.1016/j.ijbiomac.2017.04.095. Epub 2017 Apr 27.
Poly(3-hydroxybutyrate) (PHB) is a microbially synthesized polymer, which is often purified by alkaline treatment. The effect of microstructure on alkaline hydrolysis has been studied by varying concentration of base and the temperature. The morphologies of PHB films before and after degradation were evaluated using DSC and FTIR spectroscopy. The hydrolytic degradation study by weight loss measurement revealed that the crystallinity of PHB greatly decreased the hydrolytic ability of PHB. The crystallization of PHB and the effect of base on hydrolysis was investigated by time dependent FTIR spectroscopy. The normalized absorbance of 3010cm and 1183cm were used to characterize the crystalline and the amorphous phases of PHB. FTIR spectroscopy reveal that the extent of hydrolysis decreased with increasing crystallinity. The crotonic acid was detected as a major product after hydrolysis, confirmed by UV/Visible and proton NMR spectroscopy. The normalized absorbance of the crystalline band at 3010cm band remained constant, suggesting that there is no significant change in crystallinity with degradation. The normalized amorphous band at 1183cm showed a decrease in absorbance ratio, suggesting degradation of the amorphous phase. Our data suggests that alkaline hydrolysis depends on concentration of base and the crystallinity of PHB.
聚(3-羟基丁酸酯) (PHB) 是一种微生物合成的聚合物，通常通过碱性处理进行纯化。通过改变碱的浓度和温度来研究微观结构对碱性水解的影响。使用 DSC 和 FTIR 光谱法评估 PHB 薄膜在降解前后的形态。通过重量损失测量进行的水解降解研究表明，PHB 的结晶度大大降低了 PHB 的水解能力。通过时间相关的 FTIR 光谱研究了 PHB 的结晶和碱对水解的影响。归一化吸收 3010cm 和 1183cm 用于表征 PHB 的结晶相和非晶相。FTIR 光谱表明，水解程度随结晶度的增加而降低。水解后检测到主要产物为巴豆酸，这通过 UV/可见和质子 NMR 光谱得到证实。结晶带在 3010cm 处的归一化吸收带保持不变，表明结晶度在降解过程中没有明显变化。1183cm 处的归一化非晶带的吸收比值下降，表明非晶相的降解。我们的数据表明，碱性水解取决于碱的浓度和 PHB 的结晶度。
