FROM CRYSTALLINE BLOCK SLIPS TO DOMINANCE OF NETWORK STRETCHING——MECHANISMS OF TENSILE DEFORMATION IN SEMI-CRYSTALLINE POLYMERS

The mechanism of tensile deformation in semi-crystalline polymers was studied based on true stress-strain curvesobtained with the aid of a video-controlled tensile set-up. The deformation is affected by both the crystalline and theamorphous phases. However, the relative weights of the two portions change with the deformation stage. At lowdeformations the coupling and coarse slips of the crystalline blocks dominate the mechanical properties, which allows thesystem to maintain a homogeneous strain distribution in the sample. As the stretching increases, at a critical strain the forcegenerated from entangled fluid portions reaches a critical value to destroy the crystallites. The dominant deformationmechanism then changes into a disaggregation - recrystallization process.

A phase-field model for simulating various spherulite morphologies of semi-crystalline polymers

A modified phase-field model is proposed for simulating the isothermal crystallization of polymer melts. The model consists of a second-order phase-field equation and a heat conduction equation. It obtains its model parameters from the real material parameters and is easy to use with tolerable computational cost. Due to the use of a new free energy functional form, the model can reproduce various single crystal morphologies of polymer melts under quiescent conditions, including dendritic, lamellar branching, ring-banded, breakup of ring-banded, faceted hexagonal, and spherulitic structures. Simulation results of isotactic polystyrene crystals demonstrate that the present phase-field model has the ability to give qualitative predictions of polymer crystallization under isothermal and quiescent conditions.

Fundamental Mechanism of Slow Crack Growth in Semi-Crystalline Polymers under a Constant Load

The purpose is to quantitatively present in a single equation all the factors that affect the failure time by Slow Crack Growth (SCG) in a semi-crystalline polymer (SCP) under a constant load. The fundamental mechanism of fracture is displayed at the molecular level. The rate of fracturing is determined by the Eyring theory of thermal activation. The resulting equation includes the important molecular properties of therein, the length and density of the tie molecules. The underlying microfracture process is the unfolding of the chains in the crystal under the action of the tie molecules.

Thermophysical Characterization and Crystallization Kinetics of Semi-Crystalline Polymers

Final properties and behavior of polymer parts are known to be directly linked to the thermomechanical history experienced during their processing. Their quality depends on their structure, which is the result of the interactions between the process and the polymers in terms of thermomechanical kinetics. To study the actual behavior of a polymer during its transformation, it is necessary to take into account all the thermal dependencies of their thermophysical properties. In this paper, a complete experimental thermal characterization of a semi-crystalline polymer is performed. Thermal conductivity is measured using the hot wire method. The PVT diagram is obtained by means of an isobaric piston type dilatometer. Heat capacity is characterized versus temperature by differential scanning calorimetry (DSC). A modification of the Schneider rate crystallization equations is proposed, allowing to identify in a simple way all the crystallization kinetics parameters, using only DSC measurements. Finally, a multiphysical coupled model is built in order to numerically simulate the cooling of a polypropylene plate, as in the cooling stage of the injection molding process. Calculated evolutions of temperature, crystallinity, pressure and specific volume across the plate thickness are presented and commented.

Recent advances and innovations in the design and fabrication of wearable flexible biosensors and human health monitoring systems based on conjugated polymers

Wearable biosensors have received great interest as patient-friendly diagnostic technologies because of their high flexibility and conformability.The growing research and utilization of novel materials in designing wearable biosensors have accelerated the development of point-of-care sensing platforms and implantable biomedical devices in human health care.Among numerous potential materials,conjugated polymers(CPs)are emerging as ideal choices for constructing high-performance wearable biosensors because of their outstanding conductive and mechanical properties.Recently,CPs have been extensively incorporated into various wearable biosensors to monitor a range of target biomolecules.However,fabricating highly reliable CP-based wearable biosensors for practical applications remains a significant challenge,necessitating novel developmental strategies for enhancing the viability of such biosensors.Accordingly,this review aims to provide consolidated scientific evidence by summarizing and evaluating recent studies focused on designing and fabricating CP-based wearable biosensors,thereby facilitating future research.Emphasizing the superior properties and benefits of CPs,this review aims to clarify their potential applicability within this field.Furthermore,the fundamentals and main components of CP-based wearable biosensors and their sensing mechanisms are discussed in detail.The recent advancements in CP nanostructures and hybridizations for improved sensing performance,along with recent innovations in next-generation wearable biosensors are highlighted.CPbased wearable biosensors have been—and will continue to be—an ideal platform for developing effective and user-friendly diagnostic technologies for human health monitoring.

