Effect of Polymer-based Grinding Aid on Sulfate Attacking Resistance of Concrete

Influences of polymer-based grinding aid（PGA） on the damage process of concrete exposed to sulfate attack under dry-wet cycles were investigated. The mass loss, dynamic modulus of elasticity（Erd）, and S and Ca element contents of concrete specimens were measured. Scanning electron microscopy（SEM）, mercury intrusion porosimetry（MIP）, and X-ray diffractometry（XRD） were used to investigate the changing of microstructure of interior concrete. The results indicated that PGA was capable of reducing the mass loss and improving the sulfate attack resistance of concrete. X-ray fluorescence（XRF） analysis revealed that PGA delayed the transport process of sulfate ions and Ca ions. In addition, MIP analysis disclosed that the micropores of concrete with PGA increased in the fraction of 20-100 nm and decreased in the residues of 200 nm. Compared with the blank sample, concrete with PGA had more slender and well-organized hydration products, and no changes in hydration products ratio or type were observed.

High-temperature polymer-based nanocomposites for high energy storage performance with robust cycling stability

High-power capacitors are highly demanded in advanced electronics and power systems,where rising concerns on the operating temperatures have evoked the attention on developing highly reliable high-temperature dielectric polymers.Herein,polyetherimide(PEI)filled with highly insulating Al_(2)O_(3)(AO)nanoparticles dielectric composite films have been fabricated aiming for high thermal stability and reliability operated under high cycling electric field and elevated temperature.At room temperature,incorporating a small fraction of 0.5 vol%AO nanoparticles gives rise to a highest discharged energy density(U_(e))of 5.57 J·cm^(-3)and efficiency(η)of 90.9%at650 MV·m^(-1),and a robust cycling stability up to 10^(7) cycles at 400 MV·m^(-1).Due to the substantially reduced dielectric loss,2.0 vol%AO/PEI nanocomposite film exhibits excellent high-temperature capacitive performances,delivering U_(e)~7.33 J·cm^(-3)withη~88.8%under 700 MV·m^(-1),and cycling stability up to 10^(6) cycles under 400 MV·m^(-1)at 100℃,and U_(e)~5.57 J·cm^(-3)withη~84.7%under 620 MV·m^(-1)at 150℃.Molecular dynamic simulations are performed to understand the microscopic mechanism via revealing the polymer relaxation process in the AO/PEI composite at elevated temperatures.Our results are therefore very encouraging for high-temperature high-power capacitor application.

Polymer-based EMI shielding composites with 3D conductive networks:A mini-review

High-frequency electromagnetic waves and electronic products can bring great convenience to people’s life,but lead to a series of electromagnetic interference(EMI)problems,such as great potential dangers to the normal operation of elec-tronic components and human safety.Therefore,the research of EMI shield-ing materials has attracted extensive attention by the scholars.Among them,polymer-based EMI shielding materials with light weight,high specific strength,and stable properties have become the current mainstream.The construction of 3D conductive networks has proved to be an effective method for the prepara-tion of polymer-based EMI shielding materials with excellent shielding effective-ness(SE).In this paper,the shielding mechanism of polymer-based EMI shield-ing materials with 3D conductive networks is briefly introduced,with emphasis on the preparation methods and latest research progress of polymer-based EMI shielding materials with different 3D conductive networks.The key scientific and technical problems to be solved in the field of polymer-based EMI shielding materials are also put forward.Finally,the development trend and application prospects of polymer-based EMI shielding materials are prospected.

Opportunities and challenges for the development of polymer-based biomaterials and medical devices

Biomaterials and medical devices are broadly used in the diagnosis,treatment,repair,replacement or enhancing functions of human tissues or organs.Although the living conditions of human beings have been steadily improved in most parts of the world,the incidence of major human’s diseases is still rapidly growing mainly because of the growth and aging of population.The compound annual growth rate of biomaterials and medical devices is projected to maintain around 10%in the next 10 years;and the global market sale of biomaterials and medical devices is estimated to reach$400 billion in 2020.In particular,the annual consumption of polymeric biomaterials is tremendous,more than 8000 kilotons.The compound annual growth rate of polymeric biomaterials and medical devices will be up to 15-30%.As a result,it is critical to address some widespread concerns that are associated with the biosafety of the polymer-based biomaterials and medical devices.Our group has been actively worked in this direction for the past two decades.In this review,some key research results will be highlighted.

