The recent research advances of wearable electronic strain sensors and applications,including signal transduction mechanisms,general materials,manufacture processes and potential applications was focused.Piezoresistivity,piezoelectricity and capacitance were three common signal transduction mechanism,moreover,triboelectric and optical effect mechanism were promised.Common materials used in flexible wearable electronic sensors,such as carbon materials,metal materials,inorganic semiconductors materials and functional composite materials were also introduced.The flexible wearable electronic sensors also had the practical and potential applications,which focused on health monitoring,motion monitoring,family rehabilitation,human-machine interfaces and soft robotics techniques.Finally,the challenges and future development of flexible wearable electronic strain sensors were presented.

With the rapid development of intelligent products,flexible sensors play an important role in the wearable electronics.This review focused on recent research advances of stretchable strain sensors and applications,including sensor types and transduction mechanisms,general materials,manufacture processes and potential applications.Common materials used in stretchable strain sensors,such as carbon materials,metal nanomaterials,mixed micro/nanomaterials,were also introduced.stretchable strain sensors also had the practical and potential applications,which focused on personal health monitoring,human motion detection,human-machine interfaces,rehabilitation and entertainment techniques.Finally,the challenges and future development of stretchable strain sensors were presented.

The inorganic fluorescent material is mainly composed of a matrix and an activator,and has the characteristics of strong absorption capacity,high conversion rate,stable physical and chemical properties.The luminescent principle and preparation methods of inorganic fluorescent materials were reviewed.The preparation methods included the high temperature solid phase reaction method,sol-gel method,chemical cooperation method,hydrothermal synthesis method and the microwave radiation method,and the advantage and disadvantage of each method were discussed.The future research direction of the inorganic fluorescent materials were discussed.

The research and development of new low-frequency absorbing materials has become an important aspect of penetration of multi-band radar.The factors affecting the absorbing properties of materials were discussed in detail.In view of the requirements of electromagnetic parameters of low-frequency absorbing materials,the current research and application of low-frequency absorbing materials were summarized,including ferrite materials and magnetic metal powder materials,and the effects of various micro-morphologies on low-frequency absorbing properties.The development of further expansion of low-frequency absorbing bands was prospected.

Research status and applications of phenolic resin-based prepregs at home and abroad were summarized.The preparation process of prepregs included solution impregnation and hot-melt impregnation.Phenolic resin-based prepregs were widely used in aerospace,transportation,electronic machinery and so on.

Phase change materials as an energy storage medium can effectively improve the utilization rate of non-renewable energy sources such as solar energy and industrial waste heat.It has become a research focus in the energy field at home and abroad,and the packaging technology of phase-change materials directly affects its energy storage performance and durability.Three main packaging technologies of solid-liquid phase change materials,including porous carrier composite method,microcapsule coating method and composite spinning method,were introduced from the aspects of basic principle and preparation technology,which provided suggestions for the packaging finalization of phase change materials.

Super absorbent polymer can absorb a large amount of external moisture,its water absorption can reach several hundred times or even thousands of times than its own mass,making it has important application value in the fields of sanitary products,water conservation of agriculture and forestry,medical treatment,etc.The main research achievements,process development progress,new technology product scale and major producers of super absorbent resins in recent years are introduced,and the future research and development as well as improvement directions are also prospected.

Silver nanowires have received more and more attention from the researchers due to the fact that silver nanowires present different characteristics comparing with macroscopic silver or single silver atoms (such as small size effect,interface effect,quanta dimension effect,macroscopical quanta tunnel effect and dielectric confinement effect).The characteristics of four common preparing methods of silver nanowires including polyol method,solvothermal method,ultraviolet irradiation method and template method and the application progress of silver nanowires which were employed in catalysts,electrics,optics and sensors,were reviewed.Neat silver nanowires were prepared by the template method.The ultraviolet irradiation method was employed to prepare noble metal nanostructure.The solvothermal method and polyol method were employed to fabricate silver nanowires at large scale.However,the cost of production with solvothermal method was increased due to the condition of high temperature and high pressure environment.On the contrary,the polyol method had better application prospect due to simple preparation technology,low cost and high efficiency.For its excellent electrical conductivity and optical property,silver nanowires were comprehensively used in liquid crystal display (LCD),wearable electronic devices,solar cell and so on.Moreover silver nanowires were widely applied to the biosensor and the catalytical electrode due to its biocompatibility,antibacterial property and large specific surface area.

The application of silane coupling agent is very extensive.The structure and mechanism of silane coupling agent were reviewed.The research progress of silane coupling agent at present stage and its application in polymer modification were introduced.Finally,the future development direction of silane coupling agent was prospected.

