Effects of dual‐crosslinking networks on shape memory performance of polynorbornene

Abstract

In this article, Polynorbornene (PNB)/Zinc dimethacrylate (ZDMA)/Dicumyl peroxide (DCP) composites can form dualcrosslinking networks, which contain an ionic crosslinking network, and a part of the C─C covalent crosslinking network. DCP was used to initiate the polymerization of ZDMA to form ionic crosslinking bonds. With the increase of ZDMA, the total crosslink density (V r ) and ionic crosslink density (V r2 ) increased. DCP was consumed in ZDMA polymerization, which made the PNB reduce the covalent crosslinking networks. Leading to the covalent crosslink density (V r1 ) decreased. Compared with covalent crosslinking network, the dual-crosslinking networks stored more energy when deformed, provided better restoring force and a higher shape recovery ratio for materials. When ZDMA exceeded 3.9 wt%, the ZDMA aggregates hindered the movement of molecular chains leading to the shape recovery ratio slightly decreased. When ZDMA was 2.4 wt%, the composite had an optimum shape fixing and shape recovery ratio. This article provided the experimental basis for the research of PNB dual-crosslinking networks, also widened the research of PNB shape memory materials.

Impact of self-assembled structure on ionic conductivity of an azobenzene-containing electrolyte

“…S6 † signies the completion of the thiol-ene click reaction. 26 On the basis of the above results, we deduce that when r Li is below 0.10, the lithium salt rst complexes with oxygen atoms from the ether groups next to azobenzene, and then it begins to complex with oxygen atoms from the ester groups when r Li increases.…”

Relationships of the Degree of C=C Double Bond Conversion with the Dielectric Properties for SiO2/1,2‐PB/SBS/EPDM Composites Cured by Organic Peroxide

“…The measurement of crosslinking density is one of the most efficient methods for revealing structural information on a crosslinked polymer network. The gel content and swelling ratio are usually used to characterize the crosslink density of composite materials [19–21] . In addition, some methods allow one or more reaction groups to be evaluated as a function of time, such as Nuclear magnetic resonance (NMR) spectroscopy, [22–25] attenuation total reflectance Fourier transformation infrared spectrometry (ATR‐FTIR) [26–30] and Raman spectroscopy [31,32] .…”

“…The gel content and swelling ratio are usually used to characterize the crosslink density of composite materials. [19][20][21] In addition, some methods allow one or more reaction groups to be evaluated as a function of time, such as Nuclear magnetic resonance (NMR) spectroscopy, [22][23][24][25] attenuation total reflectance Fourier transformation infrared spectrometry (ATR-FTIR) [26][27][28][29][30] and Raman spectroscopy. [31,32] To date, it seems that there is no study demonstrating the impact of the degree of C=C conversion (DC) on dielectric loss.…”

Dual Covalent Cross-Linking Networks in Polynorbornene: Comparison of Shape Memory Performance

“…Xiao [18] introduced dicumyl peroxide (DCP) in PNB to build a cross-linking network in the PNB matrix, which improved the shape recovery ratio of PNB. Gong [19] prepared polynorbornene/zinc dimethacrylate (ZDMA)/dicumyl peroxide (DCP) composites and explored the effect of a double covalent cross-linking network on the shape memory performance of PNB. It was also found that the double crosslinked network stores more energy during deformation, providing a higher ratio of shape recovery.…”