Fabrication of Supramolecular Structured Hydrogels Based on Diels-Alder Click Reaction

Abstract

A novel kind of supramolecular structrued hydrogels were fabricated by Diels-Alder click reaction between furan-functionalized polypseudorotaxanes and polymeric dienophiles. Firstly, polypseudorotaxanes were prepared by supramolecular self-assembly of furan-terminated poly(ethylene glycol)(PEG) and α-cyclodextrins (CDs) in water. And polymeric dienophiles were synthesized by a coupling reaction between copolymer of hydroxyethyl methacrylate and N,N-dimethyl acrylamide and N-maleoyl alanine (AMI). The supramolecular structured hydrogels were prepared by Diels-Alder reaction in water.

Structurally Tunable pH-responsive Phosphine Oxide Based Gels by Facile Synthesis Strategy

“…[26][27][28] Wei et al highlighted the usefulness of Diels-Alder reaction to prepare hydrogels from poly(ethylene glycol) dienophile and polymeric diene. [26][27]29 More recently, Wang et al synthesized antimicrobial hydrogels by incorporating antimicrobial poly-carbonate chains by Michael addition reaction. 28 .…”

“…Design of gels with controlled nanostructures and their response to external stimuli, such as pH, − temperature, , light, ionic strength, , enzymes, chemicals, and combinations of these, has received increasing attention for biomedical applications, smart actuators, and material sciences. − Smart gels can be synthesized from polymers via noncovalent cross-linking or covalent cross-linking . Even though noncovalent gels have a better response time in many applications, covalently cross-linked controlled synthesis is preferred because of the enhanced mechanical properties of gels. − However, the drawback of such gels is the presence of residual monomers, cross-linkers, or catalysts, which impose further complications, that is, sophisticated post purification steps, particularly needed when biomaterials design and the living tissues are involved. , Moreover, uncontrolled cross-linking can result in nonreproducible optical and mechanical properties. , Reaction mechanisms like Diels–Alder and Michael addition reaction having site-specific reactivity and thermal sensitivity can be alternative synthetic strategies in such situations to achieve cleaner gels with tunable structures and functions. − Wei et al highlighted the usefulness of Diels–Alder reaction to prepare hydrogels from poly­(ethylene glycol) dienophile and polymeric diene. ,, More recently, Wang et al synthesized antimicrobial hydrogels by incorporating antimicrobial polycarbonate chains by Michael addition reaction . In most cases, where Michael addition reaction has been used to synthesize gels, a catalyst has been used and their removal from final product is not addressed. − Additionally, gels prepared by these means also involve multiple steps of postmodification and purification. ,− Developing gelators with site-specific reactivity is essential to eliminate multiple intermediate steps and achieve cleaner gels.…”

“…26−28 Wei et al highlighted the usefulness of Diels−Alder reaction to prepare hydrogels from poly(ethylene glycol) dienophile and polymeric diene. 26,27,29 More recently, Wang et al synthesized antimicrobial hydrogels by incorporating antimicrobial polycarbonate chains by Michael addition reaction. 28 In most cases, where Michael addition reaction has been used to synthesize gels, a catalyst has been used and their removal from final product is not addressed.…”