High-performance and robust high-temperature polymer electrolyte membranes with moderate microphase separation by implementation of terphenyl-based polymers

Acid loss and plasticization of phosphoric acid(PA)-doped high-temperature polymer electrolyte membranes(HT-PEMs)are critical limitations to their practical application in fuel cells.To overcome these barriers,poly(terphenyl piperidinium)s constructed from the m-and p-isomers of terphenyl were synthesized to regulate the microstructure of the membrane.Highly rigid p-terphenyl units prompt the formation of moderate PA aggregates,where the ion-pair interaction between piperidinium and biphosphate is reinforced,leading to a reduction in the plasticizing effect.As a result,there are trade-offs between the proton conductivity,mechanical strength,and PA retention of the membranes with varied m/p-isomer ratios.The designed PA-doped PTP-20m membrane exhibits superior ionic conductivity,good mechanical strength,and excellent PA retention over a wide range of temperature(80–160°C)as well as satisfactory resistance to harsh accelerated aging tests.As a result,the membrane presents a desirable combination of performance(1.462 W cm^(-2) under the H_(2)/O_(2)condition,which is 1.5 times higher than that of PBI-based membrane)and durability(300 h at 160°C and 0.2 A cm^(-2))in the fuel cell.The results of this study provide new insights that will guide molecular design from the perspective of microstructure to improve the performance and robustness of HT-PEMs.

Polymerization-induced microphase separation of polymer-polyoxometalate nanocomposites for anhydrous solid state electrolytes

Solid-state electrolytes(SSEs)with high ionic conductivity,mechanical stability,and high thermal stability,as well as the stringent requirement of application in high-temperature fuel cells and lithium-ion batteries is receiving increasing attention.Polymer nanocomposites(PNCs),combining the advantages of inorganic materials with those of polymeric materials,offer numerous opportunities for SSEs design.In this work,we report a facile and general one-pot approach based on polymerization-induced microphase separation(PIMS)to generate PNCs with bi-continuous microphases.This synthetic strategy transforms a homogeneous liquid precursor consisting of polyoxometalates(POMs,H_(3)PW_(12)O_(40),Li_(7)[V_(15)O_(36)(CO_(3))]),poly(ethylene glycol)(PEG)macro-chain-transfer agent,styrene and divinylbenzene monomers,into a robust and transparent monolith.The resulting POMs are uniformly dispersed in the PEG block(PEG/POM)to form a conducting pathway that successfully realizes the effective transfer of protons and lithium ions,while the highly cross-linked polystyrene domains(P(S-co-DVB))as mechanical support provide outstanding mechanical properties and thermal stability.As the POM loading ratio up to 35 wt%,the proton conductivity of nanocomposite reaches as high as 5.99×10^(-4) S/cm at 100℃ in anhydrous environment,which effectively promotes proton transfer under extreme environments.This study broadens the application of fuel cells and lithium-ion batteries in extreme environments.

Flexible coatings with microphase separation structure attained by copolymers and ultra-fine nanoparticles for endurable antifouling

Incorporating antibacterial agent into biomimetic coating inspired by natural organisms with micronano structure surface has generated more interest for antifouling applications.In this work,poly(dimethylsiloxane)(PDMS)-based triblock copolymers and sub-20 nm nanoparticles Ag and heterogeneous Fe_(3)O_(4)-coated Ag(Fe_(3)O_(4)@Ag)were used to construct microphase separation topography with oriented copolymer blocks structure.The artificial surface was verified by atomic force microscopy and scanning electron microscopy images.Meanwhile,the surface exhibited relative stable hydrophobic property,which was demonstrated by the water contact angle and dynamic air-bubble contact angle measurements.Consequently,after immersed in BSA solution 24 h and 720 h,the actual BSA absorption amount of the surface with Fe_(3)O_(4)@Ag nanoparticles was as low as 10%and 27%that of the initial BSA amount,respectively.Moreover,the surface also showed remarkable antibacterial performance,which effectively suppressed the growth rate of Escherichia coli.The strategy of constructing the flexible micro p hase separation structure by introducing heterogeneous inorganic antibacterial nanoparticles into a block copolymer substrate opens up a new way to create an antifouling surface coating.

Influence of Diisocyanate on Polyurethane Elastomers Which Crosslinked by β-Cyclodextrin

A series of polyurethane elastomers (PUEs) were synthesized by using β-cyclodextrin (β-CD) as cross-linker from aliphatic, alicyclic, aromatic diisocyanates, and polyol. The PUEs were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), swelling test, hardness test and tensile test. The influence of diisocyanate on microphase separation and properties of PUEs was evaluated.

Nanoindentation Measurements of Mechanical Properties of Polyurethane Elastomers Which Crosslinked by β-Cyclodextrin

A series of PUEs which use β-CD as cross-linker were synthesized. Nanoindentation measurements of mechanical properties of these PUEs were made. Load and depth sensing indentation and nano DMA mode were used to evaluate mechanical properties of PUEs in nano-scale. The difference between the results from two modes proved the microphase separation in PUEs and to investigate PUE from hard domains and soft domains was of great significance.