Natural polymer-based adhesive hydrogel for biomedical applications

Hydrogel is a polymer network system that can form a hydrophilic three-dimensional network structure through different cross-linking methods.In recent years,hydrogels have received considerable attention due to their good biocompatibility and biodegradability by introducing different cross-linking mechanisms and functional components.Compared with synthetic hydrogels,natural polymer-based hydrogels have low biotoxicity,high cell affinity,and great potential for biomedical fields;however,their mechanical properties and tissue adhesion capabilities have been unable to meet clinical requirements.In recent years,many efforts have been made to solve these issues.In this review,the recent progress in the field of natural polymer-based adhesive hydrogels is highlighted.The authors first introduce the general design principles for the natural polymer-based adhesive hydrogels being used as excellent tissue adhesives and the challenges associated with their design.Next,their usages in biomedical applications are summarised,such as wound healing,haemostasis,nerve repair,bone tissue repair,cartilage tissue repair,electronic devices,and other tissue repairs.Finally,the potential challenges of natural polymer-based adhesive hydrogels are presented.

Solid-state electrolytes for solid-state lithium-sulfur batteries:Comparisons,advances and prospects

Compared with other secondary batteries,lithium-sulfur batteries(LSBs)have unparalleled advantages such as high energy density,low cost,etc.In liquid LSB systems,it is extremely easy to cause severe‘‘shuttle effecto and safety issues.Hence,the development of solid-state LSBs(SSLSBs)has been attracting much more attention.As the most essential part of the SSLSBs,the solid-state electrolyte(SSE)has received significant attention from researchers.In this review,we concentrate on discussing the core of SSLSBs,which is the SSE.Moreover,we also highlight the differences in the properties of the different SSEs,which are polymer-based electrolytes and ceramic-based electrolytes.In addition,the challenges and advances in different types of SSEs are also compared and described systematically.Furthermore,the prospects for new SSE systems and the design of effective SSE structures to achieve highperformance SSLSBs are also discussed.Thus,this review is expected to give readers a comprehensive and systematic understanding of SSEs for SSLSBs.

Small interfering RNAs based therapies for intracerebral hemorrhage: challenges and progress in drug delivery systems

Intracerebral hemorrhage(ICH)is a subtype of stroke associated with higher rates of mortality.Currently,no effective drug treatment is available for ICH.The molecular pathways following ICH are complicated and diverse.Nucleic acid therapeutics such as gene knockdown by small interfering RNAs(siRNAs)have been developed in recent years to modulate ICH’s destructive pathways and mitigate its outcomes.However,siRNAs delivery to the central nervous system is challenging and faces many roadblocks.Existing barriers to systemic delivery of siRNA limit the use of naked siRNA;therefore,siRNA-vectors developed to protect and deliver these therapies into the specific-target areas of the brain,or cell types seem quite promising.Efficient delivery of siRNA via nanoparticles emerged as a viable and effective alternative therapeutic tool for central nervous system-related diseases.This review discusses the obstacles to siRNA delivery,including the advantages and disadvantages of viral and nonviral vectors.Additionally,we provide a comprehensive overview of recent progress in nanotherapeutics areas,primarily focusing on the delivery system of siRNA for ICH treatment.

Flavonoids Loaded in Nanocarriers: An Opportunity to Increase Oral Bioavailability and Bioefficacy

Flavonoids are among the biggest group of polyphenols, widely distributed in plant-based foods. A plethora of evidence supports the health benefits and value of flavonoids can play in the physiological function treatment and in the prevention of disease particularly in the prevention of degenerative conditions including cancers, cardiovascular and neurodegenerative diseases. Hence, flavonoids represent the active constituents of many dietary supplements and herbal remedies, as well as there is an increasing interest in this class of polyphenols as functional ingredients of beverages, food grains and dairy products. Conversely, various studies have also shown that flavonoids have some drawbacks after oral administration such as stability, bioavailability and bioefficacy. This article reviews the current status of novel nanodelivery systems including nanospheres, nanocaspsules, micro- and nanoemulsions, micelles, solid lipid nanoparticles and nanostructured lipid capsules, successfully developed for overcoming the delivery challenges of flavonoids.

Electrochemical Properties of Polypyrrole-Coated Microelectrode Array and the Fabrication of Polypyrrole-Based Microelectronic Devices

Conducting polymers have been studied extensively. An interesting property of the conducting polymer is that the conductivity of some polymers, such as polypyrrolc, polyaniline, poly(3-methylthiophene) etc. , is affected by the voltage applied to them. For polypyrrole, the oxidized state is an electronic conductor and the reduced state is essentially insulating. Using this property, one can fabricate the polymer-based electronic devices. Experimental results of Pickun

Engineering Dual Oxygen Simultaneously Modified Boron Nitride for Boosting Adsorptive Desulfurization of Fuel

