Network deconstruction reveals network structure in responsive microgels.
Network deconstruction reveals network structure in responsive microgels.
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DOI：
10.1021/jp111634k
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发表时间：
2011-04-14
期刊：
影响因子：
--
通讯作者：
Lyon LA
中科院分区：
文献类型：
--
作者：
Smith MH;Herman ES;Lyon LA
水凝胶颗粒侵蚀的详细表征揭示了球体之间的关键物理化学差异，其中网络分解是网络结构的信息。通过多角度光散射进行实时，原位监测胶体水凝胶（微凝胶）的触发侵蚀。溶液的平均摩尔质量和根均方半径的侵蚀颗粒作为一个函数的时间由N-异丙基丙烯酰胺（NIPAm）或N-异丙基甲基丙烯酰胺（NIPMAm），与化学不稳定的交联剂（1，2-二羟基乙烯）双丙烯酰胺（DHEA）共聚制备的微凝胶进行测量。采用沉淀聚合来产生尺寸相当但具有不同拓扑特征的颗粒。异构交联剂掺入导致pNIPAm微凝胶的异构网络结构。在腐蚀反应过程中，质量损失从聚合物的外部向内部进行。相比之下，pNIPMAm微凝胶具有更均匀的网络结构，这导致在侵蚀过程中整个颗粒的质量损失更均匀。虽然这两种颗粒类型降解成低摩尔质量的产品，pNIPAm微凝胶不能完全溶解，由于在颗粒合成过程中链转移和支化引起的不可降解的交联的存在。本文所述的观察提供了对与可降解水凝胶颗粒的合成相关的关键设计参数的了解，其可用于各种生物技术应用。
Detailed characterization of hydrogel particle erosion revealed critical physicochemical differences between spheres, where network decomposition was informative of network structure. Real-time, in situ monitoring of the triggered erosion of colloidal hydrogels (microgels) was performed via multiangle light scattering. The solution-average molar mass and root-mean-square radii of eroding particles were measured as a function of time for microgels prepared from N-isopropylacrylamide (NIPAm) or N-isopropylmethacrylamide (NIPMAm), copolymerized with a chemically-labile cross-linker (1,2-dihydroxylethylene)bisacrylamide (DHEA). Precipitation polymerization was employed to yield particles of comparable dimensions but with distinct topological features. Heterogeneous cross-linker incorporation resulted in a heterogeneous network structure for pNIPAm microgels. During the erosion reaction, mass loss proceeded from the exterior towards the interior of the polymer. In contrast, pNIPMAm microgels had a more homogeneous network structure, which resulted in a more uniform mass loss throughout the particle during erosion. Although both particle types degraded into low molar mass products, pNIPAm microgels were incapable of complete dissolution due to the presence of non-degradable cross-links arising from chain transfer and branching during particle synthesis. The observations described herein provide insight into key design parameters associated with the synthesis of degradable hydrogel particles, which may be of use in various biotechnological applications.