Synthetic polymers:A review of applications in drilling fluids

With the growth of deep drilling and the complexity of the well profile,the requirements for a more complete and efficient exploitation of productive formations increase,which increases the risk of various complications.Currently,reagents based on modified natural polymers(which are naturally occurring compounds)and synthetic polymers(SPs)which are polymeric compounds created industrially,are widely used to prevent emerging complications in the drilling process.However,compared to modified natural polymers,SPs form a family of high-molecular-weight compounds that are fully synthesized by undergoing chemical polymerization reactions.SPs provide substantial flexibility in their design.Moreover,their size and chemical composition can be adjusted to provide properties for nearly all the functional objectives of drilling fluids.They can be classified based on chemical ingredients,type of reaction,and their responses to heating.However,some of SPs,due to their structural characteristics,have a high cost,a poor temperature and salt resistance in drilling fluids,and degradation begins when the temperature reaches 130℃.These drawbacks prevent SP use in some medium and deep wells.Thus,this review addresses the historical development,the characteristics,manufacturing methods,classification,and the applications of SPs in drilling fluids.The contributions of SPs as additives to drilling fluids to enhance rheology,filtrate generation,carrying of cuttings,fluid lubricity,and clay/shale stability are explained in detail.The mechanisms,impacts,and advances achieved when SPs are added to drilling fluids are also described.The typical challenges encountered by SPs when deployed in drilling fluids and their advantages and drawbacks are also discussed.Economic issues also impact the applications of SPs in drilling fluids.Consequently,the cost of the most relevant SPs,and the monomers used in their synthesis,are assessed.Environmental impacts of SPs when deployed in drilling fluids,and their manufacturing processes are identified,together with advances in SP-treatment methods aimed at reducing those impacts.Recommendations for required future research addressing SP property and performance gaps are provided.

Lithium-Ion Charged Polymer Channels Flattening Lithium Metal Anode

The concentration difference in the near-surface region of lithium metal is the main cause of lithium dendrite growth.Resolving this issue will be key to achieving high-performance lithium metal batteries(LMBs).Herein,we construct a lithium nitrate(LiNO_(3))-implanted electroactiveβphase polyvinylidene fluoride-co-hexafluoropropylene(PVDF-HFP)crystalline polymorph layer(PHL).The electronegatively charged polymer chains attain lithium ions on the surface to form lithium-ion charged channels.These channels act as reservoirs to sustainably release Li ions to recompense the ionic flux of electrolytes,decreasing the growth of lithium dendrites.The stretched molecular channels can also accelerate the transport of Li ions.The combined effects enable a high Coulombic efficiency of 97.0%for 250 cycles in lithium(Li)||copper(Cu)cell and a stable symmetric plating/stripping behavior over 2000 h at 3 mA cm^(-2)with ultrahigh Li utilization of 50%.Furthermore,the full cell coupled with PHL-Cu@Li anode and Li Fe PO_(4) cathode exhibits long-term cycle stability with high-capacity retention of 95.9%after 900 cycles.Impressively,the full cell paired with LiNi_(0.87)Co_(0.1)Mn_(0.03)O_(2)maintains a discharge capacity of 170.0 mAh g^(-1)with a capacity retention of 84.3%after 100 cycles even under harsh condition of ultralow N/P ratio of 0.83.This facile strategy will widen the potential application of LiNO_(3)in ester-based electrolyte for practical high-voltage LMBs.

