Polymer Research Centre, Department of Chemical Sciences, Indian Institute of Science Education and Research , Kolkata, PO: BCKV Campus Main Office, Mohanpur 741252, Nadia, West Bengal, India.
J Phys Chem B. 2013 Dec 19;117(50):16292-302. doi: 10.1021/jp408164y. Epub 2013 Dec 10.
Thermoresponsive poly(2-(2-methoxyethoxy)ethyl methacrylate) (PMEO2MA) based hybrid nanocomposite hydrogels (NCH) were synthesized by dispersing preformed cadmium sulfide (CdS) quantum dots (QDs) in the reaction mixture followed by polymerization via reversible addition-fragmentation chain transfer (RAFT) technique. High doping capacity and negligible QDs leakage were observed for hydrophilic QDs doped hydrogels (hpl-NCH) due to H-bonding interactions between QDs and pendant groups of hydrogel network. The hpl-NCH networks showed improved structural/orientational order and swelling ratios with increasing doping concentration compared to the organic hydrogel (OH). Opposite trends were observed for bulk-CdS (NCH-bulk) and 1-dodecanethiol capped CdS (NCH-DDT) doped hydrogels. Swelling induced linear retardance and quenching of photoluminescence (PL) intensity for hydrogels were exploited to study the deswelling kinetics respectively by Mueller matrix polarimetry and solid state fluorimetry, which were further corroborated with gravimetric analysis. For all the NCH, deswelling process significantly decreased with increasing temperature, which followed the order: 30 > 45 > 60 °C. Slower deswelling was observed for NCH-bulk and hpl-NCH compared to the OH, and also with increase in doping concentration due to the formation of skin layer. However, NCH-DDT exhibited accelerated deswelling process and the order was reversed with respect to doping concentration due to DDT mediated enhanced hydrophobic aggregation and water leakage channels created by long hydrophobic free-mobile nature of QDs surface tethered DDT molecules. The presented methodology provides tunable deswelling of PMEO2MA based hydrogels by doping with hydrophilically/hydrophobically modified CdS QDs.
基于聚（2-（2-甲氧基乙氧基）乙基甲基丙烯酸酯）（PMEO2MA）的温敏性杂化纳米复合水凝胶（NCH）是通过将预先形成的硫化镉（CdS）量子点（QDs）分散在反应混合物中，然后通过可逆加成-断裂链转移（RAFT）技术聚合而合成的。由于 QDs 和水凝胶网络支链上的基团之间存在氢键相互作用，因此掺杂水凝胶（hpl-NCH）中具有高的掺杂容量和可忽略不计的 QDs 泄漏。与有机水凝胶（OH）相比，hpl-NCH 网络具有更高的结构/取向有序性和溶胀比，随着掺杂浓度的增加而增加。对于 bulk-CdS（NCH-bulk）和 1-十二硫醇封端的 CdS（NCH-DDT）掺杂水凝胶，观察到相反的趋势。水凝胶的溶胀诱导线性延迟和光致发光（PL）强度猝灭被用来分别通过穆勒矩阵偏振法和固态荧光法研究解吸动力学，这与重量分析进一步证实。对于所有的 NCH，解吸过程随温度的升高而显著降低，顺序为：30 > 45 > 60°C。与 OH 相比，NCH-bulk 和 hpl-NCH 的解吸过程较慢，并且随着掺杂浓度的增加而减慢，这是由于形成了皮层。然而，NCH-DDT 表现出加速的解吸过程，并且与掺杂浓度有关，这是由于 DDT 介导的增强的疏水性聚集和由 QD 表面连接的 DDT 分子的长疏水性自由移动性质产生的水泄漏通道所致。所提出的方法通过掺杂亲水性/疏水性修饰的 CdS QDs 提供了对 PMEO2MA 基水凝胶的可调解吸。