Graphene quantum dots (GQDs) are a new type of zero-dimensional carbon nanomaterial,which are different from the conventional carbon materials.Because of the quantum confinement and edge effects,it shows important application values in the chemical industry fields of catalysis,detection,biomedicine and sensors.Therefore,the preparation and application of GQDs has rapidly become one of the hot topics in the field of graphene research.The development of preparation and application of GQDs was reviewed.The problems that need to be solved and the future development trend and prospects were discussed.

Hollow mesoporous silica microspheres(HMSMs),possessing remarkable structural characteristics such as large pore volume,controlled outer mesoporous structure,high specific surface area,good biocompatibility and so on,are widely used in many fields,such as drug storage and release,nano-reactor,catalysis,adsorption,etc.A variety of methods have been reported to prepare successfully HMSMs.Various preparation methods of HMSMs were reviewed,including template method,selective etching method and spray drying method.Meanwhile,the advantages and limitations of these methods were discussed,and the application prospect of HMSMs was also prospected.

Recent research and development of biodegradable polyurethane were introduced.According to the structure of raw material,the type,the method to improve degradability as well as degradation mechanism of biodegradable polyurethane were expounded.Finally,the application field in medicine and fertilizer were illustrated in details,and the development of biodegradable polyurethane was expected.

Biodegradable plastics are a class of polymer materials that can be degraded by the action of natural microorganisms.Because of its good degradation,low production cost and good mechanical properties,it has become the hotpoint of current research.But there are still some shortcomings in the practical application,so domestic and foreign experts and scholars are studying its modified research.The types,synthesis,advantages and disadvantages of polymer biodegradable plastics were compared.Secondly,the practical application in recent years was analyzed,and the chemical and physical modification were compared.The problems of biodegradable plastic modification were analyzed,and its future development and application were summary and outlined.

The basic properties of polyether ether ketone (PEEK) were introduced,and analyzed the domestic and foreign enterprises producing PEEK and their products.At the same time,it was expounded the production and consumption of PEEK,and put forward the urgent problems and suggestion.

As a new energy storage system device between a battery and a conventional capacitor,supercapacitors greatly reduce the gap in terms of performance.The various electrode materials applicable to supercapacitors were summarized,classified the supercapacitors according to the differences in energy storage mechanisms,The latest research results of various types of supercapacitors were intruduced.It also illustrated the advantages and disadvantages of various types of supercapacitors.

Structural thermal insulation materials have attracted much attention because of their excellent thermal insulation,fire prevention and mechanical properties.The performance characteristics,preparation technology and application scope of four kinds of structural thermal insulation materials,including granular thermal insulation material,fibrous thermal insulation material,microporous thermal insulation material and layered thermal insulation material were introduced in detail.On this basis,the development trend of thermal insulation materials in the future was discussed.

With the rapid development of nanotechnology,nano-packaging materials have been extensively applied in the field of food packaging.The research progress of nanocomposite materials with high barrier property,antimicrobial property and preservation performance,and their application situation in food packaging were introduced.The biological security of nanocomposite packaging materials were also analyzed and evaluated.

Combined with the development of nonwovens in the medical field,four raw materials used inmedical nonwovens were selected.The research status of polypropylene,polylactic acid fiber,bio-based fibers and regenerated cellulose fibers were introduced from its own characteristics and advantages in medical applications.From the aspects of process characteristics and applications,four processing technologies of medical nonwovens,including spunbond,melt-blown,SMS composite and spunbonded spunlace composite,were expounded.Summarizing the new processing technology of foreign medical nonwovens was focused,including finishing process,electrospinning technology and other improved processes,introducing the new improvement process,the improved characteristic and the application in the future medical applications.Theoretical basis and technical support were provided for the selection and processing of medical nonwoven materials.

High-performance electrode materials are the key to advances in the areas of energy conversion and storage.The recent advances in the synthesis of transition metal carbides (TMC) and electrochemical applications in the field of new energy including hydrogen evolution reactions,oxygen redox reactions and dye-sensitized solar cells were summarized.The electrochemical properties and electrocatalytic reactions of TMC were related to their crystal structure,morphology and composition.Finally,the rational design of high performance TMC electrode was discussed,and the future research trend and prospect were forecasted.

ZIF-90 zeolitic imidazolate framework possesses large specific surface area,uniform pore structure,high hydrothermal stability and chemical stability,easy modification and facile preparation,which are widely used in separation,adsorption,catalysis,drug loading and other fields.The synthesis method and development status were briefly introduced.The challenges based on the special requirements existing in the current application fields were proposed.In addition,prospects in the synthesis and application of these composites were also discussed.