Solvent‑aided phase separation in hydrogel towards significantly enhanced mechanoresponsive strength

Understanding working principles and thermodynamics behind phase separations,which have significant influences on condensed molecular structures and their performances,can inspire to design and fabricate anomalously and desirably mechanoresponsive hydrogels.However,a combination of techniques from physicochemistry and mechanics has yet been established for the phase separation in hydrogels.In this study,a thermodynamic model is firstly formulated to describe solvent-aided phase and microphase separations in the hydrogels,which present significantly improved mechanoresponsive strengths.Flory-Huggins theory and interfacial energy equation have further been applied to model the thermodynamics of concentration-dependent and temperature-dependent phase separations.An intricately detailed phase map has finally been formulated to explore the working principle.The thermodynamic methodology of phase separations,combined with the constitutive stress-strain relationships,has a great potential to explore the working mechanisms in mechanoresponsive hydrogels.

Self-assembly Promoted Crystallization of Diblock Copolypeptoids in Solution

Comprehensive Summary,Great efforts have been lately devoted to fabricating well-defined nanostructures using crystallization-driven self-assembly(CDSA)strategy.The influence of self-assembly on crystallization is also of great interest.Here,a series of amphiphilic diblock copolypeptoids poly(N-allylglycine)-b-poly(N-octylglycine)modified with cysteamine hydrochloride((PNAG-g-NH_(2))-b-PNOG)were synthesized by ring-opening polymerization(ROP)and post-polymerization functionalization.The diblock copolypeptoid is comprised of one hydrophobic crystalline PNOG block and one hydrophilic amorphous block,which can aggregate into nanostructured assemblies with soluble PNAG-g-NH_(2) as the corona layer and PNOG as the inner core in aqueous solution.With a systematic study by differential scanning calorimetry(DSC)and wide-angle X-ray scattering(WAXS),we demonstrated that the self-assembly of the block copolymers strengthens the crystallization of the PNOG block.

Macroscopic Regulation of Hierarchical Nanostructures in Liquid-crystalline Block Copolymers towards Functional Materials

The great potential of liquid-crystalline block copolymers(LCBCs)containing photoresponsive mesogens toward novel applications in photonics and nanotechnology has been attracting increasing attention,due to the combination of the inherent property of microphase separation of block copolymers and the hierarchically-assembled structures of liquid-crystalline polymers(LCPs).The periodically ordered nanostructures in bulk film of LCBCs can be acquired by supramolecular cooperative motion,derived from the interaction between liquid-crystalline elastic deformation and microphase separation,which are able to improve physical properties of polymer film toward advanced functional applications.Moreover,various micro/nano-patterned structures have been fabricated via light manipulation of photoresponsive LCBCs with good reproducibility and mass production.Thanks to recent developments in synthesis and polymerization techniques,diverse azobenzene-containing LCBCs have been designed,resulting in the creation of a wide variety of novel functions.This review illustrates recent progresses in macroscopic regulation of hierarchical nanostructures in LCBCs towards functional materials.The existing challenges are also discussed,showing perspectives for future studies.

Modeling of specific structure crystallization coupling with dissolution

In this paper,the research framework for specific structure crystallization modeling has been proposed in which four steps are required in order to investigate the rigorous crystallization modeling by thermodynamics.The first is the activity coefficient model of the solution,the second is Solid-Liquid equilibrium,the third and fourth are the dissolution and crystallization kinetics modeling,respectively.Our investigations show that the mechanisms of complex structure formation and microphase transition can be analyzed by combining the dissolution and crystallization kinetics modeling.Moreover,the formation mechanism of the porous KCl has been analyzed,which may provide a reference for the porous structure formation in the advanced material synthesis.

Double-Cable Conjugated Polymers with Fullerene Pendant for Single-Component Organic Solar Cells

In this work,the“functionalization-polymerization”(FP)method has been used to construct fullerene-contained double-cable conjugated polymers with“donor-acceptor”backbones.It was realized via synthesizing a fullerene-contained monomer and performing Stille polymerization.With this method,a series of double-cable conjugated polymers with different fullerene contents were developed and applied into single-component organic solar cells.The power conversion efficiencies(PCEs)based on these polymers increased from 0.71%to 1.71%with the enhanced fullerene contents.The relatively low PCEs might be originated from the poor microstructure in these polymers.These new conjugated polymers with molecular heterojunction would show potential application in organic electronic devices.

Designing Tough,Printable,and Adaptable Eutectogels with Multinetworks via Synergy of Rapid Orthogonal Photopolymerizations and Solvent Effect in Seconds

Achieving a straightforward design of tough,printable,and adaptable polymeric eutectogels is still challenging in related fields due to the uncontrollable polymerization and solvent-exchanging processes,and inherent contrasting multiple networks.Here,we report a one-step synergistic strategy based on ruthenium chemistry-catalyzed photopolymerization and solvent effect for preparing high-performance eutectogels.This orthogonal ruthenium photochemistry helps multinetworks formation via phenol-coupling of gelatin and copolymerization of acrylamide(AAm)and[2-(methacryloyloxy)ethyl]trimethylammonium tetrafluoroborate(META)monomers in seconds.The obvious difference in the supramolecular interactions of free AAm monomers and polymerized units in P(AAm-co-META)with deep eutectic solvents(DESs)significantly promotes the microphase-separation behavior in eutectogels.Consequently,the in situ polymerization and microphase-separation behavior enable the as-prepared eutectogel materials to have excellent mechanical properties(stress of∼1.2 MPa),toughness(∼4.0 MJ m^(−3)),elasticity,adaptivity,and conductivity(∼0.5 S m^(−1)at room temperature).Also,the critical strength of the resultant eutectogels can be modulated by varying the DES constituents.This rapid and well-controlled synergistic approach is compatible with extrusion printing techniques to make flexible sensors with high sensitivities and response times to detect pressure in a range of 0–500 kPa.Such a general and simple strategy has application potential in biological,engineering,and material sciences.