Oxygen atoms usually co-exist in the lattice of hexagonal boron nitride(h-BN). The understanding of interactions between the oxygen atoms and the adsorbate, however, is still ambiguous on improving adsorptive desulfurization performance. Herein, simultaneously oxygen atom-scale interior substitution and edge hydroxylation in BN structure were constructed via a polymer-based synthetic strategy.Experimental results indicated that the dual oxygen modified BN(BN–2O) exhibited an impressively increased adsorptive capacity about 12% higher than that of the edge hydroxylated BN(BN–OH) fabricated via a traditional method. The dibenzothiophene(DBT) was investigated to undergo multimolecular layer type coverage on the BN–2O uneven surface via π–π interaction, which was enhanced by the increased oxygen doping at the edges of BN–2O. The density functional theory calculations also unveiled that the oxygen atoms confined in BN interior structure could polarize the adsorbate, thereby resulting in a dipole interaction between the adsorbate and BN–2O. This effect endowed BN–2O with the ability to selectively adsorb DBT from the aromatic-rich fuel, thereafter leading to an impressive prospect for the adsorptive desulfurization performance of the fuel. The adsorptive result was in good accordance with Freundlich and pseudo-second-order adsorption kinetics model results. Therefore, the designing of a polymer-based strategy could be also extended to other heteroatom doping systems to enhance adsorptive performance.

Investigation of Thermal Characterization of a Thermally Enhanced FC-PBGA Assembly

In this paper, three-dimensional finite element analysis using the commercial ANSYS software is performed to study the thermal performance of a thermally enhanced FC-PBGA (flip-chip plastic ball grid array) assembly in both natural and forced convection environments. The thermally enhanced FC-PBGA assembly is a basic FC-PBGA assembly with a lid attached on top, after which an extruded-fin heatsink is attached on the top of the lid. The finite element model is complete enough to include key elements such as bumps, solder balls, substrate, printed circuit board, extruded-fin heatsink, lid, vias, TIM1 (thermal interface material 1), TIM2 (thermal interface material 2), lid-substrate adhesive and ground planes for both signal and power. Temperature fields are simulated and presented for several package configurations. Thermal resistance is calculated to characterize and compare the thermal performance by considering alternative design parameters of the polymer-based materials and the thermal enhancement components. The polymer-based materials include underfill, TIM1, TIM2, lid-substrate adhesive and substrate core material. The specific thermal enhancement components are the extruded-fin heatsink and the lid.

Microwave absorption properties of Ag naowires/carbon black composites

The composite that can absorb the high-performance electromagnetic（EM） wave is constructed into a sandwiched structure composed of carbon black（CB）/ethylene-vinyl acetate（EVA） and Ag naowires（Ag NWs）. The Ag NWs sandwiched between two CB/EVA layers are used to improve the absorption properties of composite. The effects of EVA-to-CB weight ratio, concentration and diameter of Ag NWs with a thickness of 0.4 mm on microwave absorption are investigated.The results indicate that for an EVA-to-CB weight ratio of 1：3, Ag NW concentration of 1.0 mg/100 m L, and average diameter of 56 nm, the reflection loss（RL） of the composite is below-10 d B in a frequency range of 9.3 Ghz–18.0 GHz, with the minimum values of-40.0 d B and-25.6 d B at 13.5 GHz and 15.3 GHz, respectively. A finite element method（FEM）is used for calculating the RL of the composite. The calculated results are in agreement with the experimental data.

Study on polyurethane-based porous materials and their adsorption properties

The flexible superhydrophobic thermoplastic polyurethane(TPU)porous material was prepared by heat-induced phase separation method with two cooling steps.The influence of the preparation process on the microstructure of the material was discussed in depth.The microstructure,hydrophobicity and specific surface area of porous TPU materials were analyzed in detail.The surface wettability,separation selectivity,saturated adsorption capacity and adsorption rate,mechanical properties,environmental adaptability and cyclic properties of porous TPU materials were studied.The results show that the TPU-8%porous monolithic material prepared by heat-induced phase separation method shows good performance when the polymer concentration is 8%,the phase separation temperature is 0℃,the phase separation time is 30min,and the mixing solvent ratio is 9:1.

Recent progress on multifunctional electromagnetic interference shielding polymer composites

The explosive development of electronic devices and wireless communication technology gives rise to the issue of electromagnetic pollution,known as electromagnetic interference(EMI).The accumulation of undesirable electromagnetic radiation in space disturbs the normal function of unshielded electronic appliances and poses seriously threat to human health.Thus,the development of EMI shielding materials have emerged to solve the grim problem.Considering the complex application contexts,EMI shielding materials have evolved from traditional single-function to multi-functions to meet the ever-increasing application requirements in recent few years.This paper provides detailed insight into the current re-search status and future challenges in the advancement of polymer-based EMI shielding materials with various functions.First,the basic theory of EMI shielding,factors influencing results and the dominating characterization technologies for EMI shielding properties are summarized.Then,the comprehensive descriptions of the seven types of multifunctional EMI shields are provided with respect to their structures,fabrication methods and specific functions.Meanwhile,the corresponding critical scientific and technical issues are proposed.Based on our comprehensive analysis,the main challenges in the development of multifunctional EMI shielding materials are presented.This review aims to provide some guidance and inspire more efforts toward functional EMI shielding material research to satisfy the growing requirements for next-generation electronic systems.

