Multi-tasking Hydrogels With Self-healing Properties Based On Dynamic Boronic Ester Linkages

Multifunctional and multi-responsive hydrogels have presented a promising platform to design and fabricate smart devices for application in a wide variety of fields.However,significant challenges remain in terms of decreasing synthesis complexity,selecting readily available materials and ensuring excellent versatility and functional multiplexity.In this work,a multifunctional disulfide-containing,boronic acid-based crosslinker bis(phenylboronic acid carbamoyl)cystamine(BPBAC)was readily prepared from inexpensive commercially available 3-carboxylphenylboronic acid(CPBA)and cystamine dihydrochloride,which has the ability to crosslink the cis-diols and catechol-containing hydrophilic polymers to form hydrogels.In the work,the catechol-containing polymers poly(acrylamide-co-dopamine methacrylamide)(P(AM-DOPMA)),Hyaluronic acid-g-dopamine(HA-DOP),(poly(N-isopropyl acrylamide-co-dopamine methacrylamide),P(NIPAM-DOPMA))and the diols-containing polymer polyvinyl alcohol(PVA)were prepared and crosslinked based on the boronate-catechol/diols interactions with BPBAC to prepare multi-responsive hydrogels with double dynamic network.Due to the presence of the reversible and dynamic boronate ester and disulfide bonds,the obtained P(AM-DOPMA),HA-DOP and PVA hydrogels were demonstrated to possess pH,glucose and redox tri-responsive features and autonomic self-healing properties.Besides,because of the inherent heat-responsive property of PNIPAM,the P(NIPAM-DOPMA)hydrogel was endowed with quadruple-stimuli sensitiveness and autonomic self-healing property.The presence of catechol moieties also can render the hydrogel with biomimetic adhesion ability.Moreover,we can modulate the rheological and mechanical properties by simply adjusting the BPBAC or the catechol content in polymer precursor.The features,such as commercially available starting materials,easy-to-implement approach and versatility in controlling crosslinking network and mechanical properties,make the strategy described here a promising platform for fabricating multifunctional and smart hydrogels.