Thermodynamics incompatibility-driven covalent crosslinking network in situ phase separation from biomimetic design

Abstract

Mussel byssus is an elegant example with high strength and high toughness, inspiring the design of multiphase network structure. At present, many works focus on the design of noncovalent multiphase network. However, such noncovalent bonds (for example, hydrogen bonds) are sensitive to temperature and solvent, which limits the application in the engineering field. To overcome the shortcoming of noncovalent multiphase network, we construct the covalent multiphase network through thermodynamic incompatibility-driven covalent network in situ phase separation. Herein, this work increases the content of sulfur network in the polyolefin matrix. Due to the thermodynamics incompatibility between sulfur network and polyolefin chain, crosslinking network-rich domain and crosslinking network-poor domain appear in the matrix, forming the covalent multiphase network. The improvement in strength can be attributed to the increase in crosslinking density, while the improvement in toughness originates from the preferential rupture of crosslinking network-rich domain. Such covalent multiphase network opens up an innovative strategy for the design of robust materials.