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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Improved micellar hydration and gelation characteristics of PEO-PPO-PEO triblock copolymer solutions in the presence of LiCl
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Improved micellar hydration and gelation characteristics of PEO-PPO-PEO triblock copolymer solutions in the presence of LiCl

机译：LiCl存在下改善PEO-PPO-PEO三嵌段共聚物溶液的胶束水化和凝胶化特性

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摘要

LiCl-induced changes in the micellar hydration and gelation characteristics of aqueous solutions of the two triblock copolymers F127 (EO100PO70EO100) and P123 (EO20PO70EO20) (where EO represents the ethylene oxide block and PO represents the propylene oxide block) have been studied by small-angle neutron scattering (SANS) and viscometry. The effect of LiCl was found to be significantly different from those observed for other alkali metal chloride salts such as NaCl and KCl. This can be explained on the basis of the complexation of hydrated Li+ ions with the PEO chains in the micellar corona region. The interaction between the chains and the ions is more significant in the case F127 because of its larger PEO block size, and therefore, micelles of this copolymer show an enhanced degree of hydration in the presence of LiCl. The presence of the hydrated Li+ ions in the micellar corona increases the amount of mechanically trapped water there and compensates more than the water molecules lost through the dehydration of the PEO chains in the presence of the Cl- ions. The enhancement in micellar hydration leads to a decrease in the minimum concentration required for the F127 solution to form a room-temperature cubic gel phase from 18% to 14%. Moreover, for both copolymers, the temperature range of stability of the cubic gel phase also increases with increasing LiCl concentration, presumably because of the ability of the Li+ ions to reduce micellar dehydration with increasing temperature. Viscosity studies on a poly(ethylene glycol) (PEG) homopolymer with a size equivalent to that of the PEO block in F127 (4000 g/mol) also suggest that the dehydrating effect of the Cl- ion on the PEG chain is compensated by its interaction with the hydrated Li+ ions.
机译：研究了LiCl诱导的两种三嵌段共聚物F127（EO100PO70EO100）和P123（EO20PO70EO20）（其中EO代表环氧乙烷嵌段而PO代表环氧丙烷嵌段）水溶液的胶束水合和胶凝特性变化。角中子散射（SANS）和粘度测定法。发现LiCl的作用与其他碱金属氯化物盐（如NaCl和KCl）观察到的作用明显不同。这可以根据胶束电晕区域中水合的Li +离子与PEO链的络合来解释。在F127情况下，由于其较大的PEO嵌段尺寸，链与离子之间的相互作用更为显着，因此，该共聚物的胶束在LiCl存在下显示出增强的水合度。胶束电晕中水合Li +离子的存在增加了在那里机械捕获的水的量，并补偿了在Cl-离子存在下由于PEO链脱水而损失的水分子所造成的损失。胶束水合作用的增强导致F127溶液形成室温立方凝胶相所需的最低浓度从18％降低到14％。而且，对于两种共聚物，立方凝胶相的稳定性的温度范围也随着LiCl浓度的增加而增加，这可能是因为Li +离子具有随温度升高而减少胶束脱水的能力。对尺寸相当于F127中的PEO嵌段（4000 g / mol）的聚（乙二醇）（PEG）均聚物的粘度研究还表明，Cl-离子对PEG链的脱水作用可以通过其对C与水合锂离子的相互作用。

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