Tuning the swelling and mechanical properties of pH-responsive doubly crosslinked microgels using particle composition
Tuning the swelling and mechanical properties of pH-responsive doubly crosslinked microgels using particle composition
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DOI：
10.1039/c1sm05922j
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发表时间：
2011-09
期刊：
影响因子：
3.4
通讯作者：
Ruixue Liu;Amir H. Milani;Jennifer M. Saunders;T. Freemont;B. Saunders
中科院分区：
文献类型：
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作者：
Ruixue Liu;Amir H. Milani;Jennifer M. Saunders;T. Freemont;B. Saunders
PH响应型微凝胶颗粒是一种交联的聚合物胶体颗粒，当pH接近pKA时会膨胀。它们吸引了人们的极大兴趣，因为它们能够准备刺激响应性分散。只有一种形式的交联型微凝胶称为单交联型微凝胶(SX微凝胶)。SX微凝胶在这里被定义为包含粒内连接的微凝胶颗粒，作为共价交联物的唯一来源。最近，我们介绍了一种新的pH响应型双交联凝胶(DX微凝胶)家族的第一个例子[Liu等人，Soft Matter，2011，7,4696]。DX微凝胶是由共价连接的官能化SX微凝胶颗粒组成的水凝胶。DX微凝胶既有粒间交联，也有粒内交联。在这里，我们研究了使用一种新的、更通用的微凝胶功能化策略制备的pH响应型DX微凝胶。碳二亚胺化学用于对聚(MMA/MAA/EGDMA)(甲基丙烯酸甲酯、甲基丙烯酸和乙二醇二甲基丙烯酸酯)微凝胶(简称M-EGD)进行乙烯基官能化。通过pH触发甲基丙烯酸2-氨基乙酯(AEM)功能化SX微凝胶的互穿和自由基交联制得DX微凝胶。基于M-EGD的DX微凝胶具有内置的微孔率。此外，动态流变学数据首次表明DX微凝胶的弹性模量与乙烯基官能化程度成正比。以聚(EA/MAA/BDD)(丙烯酸乙酯和1，4-丁二醇二丙烯酸酯)为原料制备了DX微凝胶，简称E-BDD。PH响应型DX微凝胶具有较高的弹性模量值、较强的溶胀性和较低的溶胶率。它们是可注射的，DX微凝胶在低pH值下改善了溶胀，这应该会增加潜在的生物材料应用的pH范围。将这些数据与刘等人报道的数据进行了比较。以及讨论的差异。
pH-Responsive microgel particles are crosslinked polymer colloid particles that swell when the pH approaches the pKa. They have attracted a great deal of interest because of the ability to prepare stimulus responsive dispersions. Microgels that have only one form of crosslinking are termed singly crosslinked microgels (SX microgels). SX microgels are defined here as microgel particles that contain intra-particle linkages as the only source of covalent crosslinks. Recently, we introduced the first examples of a new family of pH-responsive doubly crosslinked microgel (DX microgels) [Liu et al., Soft Matter, 2011, 7, 4696]. DX microgels are hydrogels composed of covalently-linked functionalised SX microgel particles. DX microgels contain inter-particle crosslinking as well as intra-particle crosslinking. Here, we investigate pH-responsive DX microgels prepared using a new, more versatile, microgel functionalisation strategy. Carbodiimide chemistry is used to vinyl-functionalise poly(MMA/MAA/EGDMA) (methyl methacrylate, methacrylic acid and ethyleneglycol dimethacrylate) microgels (abbreviated as M-EGD). The DX microgels were prepared using pH-triggered inter-penetration of 2-aminoethylmethacrylate (AEM) functionalised SX microgels and free-radical crosslinking. The DX microgels based on M-EGD had built-in microporosity. Furthermore, dynamic rheology data show for the first time that the elastic modulus of DX microgels is proportional to the extent of vinyl group functionalisation. The generality of this approach was demonstrated by the preparation of DX microgels based on poly(EA/MAA/BDD) (ethylacrylate and 1, 4-butanediol diacrylate), which is abbreviated as E-BDD. The pH-responsive DX microgels have high elastic modulus values, swell strongly and have low sol fractions. They are injectable and the DX microgels have improved swelling at low pH which should increase the pH range for potential biomaterial applications. The data are compared with those reported by Liu et al. and the differences discussed.