Polymer engineering for electrodes of aqueous zinc ion batteries

With the increasing demand for scalable and cost-effective electrochemical energy storage,aqueous zinc ion batteries(AZIBs)have a broad application prospect as an inexpensive,efficient,and naturally secure energy storage device.However,the limitations suffered by AZIBs,including volume expansion and active materials dissolution of the cathode,electrochemical corrosion,irreversible side reactions,zinc dendrites of the anode,have seriously decelerated the civilianization process of AZIBs.Currently,polymers have tremendous superiority for application in AZIBs attributed to their exceptional chemical stability,tunable structure,high energy density and outstanding mechanical properties.Considering the expanding applications of AZIBs and the superiority of polymers,this comprehensive paper meticulously reviews the benefits of utilizing polymeric applied to cathodes and anodes,respectively.To begin with,with adjustable structure as an entry point,the correlation between polymer structure and the function of energy storage as well as optimization is deeply investigated in respect to the mechanism.Then,depending on the diversity of properties and structures,the development of polymers in AZIBs is summarized,including conductive polymers,redox polymers as well as carbon composite polymers for cathode and polyvinylidene fluoride-,carbonyl-,amino-,nitrile-based polymers for anode,and a comprehensive evaluation of the shortcomings of these strategies is provided.Finally,an outlook highlights some of the challenges posed by the application of polymers and offers insights into the potential future direction of polymers in AZIBs.It is designed to provide a thorough reference for researchers and developers working on polymer for AZIBs.

Bifunctional TiO_(2-x)nanofibers enhanced gel polymer electrolyte for high performance lithium metal batteries

Exploration of advanced gel polymer electrolytes(GPEs)represents a viable strategy for mitigating dendritic lithium(Li)growth,which is crucial in ensuring the safe operation of high energy density Li metal batteries(LMBs).Despite this,the application of GPEs is still hindered by inadequate ionic conductivity,low Li^(+)transference number,and subpar physicochemical properties.Herein,Ti O_(2-x)nanofibers(NF)with oxygen vacancy defects were synthesized by a one-step process as inorganic fillers to enhance the thermal/mechanical/ionic-transportation performances of composite GPEs.Various characterizations and theoretical calculations reveal that the oxygen vacancies on the surface of Ti O_(2-x)NF accelerate the dissociation of Li PF_6,promote the rapid transfer of free Li^(+),and influence the formation of Li F-enriched solid electrolyte interphase.Consequently,the composite GPEs demonstrate enhanced ionic conductivity(1.90m S cm^(-1)at room temperature),higher lithium-ion transference number(0.70),wider electrochemical stability window(5.50 V),superior mechanical strength,excellent thermal stability(210℃),and improved compatibility with lithium,resulting in superior cycling stability and rate performance in both Li||Li,Li||Li Fe PO_(4),and Li||Li Ni_(0.8)Co_(0.1)Mn_(0.1)O_(2)cells.Overall,the synergistic influence of nanofiber morphology and enriched oxygen vacancy structure of fillers on electrochemical properties of composite GPEs is comprehensively investigated,thus,it is anticipated to shed new light on designing high-performance GPEs LMBs.

Ultraviolet‑Irradiated All‑Organic Nanocomposites with Polymer Dots for High‑Temperature Capacitive Energy Storage

Polymer dielectrics capable of operating efficiently at high electric fields and elevated temperatures are urgently demanded by next-generation electronics and electrical power systems.While inorganic fillers have been extensively utilized to improved high-temperature capacitive performance of dielectric polymers,the presence of thermodynamically incompatible organic and inorganic components may lead to concern about the long-term stability and also complicate film processing.Herein,zero-dimensional polymer dots with high electron affinity are introduced into photoactive allyl-containing poly(aryl ether sulfone)to form the all-organic polymer composites for hightemperature capacitive energy storage.Upon ultraviolet irradiation,the crosslinked polymer composites with polymer dots are efficient in suppressing electrical conduction at high electric fields and elevated temperatures,which significantly reduces the high-field energy loss of the composites at 200℃.Accordingly,the ultraviolet-irradiated composite film exhibits a discharged energy density of 4.2 J cm^(−3)at 200℃.Along with outstanding cyclic stability of capacitive performance at 200℃,this work provides a promising class of dielectric materials for robust high-performance all-organic dielectric nanocomposites.

