A graphical method for the determination of the mode of hydrolysis of biodegradable polymers
A graphical method for the determination of the mode of hydrolysis of biodegradable polymers
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DOI：
10.1023/a:1016276830464
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发表时间：
1995-12-01
影响因子：
3.7
通讯作者：
Shih, C
中科院分区：
文献类型：
--
作者：
Shih, C
目的.建立一种定性测定生物降解聚合物水解过程中断裂方式的方法。方法.该方法需要通过（1）HNMR或HPLC测定单体的摩尔分数（m（1）），并通过（1）HNMR测定聚合物降解程度（α）。如果主链键的断裂是完全随机的，则单体的摩尔分数必须等于Kuhn（1）预测的降解程度的平方。如果退化遵循排他的排水端“解压缩"机制，则m（1）= alpha。落在理论曲线（m（1）对α）上的实验数据证实了相应的断裂模式。如果数据落在两条曲线之间，则表明链端断裂比随机断裂更快。当数据低于这两条曲线时，表明链端键的反应性低于内部键。聚原酸酯的酸催化水解和聚乳酸的碱催化水解都是通过无规断裂机理进行的，而聚乳酸的酸催化水解表现出更快的链端断裂。
Purpose. To develop a qualitative method for the determination of the mode of scission in the hydrolysis of biodegradable polymers. Methods. The method requires determination of the molar fraction of monomer (m(1)) by (1)HNMR or HPLC, and the degree of polymer degradation (alpha) determined by (1)HNMR.Results. If the scission of the backbone bonds is completely random, the molar fraction of the monomer must equal the square of the degree of degradation as predicted by Kuhn (1). If the degradation follows an exclusive drain-end ''unzipping'' mechanism then, m(1) = alpha. Experimental data falling on the theoretical curves (m(1) vs. alpha) confirm the corresponding mode of scission. If the data fall between the two curves, it suggests a faster chain-end scission than random scission. When data fall below both of these curves, it suggests the chain-end bonds are less reactive than the internal bonds.Conclusions. The acid catalyzed hydrolysis of a poly(ortho ester) and the base catalyzed hydrolysis of poly(D,L-lactide) (PLA) were by a random scission mechanism, while acid catalyzed hydrolysis of PLA demonstrated faster chain-end scission.