Review of recent advances of polymer based dielectrics for high-energy storage in electronic power devices from the perspective of target applications

Polymer-based dielectric capacitors are widely-used energy storage devices.However,although the functions of dielectrics in applications like high-voltage direct current transmission projects,distributed energy systems,high-power pulse systems and new energy electric vehicles are similar,their requirements can be quite different.Low electric loss is a critical prerequisite for capacitors for electric grids,while high-temperature stability is an essential pre-requirement for those in electric vehicles.This paper reviews recent advances in this area,and categorizes dielectrics in terms of their foremost properties related to their target applications.Requirements for polymer-based dielectrics in various power electronic equipment are emphasized,including high energy storage density,low dissipation,high working temperature and fast-response time.This paper considers innovations including chemical structure modification,composite fabrication and structure re-design,and the enhancements to material performances achieved.The advantages and limitations of these methods are also discussed.

Tunable patterning of microscale particles using a surface acoustic wave device with slanted-finger interdigital transducers

Polymer-based materials with patterned functional particles have been used to develop smart devices with multiple functionalities.This paper presents a novel method to pattern microscale particles into biocompatible polyethylene glycol diacrylate(PEGDA)fluid through a designed surface acoustic wave(SAW)device with slanted-finger interdigital transducers(SFITs).By applying signals of different frequencies,the SFITs can excite SAWs with various wavelengths to pattern the microscale particles.The structural design and working principle of the SAW device with SFITs are firstly presented.To investigate the generation of standing SAWs and pressure field distributions of the SAW device with SFITs,a numerical model was developed.Simulation results showed that different strip-shape patterned pressure fields can be generated,and the period and width of adjacent strips can be adjusted by changing the frequencies of the excitation signals.Experiments were performed to verify that the microscale particles in the PEGDA solution can be successfully patterned into strip-shape patterns with various positions,periods,and widths.The results obtained in this study demonstrate that the developed method of using an SAW device with SFITs can be used for tunable patterning of microscale particles in solutions,and shows great potential for biomedical and microfluidic applications.

Biomaterials for Adhesion in Orthopedic Applications:A Review

Adhesive biomaterials,historically,have had a wide range of applications in all medical fields.With the extensive variety of biomaterials with adhesion properties,the field of orthopedics benefits from using adhesives which can provide superior biocompatibility,resorbability,and low immunogenicity.The goal of this review is to serve as a reference of the types of adhesive biomaterials used clinically and their specific applicability in the field of orthopedics.The applications of adhesive biomaterials in orthopedics are as scaffolds,filler materials to treat bone defects and as carrier materials to deposit other bioactive materials to a site.First,we review the history and background of adhesive biomaterials and some of their general applications in orthopedics.Then we focus on the various types of adhesive biomaterials which include fibrin,collagen,polyurethane,epoxy resin,cyanoacrylates,polyesters and polymethylmethacrylate,all of which are excellent candidates for the field of orthopedics.We discuss their properties,current applications in all fields,and advantages and disadvantages found in some studies.Lastly,we indicate some future directions for adhesive biomaterials in orthopedics and highlight their advantages over conventional biomaterials in orthopedics.

Adsorptive carbon-based materials for biomedical applications

Adsorption or enrichment has been an indispensable and important measure in biomedical engineering since it is promising in diagnosis and treatment of complex diseases.The ongoing development in this arena starves for exploration of outstanding adsorptive materials.As an excellent candidate for adsorption or enrichment carriers,carbon-based material has demonstrated unique superiority in biomedical arena owing to its integrated charac-teristics.Herein,we review the lasted advance in adsorptive carbon-based materials for biomedical application with emphasis on carbon nanotubes(CNTs)-based,graphene-based,and biomass/polymer-based ones.We begin with the classification of different carbon-based materials and elaborate the respective preparation approaches that are utilized to realize optimized microstructure and physicochemical property.Afterwards,we introduce the different applications of carbon-based materials in biomedical arena,including blood purification,enrichment of glycopeptide and phosphopeptide,and breath analysis.Finally,we present a concise summary and give an outlook of this arena.