Hydrophobic bonding in alternating copolymers of maleic acid and alkyl vinyl ethers
Hydrophobic bonding in alternating copolymers of maleic acid and alkyl vinyl ethers
复制标题
马来酸和烷基乙烯基醚交替共聚物中的疏水键
DOI：
10.1021/j100708a020
复制
发表时间：
1970
期刊：
影响因子：
--
通讯作者：
U. Strauss
中科院分区：
文献类型：
--
作者：
P. Dubin;U. Strauss
本文通过电位滴定法和粘度法研究了不同侧链长度的马来酸酐和烷基乙烯基醚的一系列水解共聚物的疏水键对大分子结构的影响。虽然具有乙基乙烯基醚的共聚物表现为正常的弱多酸，丁基和己基共聚物在低pH下以超螺旋状态存在，并且随着中和度a的增加而经历向扩展状态的构象转变。随着侧链长度的增加，发生转变的范围向更高的a值移动。从电位滴定数据可以得到零电荷时超螺旋向伸展构象转变的自由能AG。对于丁基和己基共聚物，AGtat 25的值分别为310和1110 cal/mol残基。温度-温度依赖性的G表明，这两个和AS增加从负值到正值随着温度的升高，以前观察到的行为涉及其他系统的疏水键。从己基和丁基共聚物的AG差异，我们估计一个亚甲基对超螺旋形式的疏水稳定性的贡献为400卡/摩尔。
The effects of hydrophobic bonding on macromolecular structure were investigated by potentiometric titration and viscosity studies on a series of hydrolyzed copolymersof maleic anhydride and alkylvinyl ethers of varying side-chain length. While the copolymer with ethyl vinyl ether behaves as a normal weak polyacid, the butyl and hexyl copolymers exist in hypercoiled states at low pH and undergo conformational transitions to extended states as the degree of neutralization, a, is increased. The range over which the transition occurs is shifted to higher values of a with increasing side-chain length. The free energy of thetransition from hypercoil to extended conformation at zero charge, AG, may be obtained from the potentiometric titration data. Values of AGtat 25 are 310 and 1110 cal/mol residue for the butyl and hexyl copolymers, respectively. The tem-perature dependence of Gindicates that both and AS increase from negative to positive values with increasing temperature, a behavior previously observed for other systems involving hydrophobic bonding. From the difference in AGfor the hexyl and butyl copolymers we estimate the contribution of one methylene group to the hydrophobic stabilization of the hypercoiled form to be400 cal/mol.