Microporous, responsive hydroxypropyl cellulose gels. 1. Synthesis and microstructure
Microporous, responsive hydroxypropyl cellulose gels. 1. Synthesis and microstructure
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DOI：
10.1021/ma970418q
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发表时间：
1998-04-07
期刊：
影响因子：
5.5
通讯作者：
Spontak, RJ
中科院分区：
文献类型：
--
作者：
Kabra, BG;Gehrke, SH;Spontak, RJ
沿着发展了一种有效的微孔凝胶合成技术，并将合成条件与微结构联系起来。这种凝胶具有与它们的无孔类似物基本上不同的性质。将羟丙基纤维素（HPC）水溶液加热到其低临界溶解温度（LCST）以上，同时与二乙烯基砜交联，制备了微孔HPC凝胶。通过将HPC浓度从22.6重量%降低到9重量%，凝胶的有效孔隙率从23增加到76%，如从系统相图所预期的。通过将相分离前的反应时间从1.5分钟增加到25分钟，孔径范围从0.5-9.0 μ m减小到0.05-0.2 μ m，表明在均相状态下的交联限制了可能的相分离的程度。在相分离状态下，通过减少反应时间，凝胶形态从开孔变为闭孔，这限制了富聚合物相中的交联。
An effective technique for the synthesis of microporous gels is developed along with correlations between synthesis conditions and microstructure. Such gels have substantially different properties than their nonporous analogues. Microporous hydroxypropyl cellulose (HPC) gels were prepared by heating aqueous HPC solutions above their lower critical solution temperatures (LCST's) while cross-linking the polymer with divinyl sulfone. The effective porosity of the gel increased from 23 to 76% by decreasing HPC concentration from 22.6 to 9 wt%, as anticipated from the system phase diagram. The pore size range decreased from 0.5-9.0 to 0.05-0.2 mu m by increasing reaction time before phase separation from 1.5 to 25 min, demonstrating that cross-linking in the homogeneous state limits the extent of phase separation possible. Gel morphology changed from open-celled to closed-celled by decreasing reaction time in the phase-separated state, which limits cross-linking in the polymer-rich phase.