High-density aramid paper honeycomb is widely used in the aircraft cabin and cargo floor.The study on production process and mechanical properties has important significance.The micro-morphologies and mechanical properties of resin were performed to study the reasons for the mechanical properties difference for three specifications of high-density honeycombs.The advantages and disadvantages of aramid paper honeycomb,PMI foam and aluminum honeycomb as the core material of sandwich structure were compared.The results showed that both the mechanical properties and node resin form area of honeycomb were increased as the density increased.The mechanical properties of honeycomb were better than of PMI foam,Resistance to corrosion and local buckling of honeycomb were better than aluminum honeycomb.However,the problem was hard to control the process and easy to appear the phenomenon of uneven distribution of resin during manufacture.

As the new energy storage material with the best developing and applying prospect,lithium-ion battery not only has the advantages of safety,high efficiency and environmental friendliness,but also has the advantages of light weight,high working voltage,large energy density and long cycle life.Lithium-ion battery has become the focus in the research field of the new energy.The research progress in carbon-based cathode materials for lithium-ion batteries was reviewed.The synthesis and properties of carbon-based materials,silicon-based materials,tin-based materials and lithium metal were summarized.The recent research in the structural design and synthesis was put forward.

As one of the crucial components of electrode,binder can significantly affect the electrochemical performances of lithium-ion batteries.The rapid development of lithium-ion battery industry puts forward higher demands for the research of new advanced binder materials.Herein,the specific features,merits and demerits for different kinds of new advanced binders were discussed.Finally,the future development of advanced binders was prospected.

The sol-gel method has the advantages like mild reaction conditions,good crystallinity and high dispersion.When it was used with spin coating method or metal doping processes,the morphology and physicochemical properties of nanomaterials can be effectively improved,meanwhile the limitations of traditional methods can be overcome to make the nanomaterials can be further applied.The research current states and development trend of sol-gel method used in the synthesis of zero dimensional,one-dimensional,two-dimensional and three-dimensional nanomaterials were summarized.The synthesis methods of nanomaterials in recent years were introduced,expounded their interaction mechanism and superiority.The further development prospects were also discussed in the end.

The research progress of biodegradable film materials was reviewed from two aspects: the source of film materials and the degree of degradation of film materials.The biodegradable materials such as starch,polylactic acid (PLA) and polyvinyl alcohol (PVA) were mainly introduced.The future development of biodegradable film materials was expected.

Photo-degradation catalysts have many advantages in the application of degrading organic pollutants in air and water:low cost,high efficient,can be recycled and processed with no secondary pollution,etc.and show the application prospects in the strategy of sustainable development.A variety of new photodegradation catalysts and their applications were briefly described,and the problems that need to be solved in the future development of photodegradation catalysts were analyzed.It was pointed out that photo-degradation nano-composite catalysts had great potential to deal with actual pollution system.

Superfine fiber synthetic leather is the most ideal material to replace natural leather.Research progress of superfine fiber synthetic leather in recent years was introduced,including improving the sanitary and dyeing performances of synthetic leather composite,and the study of environmental impact.Finally development direction was prospected.

Metal-organic frameworks (MOFs) are a new kind of porous skeleton materials by self-assembly with metal ions and organic ligands.The composite materials composed by high porous,adjustable MOFs and other functional materials can play or go beyond their excellent characteristics.MOF composites as a new type of functional materials developed rapidly,and used in gas adsorption,separation and storage,catalysis,gas sensing,drug delivery,and even extended to the fuel cell,electric catalytic fields due to synergistic effect.The kinds of MOF composites were simply introduced.The materials were used to build composites including carbon-based materials,organic polymer materials,polyoxometallates,metal nanoparticles,metallic oxides,SiO₂ materials,quantum dots,bio-enzymes and so on.The applications of various MOF composites in gas adsorption and storage,heterogeneous catalysis and chemical sensors were analyzed.Finally,the application prospect of MOF was out looked,and functional,low-cost,easy to produce industrially MOF composites were the direction of efforts in future.

The selective contact between the hole transport material and the absorption layer plays an important role in improving the photoelectric conversion efficiency of perovskite cells.Different hole buffer layer materials have a direct impact on the growth of perovskite.Meanwhile,the hole buffer plays a decisive role in the stability and life of perovskite solar cells.The preparation method and application of NiO as hole transport layer material in perovskite solar cells were introduced.It was pointed out that the light transmittance and conductivity of NiO can be improved by optimizing the preparation method.And then the photoelectric conversion efficiency of perovskite solar cells can be improved.

Biomass is one of the renewable energy sources with promising prospects.Transforming biomass energy into clean hydrogen energy to replace fossil fuels is an inevitable trend in the development of hydrogen.Biomass hydrogen production method includes biomass thermochemical hydrogen production,biological hydrogen production and electrolytic biomass hydrogen method.The advantages and disadvantages of above methods were compared and reviewed.The liquid phase catalytic electrolytic biomass hydrogen production is a new hydrogen production technology.Compared with other hydrogen production methods,the reaction temperature is low,the energy consumption is low,and the purity of hydrogen is high,showing a very good development potential.

