| Flexible sensors have the ability to detect changes in environmental stimulus signals such as stress,strain,and liquid,and have broad application prospects in fields such as human-computer interaction,health monitoring,and smart device.As the flexible sensor material,it needs to meet excellent mechanical properties,high linear sensitivity to stress and strain,wide strain and stress detection range,and maintain high conductivity,good stability,repeatability under large strains and other functions.However,the traditional flexible conductive materials generally cannot integrate the multiple properties,which is a huge challenge for the field of flexible sensors at present.However,ion conductive hydrogels have obvious advantages in the application of flexible sensors due to their flexibility,high-strain,and highly transparency.However,current ion conductive hydrogels still have problems such as low mechanical properties and electrical conductivity,unsatisfactory or non-linear sensitivity,and lack of multifunctional design.In response to these problems,this thesis constructs a series of new ion conductive hydrogels based onβ-cyclodextrin（β-CD）and its derivatives,and systematically studied its microstructure,basic performance,multifunctional characteristics,and the sensing performance and application potential of the hydrogel as a flexible sensor.（1）PVA/β-CD/PAA multifunctional ionic conductive hydrogel was prepared by a full-physical method using the chains PVA as main skeleton,PAA short chains,β-CD as the physical crosslinking agent and potassium chloride（KCl）.Due to the synergistic effect of multiple hydrogen bonds,the hydrogel showed great transparency（89%）,high strength（1.73 MPa）and compressive strength（22.27 MPa）,good stretchability（630%）and ionic conductivity(up to3.03 S m-1).β-CD as a physical crosslinking agent,could also improve the transparency of the hydrogel.In addition,the introduction of PAA chains not only enhanced the mechanical strength of the hydrogels,but also made the hydrogels have obvious responsiveness to pH,organic solvents,pressure and strain.The hydrogel has great application value as a multifunctional sensing material.（2）PAM/O-β-CD/Gel transparent ionic conductive hydrogels were produced through a one-pot thermal polymerization using acrylamide（AM）,gelatin（Gel）,oxidizedβ-CD（O-β-CD）and sodium chloride（Na Cl）.Due to the dynamic synergy of chemical and physical bonds,the hydrogel has great light transmittance（up to 89%）,the O-β-CD crosslinking agent can generate covalent bond and non-covalent bond simultaneously.In addition,the introduction of Na Cl could also improve the ionic conductivity of the hydrogel.Therefore,the hydrogels showed ultra-high strain/pressure sensitivity and stable repeatability when they were used as the flexible sensors,which have accurate detection and recognition ability in the application of detecting the human motions.（3）On the basis of Chapter 3,the hydrogel was endowed with anti-freezing and anti-drying properties,making the hydrogel suitable for complex environments and broadening the scope of application.PAM/O-β-CD/Gel/Gly transparent ionic conductive hydrogels were prepared by one-step method with AM,Gel,O-β-CD and Na Cl dissolved in glycerin-water solution.The structure of dynamic crosslinking network made the ionic conductive hydrogel sensor have the ultra-stretchability（>3800%）.The glycerin-water system also makes the hydrogel with the abilities of anti-freezing（-40℃）and anti-dryness（50℃）.In addition,the hydrogel also has high strain/pressure and temperature sensitivity(GF=1.10 and 0.263 k Pa-1 even at-20℃),large work range（0～1400%even at-40℃）,and stable repeatability.Thus,the hydrogel can be used as a flexible wearable sensor to detect human movements including joint,wrist,and finger bending,and even a series of subtle physiological activities such as swallowing and speaking.Besides,the hydrogel can also be used as the antipyretic paste repeatedly.Therefore,the hydrogel has great potential in the field of health monitoring and medical equipment. |
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