A Facile Strategy To Construct PDLLA-PTMEG Network with Triple-Shape Effect via Photo-Cross-Linking of Anthracene Groups

Abstract

Covalently cross-linked network has been widely applied in triple-shape memory polymers (TSPs), and fabricating triple-shape memory networks with the optional shapes through a facile and fast way is highly expected in the real applications. In this study, a "preshaped and post-cross-linking" strategy has been put forward to fabricate the triple-shape networks via fast photo-cross-linking in solid state. The photoresponsive anthracene group was first employed to develop a poly(D,L-lactide)−poly(tetramethylene oxide) glycol (PDLLA-PTMEG) network via UV light irradiation. Two steps were involved in network fabrication: first, linear copolymers (AN-PDLLA-PTMEG) containing anthracene groups on the side chains with different mass ratio of PDLLA segments were synthesized, and then PDLLA-PTMEG networks (NW-PDLLA-PTMEG) were formed by 365 nm UV light irradiation under an argon atmosphere. The structures of all the precursors were determined by 1 H NMR, and all networks were evaluated by swelling tests. The results of tensile tests show that the content of PDLLA segments has a crucial effect on the mechanical performance of the materials. Differential scanning calorimetry (DSC) analysis combined with dynamic mechanical analysis (DMA) reveals that all the NW-PDLLA-PTMEG's display two thermal transitions (T m,PTMEG and T g,PDLLA ), which can be utilized as T trans to trigger triple-shape memory behavior. The cyclic thermal mechanical testing for triple-shape effects of NW-PDLLA-PTMEG, which was performed by DMA, demonstrates that the mass ratio of two segments has a great effect on the shape fixity and shape recovery. Moreover, a practical application as heat-shrinkable tube (or film) has been put forward.

Blends of poly(ester urethane)s and polyesters as a general design approach for triple‐shape memory polymers

“…This can be achieved by combining two crystallizable, amorphous, or liquid crystalline components or combinations thereof. 22,[27][28][29][30][31][32][33] Specific examples include linear copolymers, such as polyurethanes containing crystalline poly(caprolactone) and poly(tetramethylene ether) glycol segments, methacrylate copolymers featuring multiple glass transitions, 34,35 polymeric networks based on poly(caprolactone) and poly(cyclo-hexylmethacrylate), poly (d,l-lactide) and poly(tetramethylene oxide) glycol, or cross-linked poly(caprolactone)-based polyurethane, 26,[36][37][38] interpenetrated networks, such as poly(ε-caprolactone)poly(p-dioxanone), or composites formed by the thiol-Michael addition reactions of thiols and vinyls/acrylates with two narrow glass transitions. 39,40 Another possibility is the creation of multicomponent objects, such as bilayer films that consist of two dual-shape memory polymers.…”

A dual‐induced self‐expandable stent based on biodegradable shape memory polyurethane nanocomposites (PCLAU/Fe3O4) triggered around body temperature

“…No melting peaks of PTMEG segments were observed due to the incorporation of PCLA segments and low loading content of PTMEG. PCLA segments not only destroyed the regularity of the PTMEG chains seriously, but also sharply restricted the chain movement of PTMEG segments …”

Coumarins into Polyurethanes for Smart and Functional Materials

“…Following the main line of the present review, photochemical activation is probably one of the most used mechanisms in this issue, due to a wide variety of available photoreactive molecules and spatial control, allowing us to selectively irradiate some regions against others. Since the implementation of this methodology, the first efforts focused on preparing polyurethanes carrying other photoreactive probes, such as anthracenes [123,124], cinnamates [125] and azo-benzenes [126]. On the other hand, coumarins have been inserted into other polymer systems such as PVA [127] or polyesters [128][129][130], achieving very encouraging results.…”