New Kinetics Equation for Stress Relaxation of Semi-crystalline Polymers below Glass Transition Temperature

The stress relaxation of semi-crystalline nylon 1010 cannot be fitted by the Kohlrausch-Williams-Watts formula when the experiments were performed at pre-yielding regime below the glass transition temperature.We study this problem and identify the two-step mechanism of stress relaxation.At short time scale,relaxation is fast,dominated by stress biased thermal fluctuation with a fixed short-range length scale(activation volume).At long time scale,relaxation is slow due to the emergence of a cooperative long-range length scale determined by the stress fluctuation.The cooperative length scale is proportional to the reciprocal of stress and the amplitude of stress fluctuation is the product of stress and activation volume.Based on this two-step mechanism,we propose a new kinetics equation to capture the stress relaxation effectively,where the short time relaxation is described by an Eyring-like local activation and the long-time relaxation is captured by a cooperative excitation process resorting to an extension from the random first order transition theory.Our equation fits the experimental data well and can serve as a model to guide the related experiments of relaxation processes in crystalline solids.

Achieving Synergistic Improvement in Dielectric and Energy Storage Properties of All-Organic Poly(Methyl Methacrylate)-Based Copolymers Via Establishing Charge Traps

How to achieve synergistic improvement of permittivity(ε_(r))and breakdown strength(E_(b))is a huge challenge for polymer dielectrics.Here,for the first time,theπ-conjugated comonomer(MHT)can simultaneously promote theε_(r)and E_(b)of linear poly(methyl methacrylate)(PMMA)copolymers.The PMMA-based random copolymer films(P(MMA-co-MHT)),block copolymer films(PMMA-b-PMHT),and PMMA-based blend films were prepared to investigate the effects of sequential structure,phase separation structure,and modification method on dielectric and energy storage properties of PMMA-based dielectric films.As a result,the random copolymer P(MMA-coMHT)can achieve a maximumε_(r)of 5.8 at 1 kHz owing to the enhanced orientation polarization and electron polarization.Because electron injection and charge transfer are limited by the strong electrostatic attraction ofπ-conjugated benzophenanthrene group analyzed by the density functional theory(DFT),the discharge energy density value of P(MMA-co-PMHT)containing 1 mol%MHT units with the efficiency of 80%reaches15.00 J cm^(-3)at 872 MV m^(-1),which is 165%higher than that of pure PMMA.This study provides a simple and effective way to fabricate the high performance of polymer dielectrics via copolymerization with the monomer of P-type semi-conductive polymer.

Comprehension-driven design of advanced multi-block single-ion conducting polymer electrolytes for high-performance lithium-metal batteries

The continuously growing importance of batteries for powering(hybrid)electric vehicles and storing renewable energy has prompted a renewed focus on lithium-metal batteries(LMBs)in recent years,as its high theoretical specific capacity of about 3860 mA h g^(-1) and very low redox potential(-3.04 V vs.the standard hydrogen electrode)promise substantially higher energy densities compared to current lithium-ion batteries(LIBs)[1].However,lithium metal electrodes face severe challenges associated with the risk of dendritic lithium deposition and the high reactivity with traditional organic liquid electrolytes,resulting in a continuous loss of electrochemically active lithium and a relatively low Coulombic efficiency[2].To address these challenges,solid inorganic and polymer electrolytes have emerged as a potentially saferalternative.

