Effects of regular networks composed of rigid and flexible segments on the shape memory performance of epoxies

A series of regular rigid flexible cross-linking epoxy networks were prepared from dithiol ally] glycidyl ethers (DTAGEs) and 4,4'-diaminodiphenylmethane (DDM). In these networks, the chemical structure of DTAGEs was tidily flexible and that of DDM was simply rigid, which ensured the flexible segments were more distinguishable from the rigid units. The effects of regularity and rigid-flexible character of the networks on shape memory properties, especially shape recovery speed, were investigated in detail. It was found that the shape recovery speed was reversely proportional to the flexibility of the regular cross-linking networks. Compared with flexibility, regularity had a greater impact on the recovery speed. In addition, regularity had a significant influence on the recovery speed of the rigid units while it had little influence on that of the flexible segments. The well-designed regular rigid-flexible cross-linking networks exhibited excellent shape memory performance with high shape memory fixity (>= 98.4%) and shape memory recovery (>= 99.4%).