| Gel materials are three-dimensional networks which can retain a large amount of solvent in their swollen state.As an important research fields for gel materials,hydrogels possess excellent optical transparency,viscoelasticity and biocompatibility.Nevertheless,traditional hydrogels suffer from unsatisfactory mechanical properties and simple functions,which greatly restrict the further applications.Hence,introducing multiple dynamic crosslinking into the three-dimensional networks to prepare smart hydrogels with high mechanical strengths,self-healing,shape memory and self-adhesion based on efficient energy dissipation mechanism has become one of the hotspots in interdisciplinary research fields.Additionally,the current artificial hydrogels are generally short of highly flexibility and adaptability due to their homogeneously hydrophilic structures,which highly impedes their practical applications in complex and harsh circumstances.Consequently,developing the next-generation gel materials with highly environmental adaptability is both a challenge and an opportunity.This thesis is mainly constructed by two parts.In the first part,based on constitutional dynamic chemistry,we focused on designing smart hydrogel networks with stretchability,self-healing,self-adhesion and thermoplasticity comprising of synergistic effect of physical crosslinking and dynamic covalent linkages,which exhibited potential applications in fields of biomedicine and flexible electronics.In the second part,based on binary cooperative complementary principle,we aimed to develop organohydrogels with elaborate heterostructures and desirable environmental adaptabilities,such as freezing tolerance,long-term stability,underwater adhesion,and switchable wettability,which further realized the engineering application of gel materials in complex circumstances.The main contents of this thesis are as follows:Chapter ?:Introduction.Based on the basic concept of the gel materials,the various types and constructing mechanism of the existing gels were systematically introduced.We briefly described the development history of hydrogels and the breakthroughs in the performance optimization.The relevant construction rules and application exploration of various smart hydrogels were also summarized.Inspired by the exquisite microstructures and extraordinary environmental adaptability of biological organisms,we summarized the construction rules and functional advantages of various organohydrogels with heterogeneous networks based on binary cooperative complementary principle to break through the limitations of artificial homogeneous gels.Starting from the research frontiers,we presented the research purpose,contents and significance of this thesis.In Chapter II,the functionalized biomacromolecules with good biocompatibility were used as gel factors and crosslinking agents to construct smart hydrogel networks with multiple dynamic linkages,such as dynamic imine bonds,hydrogen bonds,and?-? interactions.The hydrogels possessed the interconnected porous structures,rapid gelation time,excellent self-healing,good injectable characteristics,and superior tissue adhesiveness,which can be accurately injected into the wound site to avoid secondary damage caused by extrusion or deformation of surrounding tissues.The hemostasis time was strikingly shorter than 10 s after treating with hydrogels,making them promising candidates for long-lived wound dressings in critical situations.In Chapter III,the intriguing conductive hydrogels with multi-functionalities were fabricated by using functionalized biomacromolecules via in-situ polymerization.Owing to the delicate combination of physical and chemical cross-linking,such as covalent linkages,metal coordination interactions,hydrogen bonds,and ?-?interactions,the hydrogels possessed synergistic features of high stretchability(800%),thermoplasticity,self-healing,self-adhesiveness,and strain sensitivity.Considering above desirable multifunctionality,the hydrogels were assembled into capacitive strain sensors,which could distinctly perceive complex body motions from tiny physiological signal(breathing)to large movements(knee bending)as human motion detecting devices.Moreover,the hydrogels could also be applied for circuit repairing,programming and switches constructing,which paved a new way to explore the eco-friendly and high-performance flexible electronics.In Chapter IV,a binary-solvent organohydrogels with fast-response photochromism and thermotropic performances(10 s),distinct anti-freezing(-30?)and drying-resistant(for a month)performances were fabricated via facile in-situ polymerization and one-pot solvent displacement.Owing to the excellent environmental stability and color-change in response to external stimuli(light or heat),the organohydrogels could serve as long-life rewritable devices for data storage accompanied by high sensitivity and resolution.In addition,the organohydrogels served as passively smart windows integrating solar energy regulation(?Tsol=46.02%),ultraviolet protection and indoor temperature regulation,greatly expanding the practical application scope of smart display and optical devices.In Chapter V,the charged organohydrogels with amphiphilic hetero-networks are fabricated by facile emulsion polymerization.The synergistic collaboration of covalent linkages,electrostatic interactions,and hydrogen bonds endowed the organohydrogels with excellent stretchability,compressibility,and recoverability.The amphiphilic hetero-networks could experience structure rearrangement in response to the surrounding solvents(water or hexadecane),leading to the non-swelling behavior and switchable surface wettability.The wet adhesion driven by synergetic interactions,including hydrophobic effect,electrostatic interaction and non-swelling behavior,allowed the organohydrogels to be applied underwater.Owing to the elastic surfaces incorporated with zwitterionic groups and amphiphilic properties,the organohydrogels exhibited remarkable and broad-spectrum antifouling performances(Navicula sp.and D.tertiolecta as fouling models).Besides,the dynamic surface with switchable wettability endowed the organohydrogels with highly fouling removal efficiency(60%for D.tertiolecta and 77%for Navicula sp.).This study opened a new avenue for the development of the high-efficiency and durable fouling-resistance,which may achieve promising applications in eco-friendly marine antifouling. |
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