Phase separation in binary polymer solution: Gelatin/Poly(ethylene glycol) system
Phase separation in binary polymer solution: Gelatin/Poly(ethylene glycol) system
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DOI：
10.1016/j.molliq.2013.12.035
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发表时间：
2014-12
影响因子：
6
通讯作者：
M. Yanagisawa;Yutaro Yamashita;S. Mukai;M. Annaka;M. Tokita
中科院分区：
文献类型：
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作者：
M. Yanagisawa;Yutaro Yamashita;S. Mukai;M. Annaka;M. Tokita
系统地研究了明胶和聚乙二醇（PEG）水溶液的相行为。随着温度的降低，明胶/PEG溶液变得不透明并发生相分离。随着明胶浓度（Cg）的增加，体系的相分离点（Tp）增加。但当Cg低于临界值（C_2g）时，Tp随C_2g的降低而略有增加。此外，在C_（60）附近，相分离机制由亚稳分解型转变为成核生长型。PEG浓度（Cpeg）和PEG分子量（Mpeg）的增加使Tp曲线升高。温度的进一步降低导致明胶的溶胶-凝胶转变。在没有PEG的明胶溶液的情况下，明胶凝胶的熔融温度（Tm）随着Cg的增加而增加，并且接近饱和点。PEG的加入使Tm曲线更接近饱和点，这意味着具有较大Cg的样品的Tm在较低Cg时接近饱和点。此外，明胶凝胶的熔融焓随着CpegandMpeg的增加而增加。这些结果表明，PEG的加入增加了明胶链之间的氢键的强度。Tp曲线出现极小值可能是由于低Cg时链内聚集的自聚集和高Cg时链间缔合的相分离相互作用的结果。
We systematically investigated the phase behavior of gelatin and poly(ethylene glycol) (PEG) aqueous solution. With a decrease in temperature, the gelatin/PEG solution became opaque and underwent phase separation. The phase separation point (Tp) was increased with an increase in concentration of gelatin concentration (Cg). However, whenCgwas lower than a critical value (C⁎g),Tpwas slightly increased with decreasingCg. In addition, the phase separation mechanism was changed from spinodal decomposition type to nucleation growth type at aroundC⁎g. The increases in PEG concentration (Cpeg) and in the molecular weight of PEG (Mpeg) raised theTpcurve. A further decrease in temperature resulted in a sol–gel transition for gelatin. In the case of a gelatin solution without PEG, the melting temperature of the gelatin gel (Tm) increased with an increase inCgand approached a saturation point. The addition of PEG raised theTmcurve closer to the saturation point, implying thatTmfor the sample with a largerCpegreached the saturation point at a lowerCg. Furthermore, melting enthalpy for the gelatin gel was increased with increases inCpegandMpeg. These results indicate that the addition of PEG increases the strength of hydrogen bonding between gelatin chains. The appearance of minimum in theTpcurve might be originated from the interplay between self-aggregation via intra-chain concentration at a lowerCgand phase separation via inter-chain association at a higherCg.