Self-healable and recyclable triple-shape PPDO–PTMEG co-network constructed through thermoreversible Diels–Alder reaction

Abstract

Based on Diels-Alder reaction, linear bisfuranic terminated poly(tetramethylene oxide) and poly(p-dioxanone) were crosslinked by tris(2-maleimide ethyl)amine; this process was fully reversible under moderate conditions. All of the results indicate that the conetwork possesses the typical advantages of chemical and physical crosslinking, peculiar thermal invertibility, shape memory effect and self-healability.As a most promising intelligent material, shape memory polymers (SMPs) have the capability of changing the shape in response to various external stimuli. 1-3 This characteristic offers SMPs a wide range of applications. 4-7 Conventionally, thermally induced SMPs with one thermally reversible transition can only memorize one temporary shape on a single shape memory cycle, named dual-shape memory polymers. 8 To widen the application of shape memory polymers, different types of SMPs were synthesized. 9-16 The multishape memory effect, referring to the ability of SMPs to memorize at least two temporary shapes in only one shape memory cycle, is currently attracting considerable interest due to its ability to provide an additional dimension to the technical potential of SMPs. Actually, multi-shape memory effects are achievable simply by introducing an additional reversible phase transition, which has been experimentally demonstrated 13 and theoretically proved. 14 From a molecular design standpoint, it is not an arduous task to introduce two distinctive and reversible phases into a polymer to achieve a triple-shape polymer. SMPs meeting this requirement have been reported and the two T trans are T m and T g of SMPs. However, they all have one thing in common: the original shape is defined by netpoints resulting from the chemical crosslinking, 13-20 which is more durable due to its stronger network structure of covalent bonds, and it can result in the SMPs exhibiting excellent shape memory properties such as higher shape recovery and higher fixity ratios compared with physically crosslinked SMPs. 1,19-22 But there is a requirement to address the problem of the chemically crosslinked SMPs, that is, they are not easy to be reprocessed, which would limit the list of applications of shape memory polymers. We therefore designed and developed a novel triple-shape network based on thermally reversible chemical crosslinking. At least two different polymer segments were introduced to build the network with separated switching domains which were associated with two individual transition temperatures (T g or T m ), dominating the temporary shape B and shape C, respectively. The crosslinking determined the permanent shape A.Unlike the traditional triple-shape network, in this work, thermally reversible Diels-Alder (D-A) cycloaddition 22-24 was selected to crosslink the linear bisfuranic terminated poly(tetramethylene oxide) (PTMEG-BF) and poly(p-dioxanone) (PPDO-BF) with tris(2-maleimide ethyl)amine, considering that not only PPDO 25,26 and PTMEG 27 have outstanding biocompatibility, which makes them good candidates for biomate...

Recent progress in shape memory polymer: New behavior, enabling materials, and mechanistic understanding

“…This was demonstrated by Yang and coworkers [184]. Whereas the two T m s from PTMEG and PPDO provided the basis for a triple-SME, heating to a higher temperature allowed decrosslinking for reprocessing via the reverse Diels-Alder reaction.…”

Hydrolytic degradation behaviors of poly(p-dioxanone) in ambient environments

“…With the great progress in the research and development, PPDO can also be widely used as general materials in ambient environments [11,12,17] . In fact, the hydrolytic degradation of PPDO not only occurs in vivo, but also takes place in ambient environments.…”

Functional self-healing materials and their potential applications in biomedical engineering

“…Readhesion between the cut surfaces of the hydrogel was observed after 24 h at room temperature. Supramolecular networks embedding crown ether-based host-guest moieties were also reported to fabricate this type of hydrogel [33,81]. Sol-gel transition of this type of self-healing hydrogels can be triggered by pH variation due to pH-dependent host-guest interactions (Fig.…”

“…Reversible non-covalent interactions and dynamic covalent bonds are the two most common self-healing strategies employed in intrinsic self-healing materials (Table 1). Reversible physical interactions such as hydrogen bonds, hydrophobic interactions, ionic interactions, π-π stacking, and host-guest interactions have been used to play the major role in the stimulus-responsive healing process of self-healable rubber, film, and hydrogels [11,26,33,[35][36][37][38][39][40][41][42][43][44][45][46][47]. Compared to non-covalent interactions, relatively strong dynamic covalent bonds introduce both structural stability and higher mechanical strength into intrinsic self-healing materials.…”