高强度离子导电凝胶研究进展

近年来,柔性可穿戴电子产品在人机交互、传感器等方面应用越来越广泛。离子导电凝胶具有高导电性、生物相容性、自愈合、良好的机械性能以及对可见光透明度高等特点,力学性能对离子导电凝胶的应用影响较大,通过添加纳米填料、无机盐和有机盐、聚电解质可以提升离子导电凝胶的力学性能。综述了纳米复合离子导电凝胶、盐离子导电凝胶、聚电解质离子导电凝胶的研究进展,对离子导电凝胶在传感器、柔性皮肤、生物医药等领域中的应用以及面临的困难和挑战进行了探讨,并展望了其未来发展方向。

细菌纤维素增强的低共熔溶剂导电离子凝胶及柔性传感器

针对目前导电离子凝胶传感材料力学性能不足的问题,以甜菜碱(Betaine)、衣康酸(IA)、丙烯酰胺(AM)和细菌纤维素(BC)为原料,开发了一种具有高拉伸强度的导电离子凝胶,并研究了该凝胶的机械力学和传感性能,探索了其在人体运动监测领域的实际应用.结果表明,由于引入BC,导电离子凝胶获得了较强的拉伸强度(689 kPa).同时,该导电离子凝胶可以在230 ms内监测200%范围内的拉伸变形,且具有很好的透明性,在2 mm厚度下,透射率可达87.64%.将该导电离子凝胶贴合在人体皮肤表面,可监测各种人体运动(如手指,手肘,手腕,膝盖等关节弯曲),在智能穿戴及医疗健康领域具有广阔的应用前景.

Preparation and Characterization of lonic Conductive Eutectogels Based on Polyacrylamide Copolymers with Long Hydrophobic Chain

With the blooming development of electronic technology,the use of electron conductive gel or ionic conductive gel in preparing flexible electronic devices is drawing more and more attention.Deep eutectic solvents are excellent substitutes for ionic liquids because of their good biocompatibility,low cost,and easy preparation,except for good conductivity.In this work,we synthesized a reactive quaternary ammonium monomer(3-acrylamidopropyl)octadecyldimethyl ammonium bromide with a hydrophobic chain of 18 carbons via the quaternization of 1-bromooctadecane and N-dimethylaminopropyl acrylamide at first,then we mixed quaternary ammonium with choline chloride,acrylic acid and glycerol to obtain a hydrophobic deep eutectic solvent,and initialized polymerization in UV light of 365 nm to obtain the ionic conductive eutectogel based on polyacrylamide copolymer with long hydrophobic chain.The obtained eutectogel exibits good stretchability(1200%),Young's modulus(0.185 MPa),toughness(4.2 MJ/m^(3)),conductivity(0.315 S/m).The eutectogel also shows desireable moisture resistance with the maximum water absorption of 11.7 wt%after one week at 25℃and 60%humidity,while the water absorption of eutectogel without hydrophobic long chains is 24.0 wt%.The introduction of long-chain hydrophobic groups not only improves the mechanical strength of the gels,but also significantly improves moisture resistance of the eutectogel.This work provides a simpler and more effective method for the preparation of ionic conductive eutectogels,which can further provide a reference for the applications of ionic conductive eutectogels in the field of flexible electronic devices.

Preparation of a Star Network PEG-based Gel Polymer Electrolyte and Its Application to Electrochromic Devices

A star network polymer with a pentaerythritol core linking four PEG-block polymeric arms was synthesized, and its corresponding gel polymer electrolyte based on lithium perchlorate and plasticizers EC/PC with the character being colorless and highly transparent has been also prepared. The polymer host was characterized and confirmed to be of a star network and an amorphous structure by FTIR, ^1H NMR and XRD studies. The polymer host hold good mechanical properties for pentaerythritol cross-linking. Maximum ionic conductivity of the prepared polymer electrolyte has reached 8.83 × 10 ^-4 S·cm^-1 at room temperature. Thermogravimetry （TG） of the polymer electrolyte showed that the thermal stability was up to at least 150 ℃. The gel polymer electrolyte was further evaluated in electrochromic devices fabricated by transparent PET-ITO and electrochromically active viologen derivative films, and its excellent performance promised the usage of the gel polymer electrolyte as ionic conductor material in electrochrornic devices.