Influence of Mass Ratio of Resin and Stabilizer on Mechanical Properties of Mo Fiber-reinforced Granite Polymer Composite

Because inferior mechanical strength of granite polymer composite(GPC)has become the main drawback limiting its application and popularization,Mo fibers were added into(GPC)to improve its mechanical strength.Mechanical properties of matrix materials with different mass ratio of resin and stabilizer(MRRS)were investigated systematically.The influences of MRRS on interface bonding strength of Mo fiber-matrix,wettability and mechanical strength of GPC were discussed,respectively,and the theoretical calculation result of MRRS k was obtained,with the optimal value of k=4.When k=4,tensile strength,tensile strain and fracture stress of the cured resin achieve the maximum values.But for k=7,the corresponding values reach the minimum.With the increase of MRRS k,surface free energy of the cured resin first increases and then decreases,while contact angles between Mo sample and matrix have displayed the opposite trend.Wettability of resin to Mo fiber is the best at k=4.Pulling load of Mo fiber and interface bonding strength appear the maximum at k=4,followed by k=5,k=3 the third,and k=7 the minimum.When k=4,mechanical properties of Mo fiber-reinforced GPC are optimal,which is consistent with the result of theoretical calculation.This study is of great significance to get better component formulas of Mo fiber reinforced GPC and to improve its application in machine tools.

Effect of electron-electron interaction on polarization process of exciton and biexciton in conjugated polymer

By using one-dimensional tight-binding model modified to include electron-electric field interaction and electron-electron interaction,we theoretically explore the polarization process of exciton and biexciton in cis-polyacetylene.The dynamical simulation is performed by adopting the non-adiabatic evolution approach.The results show that under the effect of moderate electric field,when the strength of electron-electron interaction is weak,the singlet exciton is stable but its polarization presents obvious oscillation.With the enhancement of interaction,it is dissociated into polaron pairs,the spin-flip of which can be observed through modulating the interaction strength.For the triplet exciton,the strong electron-electron interaction restrains its normal polarization,but it is still stable.In the case of biexciton,the strong electron-electron interaction not only dissociate it,but also flip its charge distribution.The yield of the possible states formed after the dissociation of exciton and biexciton is also calculated.

Voltage-modulated polymer nanopore field-effect transistor for multi-sized nanoparticle detection

Solid-state nanopores offer a range of distinct advantages over biological nanopores,such as structural diversity and greater stability and durability;this makes them highly promising for high-resolution nanoparticle sensing.Biological nanopores can exhibit gating characteristics with stress-responsive switches and can demonstrate specificity toward particular molecules.Drawing inspiration from biological nanopores,this paper introduces a novel polymer nanopore with field-effect characteristics,leveraging a conductive polymer in its construction to showcase intriguing gating behavior.Notably,in this device,the polymer layer serves as the gate,enabling precise control over the source–drain current response inside and outside the pore by simply adjusting the gate voltage.This unique feature allows fine-tuning of the nanopore’s sensitivity to nanoparticles of varying sizes and facilitates its operation in multiple modes.Experimental results reveal that the developed polymer nanopore field-effect transistor demonstrates remarkable selectivity in detecting nanoparticles of various sizes under different applied voltages.The proposed single device demonstrates the exceptional ability to detect multiple types of nanoparticle,showcasing its immense potential for a wide range of applications in biological-particle analysis and medical diagnostics.

Renewable Polymers in Biomedical Applications:From the Bench to the Market

Polymers from renewable resources have been used for a long time in biomedical applications and found an irreplaceable role in some of them.Their uses have been increasing because of their attractive properties,contributing to the improvement of life quality,mainly in drug release systems and in regenerative medicine.Formulations using natural polymer,nano and microscale particles preparation,composites,blends and chemical modification strategies have been used to improve their properties for clinical application.Although many studies have been carried out with these natural polymers,the way to reach the market is long and only very few of them become commercially available.Vegetable cellulose,bacterial cellulose,chitosan,poly(lactic acid)and starch can be found among the most studied polymers for biological applications,some with several derivatives already established in the market,and others with potential for such.In this scenario this work aims to describe the properties and potential of these renewable polymers for biomedical applications,the routes from the bench to the market,and the perspectives for future developments.

