高强度纤维素双网络导电水凝胶制备及其应变感应特性研究

Preparation and Strain Induction Characterization of High Strength Cellulose Dual-network Conductive Hydrogel

将微晶纤维素(MCC)-氢氧化钠/尿素溶液通过乙醇蒸气诱导形成纤维素一级网络,以丙烯酸(AA)和丙烯酰胺(AM)为原料,N,N′-亚甲基双丙烯酰胺(MBAA)为交联剂,过硫酸铵(APS)为引发剂构建二级网络,随后采用浸泡法引入氯化铁,构筑了多交联的纤维素/聚丙烯酰胺-聚丙烯酸/铁离子(C/PAMAA/Fe^(3+))水凝胶,并对水凝胶的力学性能及电化学性能进行了探究。研究结果表明:Fe^(3+)与—COO^(-)形成的配位键在形变时作为牺牲键断裂,这有助于C/PAMAA/Fe^(3+)机械性能的提升,水凝胶的韧性和抗拉强度分别达到17.13 MJ/m^(3)和4.59 MPa。循环拉伸测试的结果显示:随着Fe^(3+)浓度的增加,C/PAMAA/Fe^(3+)水凝胶的能量耗散效率增加,从56.86%增加到75.17%,且第二次循环后弹性恢复率接近85.0%。随着Fe^(3+)用量的增加,离子电导率增大,Fe^(3+)浓度为0.2 mol/L的C/PAMAA/Fe^(3+)水凝胶电导率为1.03 S/m。将C/PAMAA/Fe^(3+)水凝胶组装为应变感应器,感应器的灵敏度为4.0,其拉伸递增和拉伸循环的电阻变化结果表明该应变感应器具有较好的稳定性;实时监测关节活动的结果表明该感应器具有稳定的应变响应性。

The primary network was formed by using ethanol vapor to induce the microcrystalline cellulose(MCC)-sodium hydroxide/urea solution.The acrylic acid(AA)and acrylamide(AM)were chosen as raw materials,together with N,N′-methylene bisacrylamide(MBAA)as a cross-linking agent,and ammonium persulfate(APS)as an initiator to fabricate the secondary network.Then,ferric chloride was introduced by soaking method to construct a multi-crosslinked cellulose/polyacrylamide-polyacrylic acid/iron ion hydrogel(C/PAMAA/Fe^(3+)).The mechanical and electrochemical properties of the hydrogel were investigated.The results showed that the coordination bond formed by Fe^(3+)and—COO^(-)acted as a sacrificial fracture during deformation,which contributed to the improvement of the mechanical properties of C/PAMAA/Fe^(3+).The hydrogel showed the toughness of 17.13 MJ/m^(3) and tensile strength of 4.59 MPa,respectively.Moreover,the results of the cyclic tensile loading-unloading test showed that the energy dissipation efficiency of the C/PAMAA/Fe^(3+)hydrogel increased with the increase of Fe^(3+)concentration,and the energy dissipation rate increased from 56.86%to 75.17%.Besides,the elastic recovery after the second cyclic loading-unloading could reach around 85.0%.As the increasing concentration of Fe^(3+),the ionic conductivity of the C/PAMAA/Fe^(3+)hydrogel increased,and a Fe^(3+)concentration of 0.2 mol/L was 1.03 S/m.The C/PAMAA/Fe^(3+)hydrogel was assembled as a strain sensor,and the sensitivity was 4.0.The resistance change results of the stretching increment and stretching cycle showed that the C/PAMAA/Fe^(3+)hydrogel strain sensor had good stability.The results of real-time monitoring of joint activities showed that the sensor had a stable strain response.