Tuning the Swelling Properties of Smart Multiresponsive Core-Shell Microgels by Copolymerization
Tuning the Swelling Properties of Smart Multiresponsive Core-Shell Microgels by Copolymerization
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DOI：
10.3390/polym11081269
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发表时间：
2019-08-01
期刊：
影响因子：
5
通讯作者：
Hellweg, Thomas
中科院分区：
文献类型：
--
作者：
Braendel, Timo;Dirksen, Maxim;Hellweg, Thomas
本研究致力于开发多响应核壳微凝胶，并通过不同的丙烯酰胺--特别是N-异丙基丙烯酰胺(NIPAM)、N-异丙基甲基丙烯酰胺(NIPMAM)、N-异丙基甲基丙烯酰胺(NNPAM)--与丙烯酸的共聚来调控其溶胀性能。我们使用原子力显微镜对微凝胶颗粒的干态进行表征，并使用光子相关光谱研究微凝胶在中性(PH 7)和酸性(PH 4)条件下的溶胀行为。观察到具有纯聚N，N-丙基丙烯酰胺(PNNPAM)壳的微凝胶的互穿网络结构与具有纯聚N-异丙基甲基丙烯酰胺(PNIPMAM)壳的微凝胶具有明显的核-壳结构之间的转变。壳层中PNIPMAM的摩尔分数对粒子的刚性也有重要的影响，因为互穿程度降低。此外，微凝胶的溶胀行为可以通过调节单步体积相变和线性溶胀区域之间的pH值来调节，温度与壳层的共聚比例相对应。这种柔韧性使多响应性共聚微凝胶成为许多应用的候选材料，例如，作为具有可调渗透性的膜材料。
The present study focuses on the development of multiresponsive core-shell microgels and the manipulation of their swelling properties by copolymerization of different acrylamides-especially N-isopropylacrylamide (NIPAM), N-isopropylmethacrylamide (NIPMAM), and NNPAM-and acrylic acid. We use atomic force microscopy for the dry-state characterization of the microgel particles and photon correlation spectroscopy to investigate the swelling behavior at neutral (pH 7) and acidic (pH 4) conditions. A transition between an interpenetrating network structure for microgels with a pure poly-N,n-propylacrylamide (PNNPAM) shell and a distinct core-shell morphology for microgels with a pure poly-N-isopropylmethacrylamide (PNIPMAM) shell is observable. The PNIPMAM molfraction of the shell also has an important influence on the particle rigidity because of the decreasing degree of interpenetration. Furthermore, the swelling behavior of the microgels is tunable by adjustment of the pH-value between a single-step volume phase transition and a linear swelling region at temperatures corresponding to the copolymer ratios of the shell. This flexibility makes the multiresponsive copolymer microgels interesting candidates for many applications, e.g., as membrane material with tunable permeability.