Transparent,stretchable and anti-freezing hybrid double-network organohydrogels

Stretchable ionic conductors with high transparency and excellent resilience are highly desired for flexible electronics,but traditional ionic conductive hydrogels are easy to dry and freeze.Herein,a newly hybrid crosslinking strategy is presented for preparing a stretchable and transparent hydrogel by using sodium alginate(SA)and acrylamide based on the unique physically and covalently hybrid crosslinking mechanism,which is transformed into organohydrogel by simple solvent replacement.Due to the combination of hybrid crosslinking double network and hydrogen bond interactions introduced by the glycerin-water binary solvent,the SA-poly(acrylamide)-organohydrogel(SPOH)demonstrates excellent anti-freezing(-20℃)property,stability(>2 days),transparency,stretchability(~1600%)and high ionic conductivity(17.1 mS cm^(-1)).Thus,a triboelectric nanogenerator made from SPOH(O-TENG)shows an instantaneous peak power density of 262 mW m^(-2)at a load resistance of 10 MΩand efficiently harvests biomechanical energy to drive an electronic watch and light-emitting diode.Moreover,The O-TENG exhibits favorable long-term stability(2 weeks)and temperature tolerance(-20℃).In addition,the raw materials can be prepared into SPOH fibers by a simple tubular mold method,exhibiting high transparency,which can be used for laser transmission.The various abilities of the SPOH promise the application of energy harvesting and laser transmission for wearable electronics and biomedical field.

Facile preparation and high performance of wearable strain sensors based on ionically cross-linked composite hydrogels

Flexible sensors that can respond to multiple mechanical excitation modes and have high sensitivity are of great significance in the fields of electronic skin and health monitoring.Simulating multiple signal responses to skin such as strain and temperature remains an important challenge.Therefore,new multifunctional ion-crosslinked hydrogels with toughness and conductivity were designed and prepared in this work.A chemical gel with high mechanical strength was prepared by cross-linking acrylamide with N,N’-methylenebisacrylamide and ammonium persulfate.In addition,in order to enhance the conductive properties of the hydrogel,Ca^(2+),Mg^(2+)and Al^(3+)ions were added to the hydrogel during crosslinking.The double-layer network makes this ionic hydrogel show excellent mechanical properties.Moreover,the composite hydrogel containing Ca^(2+)can reach a maximum stretch of 1100%and exhibits ultra-high sensitivity(Sp=10.690 MPa^(-1)).The obtained hydrogels can successfully prepare wearable strain sensors,as well as track and monitor human motion.The present prepared multifunctional hydrogels are expected to be further expanded to intelligent health sensor materials.

In situ deposited multilayer integrated hydrogels for deformable and stretchable supercapacitors

Hydrogel systems promote the development of flexible energy storage devices because of their inherent mechanical elasticity and ionic conductivity.However,achieving stable energy storage capacity under violent mechanical deformation is still a challenge for hydrogel devices.In this work,an all-in-one integrated supercapacitor(AISC)was assembled using in situ deposited polyaniline/graphene oxide nanocomposites for both sides of the incorporated ionic hydrogel electrolyte.The assembly process of the AISC was greatly simplified,and the displacement and separation of the multilayer structured hydrogel complex were avoided during mechanical deformation.The hydrogel electrolyte with ionic additives exhibited strong adhesion and flexibility,and high ionic conductivity,thereby ensuring the excellent specific capacitance and rate performance of the AISC.The specific capacitances of the AISC were 222.8 mF cm^(−2) at the current density of 0.2 mA cm^(−2) and 151.7 mF cm^(−2) at 3.2 mA cm^(−2).The capacitance retention rate was 68.1%.The energy density of a piece of the device reached 44.6μW h cm^(−2) at a power density of 120.0μW cm^(−2).Moreover,reliable and reproducible energy storage was acquired under bending,compression,and stretching deformations.The AISC was also easily assembled in series to power a light-emitting diode(LED)light.This work provides a facile approach to the construction of flexible supercapacitors for the development of energy storage devices in flexible electronics.

Regenerated hydrogel electrolyte towards an all-gel supercapacitor

Electrolyte regeneration is an important goal for environmental protection and sustainable development efforts.Herein,we report a facile strategy inspired by the transformation of edible dough from flour to regenerate hydrogel electrolytes from their dehydrated copolymer granules(CGs)via direct addition of water or salt solution.With the aid of heating,this procedure is efficient,relatively quick,and easily implemented.The dehydrated CGs are lightweight,reusable and stable under long-term storage.Even after 5 cycles of dehydration and regeneration,the regeneration efficiency of the hydrogel electrolytes,as evaluated based on retention of mechanical strength,is over 60%.The regenerated electrolytes possess considerable ionic conductivity,reprocessability,and 3D-printability.Furthermore,an all-gel supercapacitor assembled from the regenerated hydrogel electrolyte and activated carbon electrode with CGs as binder demonstrates excellent interfacial compatibility.The assembled all-gel supercapacitor can maintain 98.7% of its original specific capacitance after 100 bending tests,and can operate in a wide temperature range spanning from-15 to 60°C.This work may provide a new access to the development of renewable materials for various applications in the fields of intelligent devices,wearable electronics and soft robotics.