Department of Macromolecular Science and Engineering , Case Western Reserve University , 2100 Adelbert Road , Cleveland , Ohio 44106 , United States.
Institute for Molecular Engineering , University of Chicago , 5640 S. Ellis Avenue , Chicago , Illinois 60637 , United States.
ACS Appl Mater Interfaces. 2018 Sep 12;10(36):30723-30731. doi: 10.1021/acsami.8b10520. Epub 2018 Aug 31.
A series of strong, rebondable polydisulfide nanocomposite adhesive films have been prepared via the oxidation of a thiol-endcapped semicrystalline oligomer with varying amounts of thiol-functionalized cellulose nanocrystals (CNC-SH). The nanocomposites are designed to have two temperature-sensitive components: (1) the melting of the semicrystalline phase at ca. 70 °C and (2) the inherent dynamic behavior of the disulfide bonds at ca. 150 °C. The utility of these adhesives was demonstrated on different bonding substrates (hydrophilic glass slides and metal), and their bonding at both 80 and 150 °C was examined. In all cases, stronger bonding was achieved at temperatures where the disulfide bonds are dynamic. For high surface energy substrates, such as hydrophilic glass or metal, the adhesive shear strength increases with CNC-SH content, with the 30 wt % CNC-SH composites exhibiting adhesive shear strengths of 50 and 23 MPa for hydrophilic glass and metal, respectively. The effects of contact pressure and time of bonding were also investigated. It was found that ca. 20-30 min bonding time was required to reach maximum adhesion, with adhesives containing higher wt % CNCs requiring longer bonding times. Furthermore, it was found that, in general, an increase in contact pressure results in an increase in the shear strength of the adhesive. The rebonding of the adhesives was demonstrated with little-to-no loss in adhesive shear strength. In addition, the 30 wt % nanocomposite adhesive was compared to some common commercially available adhesives and showed significantly stronger shear strengths when bonded to metal.
已通过用不同量的巯基官能化纤维素纳米晶（CNC-SH）对末端含巯基的半结晶低聚物进行氧化，制备了一系列强的、可再交联的多硫化物纳米复合粘合剂膜。这些纳米复合材料设计有两个温度敏感组件：（1）半结晶相在约 70°C 下的熔融，（2）二硫化物键在约 150°C 下的固有动态行为。这些粘合剂在不同的粘合基底（亲水玻璃载玻片和金属）上进行了测试，并检查了它们在 80 和 150°C 下的粘合情况。在所有情况下，在二硫化物键处于动态的温度下，粘合更强。对于高表面能基底，如亲水玻璃或金属，随着 CNC-SH 含量的增加，粘合剪切强度增加，30wt%CNC-SH 复合材料对亲水玻璃和金属的粘合剪切强度分别为 50 和 23MPa。还研究了接触压力和粘合时间的影响。发现需要大约 20-30 分钟的粘合时间才能达到最大粘合强度，含有更高重量%CNC 的粘合剂需要更长的粘合时间。此外，发现一般来说，接触压力的增加会导致粘合剂剪切强度的增加。通过很少或没有损失粘合剪切强度来证明粘合剂的可重新粘合性。此外，将 30wt%纳米复合材料粘合剂与一些常见的市售粘合剂进行了比较，当粘合到金属上时，显示出明显更高的剪切强度。
