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  利用疏水相互作用合成的水凝膠通常具有較強的力學性能和抗溶脹性能，在軟體機器人、3D打印和可穿戴傳感器等方面具有極大的應用前景。然而，疏水相互作用的存在會使水凝膠內部高分子鏈聚集、相互纏結，形成較大的相分離區域，限制至其運動能力。因此，疏水凝膠與基體的黏附往往需要借助其他措施（如溶劑交換、界面化學反應）而很難通過疏水凝膠自身實現有效的黏附。

  近日，中山大學化工學院郭宏磊副教授等通過一步的自由基聚合制備了一種具有高黏附、高強度的疏水型水凝膠。通過在疏水水凝膠內部引入少量的靜電相互作用來減小其內部的相分離結構尺寸，賦予凝膠一定的粘彈性。同時,疏水水凝膠本身的高強度和抗溶脹的性質得以保留，而凝膠表面的靜電相互作用和疏水締合的協同作用賦予了凝膠較強的黏附性能。研究表明：在疏水凝膠中引入季銨基團與三聚磷酸根的靜電相互作用，不但能夠使水凝膠內部相分離區域尺寸減小，提高凝膠材料的力學性能，同時還有利于凝膠內部疏水區域與不同材質的基底（玻璃、有機玻璃、聚丙烯、聚碳酸酯、有機硅樹脂、聚四氟乙烯等）發生黏附作用，最大粘附強度達100kPa。復合凝膠的這種強粘附和高韌性特性主要來源于凝膠內部靜電相互作用和疏水締合的協同作用。未來可以利用這種復合結構改善疏水型凝膠材料的粘附和力學性能，為擴大疏水型水凝膠的應用提供重要的指導。

Fig. 1. Schematics of synthesis of a hybrid hydrogel and strong adhesion performance. (a) An illustration of the networks prepared by copolymerization of cationic monomers and hydrophobic monomers in DMSO solution and subsequently swelling in multivalent phosphate salt solution. The multivalent anions serve as physical cross-linking points to attract polycations in the network. (b) Picture of glass surfaces adhered to a 100 g weight of stainless steel by a p(EA-co-DAC)/STPP hydrogel. (c) Adhesion strength of the pEA, pDAC/STPP, and p(EA-co-DAC_10%)/STPP hybrid hydrogels on a glass substrate, the molar fraction of DAC is 10%. (d) Scheme of the strong adhesion of the p(EA-co-DAC)/STPP hydrogel on a glass substrate: both the hydrophobic sites and electrostatic attractions contribute to the strong adhesion.

Fig. 2. (a) Synthesis of the p(EA-co-DAC_10%)/STPP networks, where STPP physically cross-linked with polymer backbones through intermolecular and/or intramolecular interactions. (b) ATR-FTIR spectra of pEA, p(EA-co-DAC_10%) and p(EA-co-DAC_10%)/STPP hydrogels and STPP salt. (c) Donnan potential profile of p(EA-co-DAC_10%)/STPP hydrogel, the reference solution is NaCl solution with a concentration of 10^-5 mol/L. (d) 1D scattering intensity profiles of pEA, p(EA-co-DAC_10%) and p(EA-co-DAC_10%)/STPP hydrogels.

  相關成果以“Modification of Hydrophobic Hydrogels into a Strongly Adhesive and Tough Hydrogel by Electrostatic Interaction” 為題發表在Macromolecules 上。論文通訊作者為中山大學化學工程與技術學院郭宏磊副教授和郭輝副教授。

  原文鏈接：https://pubs.acs.org/doi/full/10.1021/acs.macromol.1c01115