Study On Controllable Deformation,flexible Electronics And Anti-fog Coatings Based On Tough Organohydrogels

Organisms in their natural environment adjust their physiological activities in order to adapt to complex and harsh environmental conditions,which inspired the development of biomimetic materials.In recent years,these biomimetic materials have garnered increasing attention in various fields.In order to meet the requirement of specific scenarios,biomimetic materials must feature flexibility,high stability,long working life,and strong mechanical properties.Among those materials,tough organohydrogels(OGHs)gaining increased attention due to their ultra-high mechanical toughness and stretchability.Furthermore,OHGs feature drying and freezing resistance.As OGHs can be employed in harsh environments they are considered ideal biomimetic materials.Therefore,this Thesis tackles the design,synthesis,modification and characterization of(ultra)tough(organo)hydrogels.As a model system a calcium alginate/polyacrylamide(PAAm)hydrogel was employed.The organohydrogel was prepared by solvent displacement(glycerin).By immersing or patterning(local treatment)the OHG with iron(III)aqueous solution(i.e.dapping on the surface with wet(iron(III)aqueous solution))the bulk or local mechanical properties of the OHG were altered.Interestingly,the thus prepared toughened OHGs show great resistance to drying and freezing.The OHGs maintained their flexibility upon long storage times and at a temperature of-50°C.The local toughening could be employed to code rigid and soft structures,which was exploited for conformal packaging of rigid electronic components for the generation of soft electronics.Here,the rigid parts of the gel serve to reduce the load(mechanical stress)relayed to the rigid electronic component upon application mechanical stresses,such as tensile and compressive strain,due to mitigating the mechanical mismatch between different components.The so-called island-bridge structure was employed for incorporating a rigid array of LEDs while as the soft conductor room temperature liquid metals(i.e Galinstan)are used.Very high mechanical durability was achieved,enough to withstand up to 1000%of tensile strain while it showed good long-term stability and thus,can be applied in challenging environmental conditions.Finally,the feasibility of the OHGs to serve as anti-fog film was explored.Here,a gelatin hydrogel was selected,which was converted into an OHG by the solvent displacement technique.The gelatin-based OHG could be coated by a sequential fabrication procedure on glass and other transparent substrates,yielding a transparent anti-fogging coating.The OHG can be employed in a temperature range between-70 ~oC to 100 ~oC while affording long-term and high fogging resistance.