NATURE OF WATER IN SYNTHETIC HYDROGELS .1. DILATOMETRY, SPECIFIC CONDUCTIVITY, AND DIFFERENTIAL SCANNING CALORIMETRY OF POLYHYDROXYETHYL METHACRYLATE
NATURE OF WATER IN SYNTHETIC HYDROGELS .1. DILATOMETRY, SPECIFIC CONDUCTIVITY, AND DIFFERENTIAL SCANNING CALORIMETRY OF POLYHYDROXYETHYL METHACRYLATE
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DOI：
10.1016/0021-9797(75)90107-1
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发表时间：
1975-01-01
影响因子：
9.9
通讯作者：
ANDRADE, JD
中科院分区：
文献类型：
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作者：
LEE, HB;JHON, MS;ANDRADE, JD
某些水凝胶中可能存在三种水。我们之前将它们标记为xwater（散装水），Zwater（结合水）和ywater（中间形式，我们称之为界面水）。获得了聚甲基丙烯酸2-羟乙基酯（PHEMA）的体积凝胶电导率数据。计算了比导活化能。活化能与凝胶中水的比例的关系图清楚地指出了三个不同的区域，显示了凝胶中可能存在的三种水。这些结果被热膨胀测量证实。高含水量凝胶（50%）在0°C时表现出非常急剧的体积变化，表明存在正常的散装水。低含水率凝胶（20%）的热膨胀没有异常变化，说明水是结合的。中等含水量凝胶表现出中间行为。对这三类水进行了半定量分析。差示扫描量热法（DSC）研究进一步证实了这些结果。低含水量凝胶（20%）主要由结合水组成，在−15 ~ 24℃范围内无相变。高含水量凝胶在0℃附近发生相变。中等含水量凝胶的相变温度在0℃附近逐渐变化。
Three classes of water may exist in certain hydrogels. We have previously labeled these asXwater (bulk water),Zwater (bound water) andYwater (intermediate forms we call interfacial water). Bulk gel conductivity data for poly (2-hydroxyethyl methacrylate) (PHEMA) were obtained. The activation energy for specific conduction was calculated. A plot of the activation energy versus wt percent of water in the gel clearly indicated three different zones, showing three possible classes of water in the gels. These results were confirmed by thermal expansion measurements. The high water content gels (50%) demonstrated an extremely sharp volume change at 0°C, indicating the presence of normal bulk water. Lower water content gels (20%) showed no anomalous change in thermal expansion, indicating that the water is bound. The medium water content gels exhibited intermediate behavior. A semiquantitative analysis of the three classes of water is presented. A further verification of these results was obtained by differential scanning calorimetry (DSC) studies. The low water content gel (20%) consists mainly of bound water, which exhibited no phase transitions over the range −15 to 24°C. The high water content gels showed phase transitions near 0°C. The medium water content gels show gradual shifts of the phase transition temperatures near 0°C.