Erosion control of Chinese loess using polymer SH and ryegrass

The China Loess Plateau is subjected to severe soil erosion triggered by intense rainfall,resulting in significant harm and losses to both human society and the natural surroundings.In this study,a novel technique for managing loess erosion is introduced,which involves the utilization of a combined polymer SH and ryegrass.A comprehensive series of tests were undertaken,including rainfall erosion tests,disintegration experiments,and scanning electron microscopy examinations,to assess the accumulative sediment yield(ASY),disintegration ratio,and microstructural features of both untreated and treated loess samples.The results showed a significant reduction in ASY with increased dry density of untreated loess.Furthermore,the combined technique effectively controlled erosion,limiting ASY to 266.2 g/cm^(2)in 60 minutes.This was approximately one-sixth,one-ninth,and one-fifteenth of the ASY in SH-treated loess(L-SH),ryegrass-treated loess(L-R),and untreated loess,respectively.It resisted disintegration better than ryegrass alone but slightly less than SH.This improvement was due to the combined effect of SH and ryegrass,which reduced raindrop impact,improved loess microstructure,and boosted ryegrass growth.The innovative technique holds the potential to be applied as a field-scale technique in the Loess Plateau region of China.

Exploring innovative synthetic solutions for advanced polymer-based electrochromic energy storage devices:Phenoxazine as a promising chromophore

The current investigation offers an innovative synthetic solution regarding electrochromic(EC)and energy storage applications by exploring phenoxazine(POZ)moiety.Subsequently,three POZ-based polymers(polyimide,polyazomethine,and polyamide)were synthesized to ascertain the superior performer.The polyamide exhibited remarkable attributes,including high redox stability during 500 repetitive CVs,optical contrast of 61.98%,rapid response times of 1.02 and 1.38 s for coloring and bleaching,EC efficiency of 280 cm^(2)C^(-1).and decays of the optical density and EC efficiency of only 12.18%and 6.23%after 1000 cycles.Then,the energy storage performance of polyamide PA was tested,for which the following parameters were obtained:74.7 F g^(-1)(CV,scan rate of 10 mV s^(-1))and 118 F g^(-1)(GCD,charging current of 0.1 A g^(-1)).Then,the polyamide was tested in EES devices,which yielded the following EC parameters:an optical contrast of 62.15%,response times of 9.24 and 5.01 s for coloring and bleaching,EC efficiency of 178 cm^(2)C^(-1),and moderate decays of 20.25%and 23.24%for the optical density and EC efficiency after 500 cycles.The energy storage performance included a capacitance of 106 F g^(-1)(CV,scan rate of 0.1 mV s^(-1))and 9.23 F g^(-1)(GCD,charging current of 0.1 A g^(-1)),capacitance decay of 11.9%after500 cycles,and 1.7 V retention after 2 h.Also,two EES devices connected in series powered a 3 V LED for almost 30 s.

A Stable Open-Shell Conjugated Diradical Polymer with Ultra-High Photothermal Conversion Efficiency for NIR-Ⅱ Photo-Immunotherapy of Metastatic Tumor

Massive efforts have been concentrated on the advance of eminent near-infrared(NIR) photothermal materials(PTMs) in the NIR-Ⅱ window(1000–1700 nm), especially organic PTMs because of their intrinsic biological safety compared with inorganic PTMs. However, so far, only a few NIR-Ⅱresponsive organic PTMs was explored, and their photothermal conversion efficiencies(PCEs) still remain relatively low. Herein, donor–acceptor conjugated diradical polymers with open-shell characteristics are explored for synergistically photothermal immunotherapy of metastatic tumors in the NIR-Ⅱ window. By employing side-chain regulation, the conjugated diradical polymer TTB-2 with obvious NIR-Ⅱ absorption was developed, and its nanoparticles realize a record-breaking PCE of 87.7% upon NIR-Ⅱ light illustration. In vitro and in vivo experiments demonstrate that TTB-2 nanoparticles show good tumor photoablation with navigation of photoacoustic imaging in the NIR-Ⅱ window, without any side-effect. Moreover, by combining with PD-1 antibody,the pulmonary metastasis of breast cancer is high-effectively prevented by the efficient photo-immunity effect. Thus, this study explores superior PTMs for cancer metastasis theranostics in the NIR-Ⅱ window, offering a new horizon in developing radical-characteristic NIR-Ⅱ photothermal materials.