There are many effects for nanomaterials such as microsize effect,surface effect,quantum effect and macroscopic quantum tunneling effect,which make nanomaterials displaying many special characteristics.The research and development of functional Fe₃O₄/SiO₂ nanomaterials with magnetic property in biological field,and the prospect of its applications in biomedicine were discussed.

Asymmetric supercapacitor,that combines the benefits of the electric double layer capacitor and the faraday eagle capacitor,has been the focus in the field of supercapacitor in recent years due to its high energy density and power density,excellent cycle life and etc.The types of asymmetric supercapacitor electrode materials including carbon/transition metal oxide systems,carbon/conductive polymer systems and metal oxide/conductive polymer systems were introduced,the research progress of electrode materials was commented.

Olivine-structured lithium iron phosphate (LiFePO₄) is considered as one of the most promising anode materials for lithium-ion high power batteries due to its excellent performance.However,the low conductivity of the material itself restricts its large-scale commercial application.Coating conductive carbon materials on particles surface can effectively solve this problem.Some recent researches progress on surface modification of LiFePO₄ with different carbon-containing materials were summed,and explained the mechanisms of modification.Finally,an outlook for the research direction of LiFePO₄ anode materials was given.

TiO₂ was semiconductor and widely applied in the fields of catalysis,sensing,hydrogen generation,optics and optoelectronics,benefited from its many advantages such as chemical stability,green to environment and low toxicity,etc.However,On the one hand,TiO₂ only can be excited by UV,on the other hand,the rapid recombination of electron-hole (e^-—h⁺) pairs after excitation that leading to decrease of catalytic activity and quantum efficiency.The latest research progress on four main modification methods of TiO₂ including surface deposition of noble metal,semiconductor composite,ion doping and dye sensitization was introduced respectively.These all methods were aimed to make full use of the sunlight,or to induce crystal surface defects to restrain the recombination of electron-hole pairs.Finally,the modification of TiO₂ photocatalyst in the future was predicted.

Possessing outstanding mechanical properties and thermal stability,ultraviolet curing silicone resin,with the advantages of high curing efficiency,energy saving and environment friendly,possessing broad development prospects in coatings,3D printing materials and LED encapsulation materials.The resin has become a research hotspot in silicone industry in recent years.The recent research progress on the syntheses and applications of the silicone were mainly investigated.The prospective developments were also forecasted,indicating that the research key point was to solve the problem of curing density and oxygen inhibition,revealing that epoxy functionalized silicone became the focus of ultraviolet curing materials,and natural product functionalized ultraviolet curing silicone will also became a novel research direction.

It is an effective way to produce hydrogen using the modified TiO₂ by photocatalytic hydrolysis method.The mechanism of TiO₂ photocatalytic water-splitting for hydrogen production and several modification methods of TiO₂,such as:metal surface deposition,ion doping,compound semiconductor,light and so on were briefly showed.Finally,the prospect and challenge of photocatalyst for hydrogen evolution were discussed.

Inorganic solid electrolyte has great potential in lithium-ion battery industry,due to its high safety performance,high mechanical strength and other characteristics.NASICON inorganic lithium ion electrolyte has attracted much attention because of its advantages such as high conductivity,good stability and wide variety.The crystal structure,preparation process and doping modification of NASICON lithium ion electrolyte material were focus on.And the current research progress and future development of NASICON were reviewed.

Graphene,emerging as a two-dimensional single-layer carbon material,had been considered to be a promising class of adsorptive separation material for its high specific surface area and strong surface chemical activity.The preparation method of graphene,graphene oxide and composites,and its application in removal of heavy metal ions and organic pollutants were mainly summarized.Finally the future research direction of graphene and its composites was prospected.

Metal-organic frameworks (MOFs) is a porous material with high porosity,large specific surface area and uniformly dispersed active sites,and have been attracted attentions for researchers.The major research direction of bimetallic MOFs materials preparation and its application in gas storage and heterogeneous catalysis were reviewed.The adsorption mechanisms of CO₂ and the catalytic hydrogenation of phenol by doping metal active components were analyzed,and the prospect of its development was also given.

Hydrogel is a highly cross-linked water-swellable hydrophilic polymer network with good biocompatibility.It can be used as a drug carrier and functional scaffold,and has broad application prospects in the fields of tissue engineering,regenerative medicine and drug delivery.The preparation and self-healing mechanisms of self-healing hydrogels in recent years were mainly reviewed,such as:host-guest interaction,dynamic covalent and non-covalent interactions,metal-ligand interactions and hydrophobic interactions.The results of the application of drug carriers and biomimetic matrices in wound healing,filling complex tissue defects and inducing regeneration in tissue engineering and regenerative medicine were introduced,and expounded the current problems of self-healing hydrogels and their potential as drug delivery vehicles.The challenge was to look forward to its future clinical application prospects.