Multi-recyclable Shape Memory Supramolecular Polyurea with Long Cycle Life and Superior Stability

Abstract

Shape memory polymers (SMPs) have attracted a wide range of interest owing to their technological impact. It remains a great challenge to construct SMPs with both excellent shape memory recoverability and durability and satisfactory reprocessability. Herein, by incorporating low-content noncovalently bonded linkers into the covalent network of SMP, a shape memory supramolecular polyurea (SMSP) with excellent reprocessability and shape memory properties has been successfully constructed. The SMSP was endowed with remarkable shape memory performance and solvent resistance owing to its covalent cross-linking. It displayed outstanding shape memory cycle stability with above 92.7% of shape recovery ratio even after 20 consecutive shape memory cycles. In addition, SMSP could be recycled for 7 times without clear decline in mechanical properties, exhibiting excellent multiple reprocessability. It is anticipated that this work will provide a new insight into designing SMPs with excellent reprocessability and cycle stability.

Super Strong and Multi-Reusable Supramolecular Epoxy Hot Melt Adhesives

“…According to the above strategy of molecular design, we constructed a novel supramolecular epoxy hot melt adhesive (SEA) via incorporating flexible side chains into the network of highly noncovalently cross-linked epoxy resins. Epoxy-based adhesives are widely applied owing to their desirable adhesive properties, low curing shrinkage, and excellent thermal stability. , Conventional epoxy-based adhesives are two-component thermoset adhesives mainly, though there are a few reports on one-component epoxy hot melt adhesives. ,, As shown in Scheme a, the self-complementary quadruple hydrogen-bonded ureidopyrimidinone (UPy) motif, which features a high dimerization constant and can noncovalently interact with diverse substrates, − acted as noncovalent cross-linkers, − while the polypropylene glycols functioned as chain extenders and flexible side chains. The SEA was prepared through polycondensation of diglycidyl ether of bisphenol A (DGEBA) with O -(2-ureido-4­[1H]-pyrimidinone)- O ′-(2-aminopropyl)­polypropylene glycol (UPy-PPG-NH 2 ) and O -(2-aminopropyl)- O ′-(2-methoxyethyl)­polypropylene glycol (Me-PPG-NH 2 ).…”

High temperature shape memory poly(amide-imide)s with strong mechanical robustness

“…Apparently, creep is detrimental to the temporary network because a temporary shape is generally programmed under an external force. 37,44 Tensile creep behaviour of the resulting PAIs was evaluated by using DMA under 5 MPa load respectively at 180, 200 and 220 °C. The creep recovery curves are shown in Fig.…”

“…The hydrogen bonding interaction has been proven to be quite efficacious for pursuing desirable SME in a few polymers. 3,[42][43][44] In the current poly (amide-imide) networks, the temperature-dependent association constant of the hydrogen bonding serves as reversible interactions to activate and freeze the segmental mobility, while the rigid polyimide framework inhibits long-range chain-chain slippage, consequently providing satisfactory shape memory behavior and excellent engineering performance.…”

Supramolecular polymer networks crosslinked by crown ether-based host–guest recognition: dynamic materials with tailored mechanical properties in the bulk

“…One of the most potential applications of SPNs is in the preparation of tough hydrogels and elastomers. [4][5][6][7][8][9][10][11][12][13] In the networks, a large number of noncovalent bonds serving as sacrificial bonds are able to dissociate before the breaking of covalent bonds of the backbones, 12,[14][15][16][17] and the dissociated dynamic bonds can reform reversibly. Such a process increases the energy needed to break the materials, representing an efficient toughening mechanism.…”