Nano-hybrid self-crosslinked PDMA/silica hydrogels
Nano-hybrid self-crosslinked PDMA/silica hydrogels
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DOI：
10.1039/c0sm00009d
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发表时间：
2010-01-01
期刊：
影响因子：
3.4
通讯作者：
Marcellan, Alba
中科院分区：
文献类型：
--
作者：
Carlsson, Linn;Rose, Severine;Marcellan, Alba
我们发现，在水中的N，N-二甲基丙烯酰胺的自由基聚合可以导致，在一定浓度以上，凝胶没有任何添加的双官能交联剂。这些所谓的“自交联”水凝胶的制备和他们的弱机械性能改善通过引入二氧化硅纳米粒子。从溶胀实验进行平衡在水介质中，它表明，二氧化硅粒子的行为作为粘合剂填料和强烈的相互作用与PDMA链。这些相互作用有助于增强机械性能。从初始弹性模量，确定在制备状态下，我们表明，这些水凝胶的弹性行为主要源于缠结和物理交联，可以控制的聚合物浓度和二氧化硅颗粒和聚合物链之间的比例，分别。的机械性能进行了表征，使用：单调拉伸试验，加载-卸载循环在大应变和应力松弛实验，以调查长期的行为。SiO2的引入大大提高了网络的刚性，但没有降低其延展性，这意味着PDMA链与SiO2表面之间发生了强烈的相互作用，并指出了非线性行为：小变形时软化，大变形时硬化，这与有限的链延展性有关。所有这些效果都显示出强烈依赖于二氧化硅含量。循环引起的滞后和残余应变的分析，清楚地表明，相反的化学交联剂，混合相互作用增加耗散过程。
We discovered that the free radical polymerization of N,N-dimethylacrylamide in water can lead, above a certain concentration, to gels without any added difunctional crosslinker. These so called "self-crosslinked" hydrogels were prepared and their weak mechanical properties were improved by introducing silica nanoparticles.From swelling experiments performed at equilibrium in aqueous media, it was shown that silica particles behave as adhesive fillers and strongly interact with PDMA chains. These interactions are responsible for the reinforcement of mechanical properties. From initial elastic moduli, determined in the preparation state, we show that the elastic behaviour of these hydrogels mainly originates from entanglements and from physical crosslinks that can be controlled by the polymer concentration and the ratio between silica particles and polymer chains, respectively. The mechanical behaviour was characterized using: monotonic tensile tests, loading-unloading cycles at large strains and stress relaxation experiments in order to investigate long time behaviour. The introduction of silica highly increases the stiffness of the network without greatly reducing its extensibility, implying that strong interactions take place between PDMA chains and silica surfaces.Non-linear behavior was pointed out: softening at small deformations and hardening at high deformations which is related to finite chain extensibility. All these effects have been shown to strongly depend on the silica content. The analysis of hysteresis and residual strains induced by cycles, clearly indicate that contrary to chemical crosslinkers, hybrid interactions increase the dissipative process.