Lossada Francisco, Jiao Dejin, Yao Xuyang, Walther Andreas
A3BMS Lab-Active, Adaptive and Autonomous Bioinspired Materials, Institute for Macromolecular Chemistry, University of Freiburg, Stefan-Meier-Strasse 31, 79104 Freiburg, Germany.
Freiburg Materials Research Center (FMF), University of Freiburg, Stefan-Meier-Strasse 21, 79104 Freiburg, Germany.
ACS Macro Lett. 2020 Jan 21;9(1):70-76. doi: 10.1021/acsmacrolett.9b00997. Epub 2019 Dec 27.
We demonstrate waterborne, unimolecularly dissolved vitrimer prepolymer systems that can be transferred into a vitrimer material using catalytic transesterification. The one-component prepolymer system can be processed via film casting and subsequent heat-induced cross-linking. A variation of the density of side chain hydroxy groups over ester and amide groups in the methacrylate/methacrylamide backbone, as well as of the Lewis acid catalyst loading, allow control of the extent of cross-linking and exchange rates. The increase of the amount of both catalyst and hydroxy groups leads to an acceleration of the relaxation times and a decrease of the activation energy of the transesterification reactions. The system features elastomeric properties, and the tensile properties are maintained after two recycling steps. Thus far, vitrimers have been limited largely to hydrophobic polymers; this system is a step forward toward waterborne, one-component materials, and we demonstrate its use in waterborne bioinspired nanocomposites.
我们展示了一种水性、单分子溶解的玻璃态弹性体预聚物体系，该体系可通过催化酯交换反应转化为玻璃态弹性体材料。单组分预聚物体系可通过流延成膜及随后的热诱导交联进行加工。甲基丙烯酸酯/甲基丙烯酰胺主链中酯基和酰胺基上侧链羟基密度的变化，以及路易斯酸催化剂负载量的变化，可控制交联程度和交换速率。催化剂和羟基数量的增加会导致松弛时间加快，酯交换反应的活化能降低。该体系具有弹性体性能，经过两步回收后仍能保持拉伸性能。到目前为止，玻璃态弹性体主要局限于疏水性聚合物；该体系朝着水性单组分材料迈进了一步，我们展示了其在水性仿生纳米复合材料中的应用。
