Creating Poly(tetramethylene oxide) Glycol-Based Networks with Tunable Two-Way Shape Memory Effects via Temperature-Switched Netpoints

Abstract

Polymers with two-way shape memory effect (2W-SME) are of great potential in real applications due to the reversible nature. Though 2W-SME has been already realized in some semicrystalline networks by the crystallization-induced elongation (CIE) and melting-induced contraction (MIC), more adaptable 2W-SME systems are highly expected. In this work, to achieve tunable 2W-SME with different reversible deformation ranges, we designed a semicrystalline poly-(tetramethylene oxide) glycol (PTMEG) network with temperature-switched netpoints. This adaptable network was constructed by photo-cross-linking of the PTMEG-based copolymer containing amorphous poly(D,L-lactide) (PDLLA) segments in main chain and photosensitive anthracene groups in side chain. The photo-cross-linking degrees of networks were adjusted by controlling irradiation time. Remarkably, 2W-SME in the current system was realized by the CIE and MIC of PTMEG segments for the first time. Here, along with the photo-cross-links, the low content of PDLLA served as a switchable netpoint which was controlled by high temperature (T high ). Differential scanning calorimetry (DSC) analysis revealed that all the photo-cross-linked networks exhibited desirable crystallinity. Dynamic mechanical analysis (DMA) indicated that there were two distinct declines of storage modulus (E′) when temperature crossed T m,PTMEG and T g,PDLLA , which guided us to choose 45 and 70 °C as two specific T high s. 2W-SME was investigated by DMA under constant stress; in detail, the effects of applied stress, T high , and photo-cross-linking degree synergizing with the switchable netpoints structure on the characteristics of 2W-SME (ε i , ε Non-CIE , ε CIE , R act (σ), and R rec (σ)) have been disclosed.

Light- and heat-triggered reversible luminescent materials based on polysiloxanes with anthracene groups

“…Anthracene groups undergo dimerization ([4 + 4] cycloaddition reaction) when irradiated by UV (l > 300 nm). 26 In this study, the photo-cycloaddition between the anthracene groups was accomplished through UV-irradiation at 365 nm. In order to conrm the effectiveness of dimerization under the UV light, the control experiments were performed using 9-anthracenylmethyl acrylate or anthracene-9-carboxylic acid under the same conditions.…”

“…[12][13][14][15][16][17][18][19][20][21][22] Anthracene groups undergo [4 + 4] photo-dimerization when irradiated by UV light (l > 300 nm) and can be reversed to the original monomers via exposure to a higher energy UV light (l < 300 nm) (Scheme 1) 23 or heating to 100-130 C. 24,25 Xie et al successfully obtained shape-memory materials by dangling photoresponsive anthracene groups from different polymer chains. 23,26,27 However, there are few reports on reversible silicone elastomers based on the anthracene groups.…”

Applications of Shape Memory Polymers in Kinetic Buildings

“…However, fabricating appropriate twoway SMPs can be difficult. A novel polymer fabrication process using 3D printing has recently emerged [77,87,[90][91][92]. 3D printing is capable of producing advantageous complex structures.…”

“…3D printing is capable of producing advantageous complex structures. With the help of SMPs, 3D printed materials are able to respond to and change shape with a stimulus and this is called 4D printing (selfenveloping/self-folding) [77,87,90,91]. is 4D printing technique was first presented in a water solution but was nonreversible [93].…”

Combined light- and heat-induced shape memory behavior of anthracene-based epoxy elastomers

“…Anthracene molecules exhibit a reversible dimerization reaction enabled by a [4 + 4] cycloaddition when exposed to UV light with wavelengths higher than 300 nm and a scission of the crosslinked dimers when exposed to UV light with wavelengths lower than 300 nm or temperature above 120 °C 26 . Based on this mechanism, anthracene has been incorporated into a variety of polymers as pendant groups to realize light-controlled shape memory behavior, including poly( l -lactide) (PLA) 27 , poly(ethylene glycol) (PEG) 28 , poly( d , l -lactide) (PDLLA) 29 , poly(tetramethylene oxide) glycol (PTMEG) 30 . These anthracene-functionalized polymers showed effective shape fixation and recovery when irradiated by 365 nm and 254 nm UV light, respectively, which was ascribed to the photodimerization and scission of the pendant anthracene groups.…”