用^1H NMR研究正丁醇对PEO-PPO-PEO嵌段共聚物胶团形成的影响

1-Butanol Affects Micellization of PEO-PPO-PEO Triblock Copolymer in Aqueous Solution

采用1H NMR波谱技术研究了正丁醇对PEO-PPO-PEO嵌段共聚物温度依赖的胶团化过程影响.实验结果表明,正丁醇的加入急剧地降低嵌段共聚物的临界胶团温度(CMT).化学位移变化表明正丁醇烷基端与嵌段共聚物PPO链段之间的疏水相互作用是导致嵌段共聚物CMT降低的主要原因.选择性激发ROE实验进一步证实,在形成的嵌段共聚物-正丁醇混合胶团中,正丁醇的烷基链段进入胶团内核而正丁醇的羟基端则处于胶团外壳一侧.

The effects of 1-butanol on temperature-dependent micellization of poly（ethylene oxide）- poly（propylene oxide）-poly（ethylene oxide） （PEO PPO PEO） triblock copolymer （PEO-PPO-PEO） in D20 were investigated by 1H nuclear magnetic resonance （NMR） spectroscopy. The chemical shift of the methyl groups in the PPO blocks was used to characterize the aggregation process. It was found that addition of 1-butanol reduced the critical micellization temperature （CMT） of PEO-PPO-PEO in aqueous solu tion. The chemical shift of the methyl protons in 1-butanol was found to increase after mixing with PEO-PPO-PEO, indicating that the alkyl head of 1 butanol must have interacted with the triblock copolymer and entered into the micellar core. The results of selective ROE experiments further demonstrated that, by such interaction, the alkyl head of 1-butanol was inserted into the hydrophobic micellar core while its hydroxyl tail remained at the micellar shell.