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  利用疏水相互作用合成的水凝膠通常具有較強(qiáng)的力學(xué)性能和抗溶脹性能，在軟體機(jī)器人、3D打印和可穿戴傳感器等方面具有極大的應(yīng)用前景。然而，疏水相互作用的存在會(huì)使水凝膠內(nèi)部高分子鏈聚集、相互纏結(jié)，形成較大的相分離區(qū)域，限制至其運(yùn)動(dòng)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(xué)反應(yīng)）而很難通過疏水凝膠自身實(shí)現(xiàn)有效的黏附。

  近日，中山大學(xué)化工學(xué)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(qiáng)度的疏水型水凝膠。通過在疏水水凝膠內(nèi)部引入少量的靜電相互作用來減小其內(nèi)部的相分離結(jié)構(gòu)尺寸，賦予凝膠一定的粘彈性。同時(shí),疏水水凝膠本身的高強(qiáng)度和抗溶脹的性質(zhì)得以保留，而凝膠表面的靜電相互作用和疏水締合的協(xié)同作用賦予了凝膠較強(qiáng)的黏附性能。研究表明：在疏水凝膠中引入季銨基團(tuán)與三聚磷酸根的靜電相互作用，不但能夠使水凝膠內(nèi)部相分離區(qū)域尺寸減小，提高凝膠材料的力學(xué)性能，同時(shí)還有利于凝膠內(nèi)部疏水區(qū)域與不同材質(zhì)的基底（玻璃、有機(jī)玻璃、聚丙烯、聚碳酸酯、有機(jī)硅樹脂、聚四氟乙烯等）發(fā)生黏附作用，最大粘附強(qiáng)度達(dá)100kPa。復(fù)合凝膠的這種強(qiáng)粘附和高韌性特性主要來源于凝膠內(nèi)部靜電相互作用和疏水締合的協(xié)同作用。未來可以利用這種復(fù)合結(jié)構(gòu)改善疏水型凝膠材料的粘附和力學(xué)性能，為擴(kuò)大疏水型水凝膠的應(yīng)用提供重要的指導(dǎo)。

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(guān)成果以“Modification of Hydrophobic Hydrogels into a Strongly Adhesive and Tough Hydrogel by Electrostatic Interaction” 為題發(fā)表在Macromolecules 上。論文通訊作者為中山大學(xué)化學(xué)工程與技術(shù)學(xué)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