Preemptive Healing through Supramolecular Cross-Links

Abstract

The ability of highly cross-linked thermoset materials to relax stresses by network chain segment mobility above or just below T g is generally limited. We describe materials in which some of the crosslinks have been replaced by dimers of quadruple hydrogen-bonding ureidopyrimidinone (UPy) moieties, which act as reversible cross-links. Materials based on mixtures of ε-caprolactone and L-lactic acid, and containing different ratios of covalent and UPy dimer cross-links, were synthesized, and their thermal and mechanical properties were tested by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The presence of reversible cross-links results in superior relaxation of stresses even below T g , as witnessed by the creep and stress relaxation behavior. These properties bode well for potential applications, e.g., in coatings technology.

Self-replenishing ability of cross-linked low surface energy polymer films investigated by a complementary experimental-simulation approach

“…4,5 In fact, selfhealing is currently one of the most active topics in materials science. [6][7][8] For polymers [9][10][11] and polymer coatings [12][13][14][15] several approaches have been reported to restore the integrity of the material, either by refilling the damaged areas, e.g., a) Electronic addresses: a.c.c.esteves@tue.nl and g.dewith@tue.nl via encapsulated reactive components (autonomous healing) or by reestablishing chemical bonds through reversible reactions triggered by external stimuli such as temperature, light or a pH switch (triggered healing). These approaches can use intrinsic healing concepts, [16][17][18][19] in which the healing agent is inherent to the material (i.e., is a part of the network or formulation) or extrinsic healing, where external components are added, such as filled capsules [20][21][22][23] or microvascular networks.…”

LED-cured self-replenishing hydrophobic coatings based on interpenetrating polymer networks (IPNs)

“…One way to address this issue is to introduce a self-healing mechanism, which has received wide interest both from academia and industry in the last decades. [23][24][25][26][27] For polymers and polymer coatings, most reported self-healing approaches, such as encapsulation, 28,29 reversible bonds/interactions [30][31][32][33][34][35][36][37][38][39][40][41][42] or deformation recovery 43,44 aim at repairing mechanical properties or material integrity. Much less attention has been paid to self-healing mechanisms aiming to recover surface functionalities.…”

Thermosetting bismaleimide resins generating covalent and multiple hydrogen bonds

“…However, there are a few studies on polymer networks having both covalent and MHB cross-linkages. 18, 19 Wietor et al partially replaced covalent urethane cross-linkages formed by the reaction of a trihydroxy-terminated three-armed flexible aliphatic polyester and diisocyanate to UPy-based multiple hydrogen bonds. They found that the incorporation of the UPy units improves the mechanical strength.…”

“…They found that the incorporation of the UPy units improves the mechanical strength. 18 However, it is not explored whether this strategy is applicable to high-performance thermosetting resins.…”