Study On Starch Hydrogen Bond Enhancement And High Adhesion Hydrogel

Hydrogels are widely used biomaterials with attractive features,including high water content,high deformability,structural similarity to biological tissues,and potential functionalization.For many applications,such as underwater soft robots,implantable devices in human body,wound dressing,tissue engineering,and drug delivery systems,hydrogels are required to adhere firmly to substrate surfaces in both dry and wet environments.In this study,amylopectin?Amy?,a dendritic polyhydroxy natural polymer,was introduced into the hydrogels:weak-strong-hydrogen-bond crosslinked amylopectin/polyacrylamide/poly?vinyl alcohol?double network?Amy/PAAm/PVA DN?hydrogels and"soft-hard"hydrogen-bonded crosslinked amylopectin/poly?N-hydroxyethyl acrylamide??Amy/PHEAA?DN hydrogels were prepared,and explored their high strength mechanical properties and adhesion properties.Our design strategy is to use hydroxyl-abundant dendritic polymer Amy as a multiple hydrogen bonding crosslinker to construct and reinforce the fully physically crosslinked PAAm/PVA double network?DN?hydrogel networks for desired bulk mechanical properties,and meanwhile,to enhance the interactions between the hydrogel networks and non-porous substrates for desired interfacial mechanical properties.The Amy/PVA/PAAm DN hydrogels exhibited high tensile strength?854.1 kPa?,high extensibility?ca.8 times?,high bulk toughness(4094.8 kJ m^-3),good self-recovery property?ca.92%of self-recovery at room temperature?,and strong adhesion to nonporous glass surfaces?ca.158 kPa?.Amy/PHEAA DN hydrogel,where both networks were hydrogen bonding crosslinked,not only had super toughness,but also were able to strongly adhere to wet soft materials.The"soft-hard"hydrogen-bonded crosslinked Amy/PHEAA DN hydrogel exhibited high tensile strength?357.9 kPa?,high extensibility?1100%?,good elastic modulus?299.5 kPa?,and high bulk toughness(2071.1 kJ m^-3).Through adjustment of hydrogen bond density,strong and tough hydrogels were prepared that exhibited different levels of adhesion strength and three adhesive failure mechanisms.We replaced Amy with oxidized starch?OSA?to synthesize dual and hybrid chemically/physically crosslinked OSA/PHEAA DN hydrogels that were capable of forming Schiff's bases at hydrogel-hydrogel or hydrogel-tissue interfaces,aside from interfacial H-bonding,incurring sustained,high interfacial toughness(1850 J m^-2hydrogel-hydrogel and 610 J m^-2 hydrogel-tissue)in wet environments.