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Polymerized ionic liquid-based block copolymer obtained by the functionalization of polystyrene-block-poly(4-vinylpyridine) with chiral auxiliaries demonstrated self-assembled helical nanofibrils with inversion of helical sense.

A worldwide steady increase in oily wastewater, due to oil spillage and various industrial discharges, requires immediate efforts toward development of an effective strategy and materials to preserve the natural water bodies. Designing a superwettable fibrous membrane of robust structure and anti-fouling property for efficient separation of oil-water mixtures and emulsions is therefore highly demanding. The electrospun fibrous membrane, which possesses porosity and flexibility and properties including superwettability and tunable functionality, can be considered as apposite materials for this cause. In this approach, we combined two strategies, viz., Pickering emulsion and near gel resin (nGR) emulsion electrospinning together to produce a fibrous nanocomposite membrane for efficient oil-water separation and demulsification. nGR Pickering emulsions were stabilized using hydrophilic SiO

Confined crystallization behavior of poly(ethylene oxide) (PEO) was studied in electrospun core-shell nanofibers and beads, respectively, using DSC. The core-shell structure consisted of PEO core and polystyrene (PS) shell. It was observed that the morphology of PEO core changed from continuous to discrete domains when the core spinning solvent was switched from water to chloroform. This significantly influenced the crystallization behavior of PEO such that whereas the crystallization nucleation mechanism was heterogeneous for nanofibers with continuous PEO core, it became fractionated for nanofibers with discontinuous PEO core. The relaxation of the PEO domains, in the nanofibers with discontinuous core, via thermal annealing above the glass transition temperature of PS shell, markedly increased homogenous nucleation contribution in the crystallization. This plausibly was due to relaxation of PEO domains through domain breakup and coalescence process resulting in higher fraction of nanosized PEO domains.

We report on the surprising observation of a unique perforated lamellar (PL) morphology in a mixture of an asymmetric polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer and CdSe–Cd...

An in situ encapsulation strategy for embedding sulfur within carbon (S@C) fiber through a sustainable and scalable route using waste cotton cloth as a fiber template, is developed. The S@C fibers with reasonably high sulfur content of ∼71% displayed promising electrochemical performance when employed as a cathode material for a lithium sulfur battery (LSB). The S@C fibers developed herein have the potential to be used as a promising cathode material for other sulfur-based batteries as well.

1D nanofibers with higher surface area, small pore size, high porosity, good electrical conductivity, and relatively high production rate with high fiber interconnectivity have gained attention as ...

We report that the use of multiple associating interactions between polymer chains results in rich rheological properties of their solutions and, hence, could be used as a powerful tool to enhance ...

We investigate the self-assembly of cylinder-forming polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymers (BCP) mixed with metal nanoparticles (NP) coated with short-chain polystyrene (PS) ligands. The NP formed hierarchical superstructures under confinement of cylindrical PS domains of PS-b-P4VP BCP. The complexity of NP superstructures was found to depend on the ratio between PS cylindrical domain size and NP size (DC/DNP). As the DC/DNP ratio increased, the number of NP layers normal to the cylinder axis also increased. However, the packing density of the NP decreased at higher DC/DNP. Furthermore, the morphology of the structures obtained during different solvent casting conditions revealed that the initial clustering of NP and micellization around these clusters act as a precursor for the subsequent formation of closely packed structures of NP in cylinders. The experimental results were further supported by modeling results obtained from molecular dynamics (MD) simulation. Based on MD simulations, we constructed structural phase diagram of nanoparticle assemblies in the presence of asymmetric diblock copolymers comprising short NP-attractive blocks. The MD simulation results indicate that NP undergo transition from spherical to cylindrical assemblies depending on the NP size, the overall concentration of components and the degree of affinity of the minor block to NP.

Electrospun fibers and matrices have been researched for their utility in various fields; however, because of poor mechanical strength and loss of structural integrity, their commercial viability is limited. A near gel resin (nGR) of polystyrene (PS) was used in the present approach to fabricate cross-linked fibrous matrices of better mechanical strength and oil adsorption while retaining the structural integrity. Electrospinnability of nGR was assessed in bulk (i.e., in styrene monomer) and solution (i.e., in dimethyl formamide) forms with variations in formulation and electrospinning conditions. Ultimately, a uniform cross-linked fibrous matrix of PS was prepared using an oil-in-water emulsion, where the oil phase composed of a monomer (styrene), an initiator (benzoyl peroxide), and a cross-linker (divinylbenzene) was dispersed in a continuous phase of aqueous poly(vinyl alcohol) (PVA). The monomer conversion in the oil phase was carried out below the gel point, and the nGR of PS formed in dispersed droplets was electrospun to fabricate uniform fibrous matrices with the help of a template polymer, that is, PVA. The effect of various material and process parameters on the gelation behavior, electrospinnability, and fiber uniformity was studied and optimized to produce uniform core-sheath fibrous matrices of cross-linked PS. Postelectrospinning heat treatment of matrices was carried out to achieve complete monomer conversion and cross-linking. Fiber formation behavior of the emulsion was assessed using ionic and nonionic surfactants. The cross-link density of the matrices was optimized to achieve the desired structural morphology and dimensional stability. The process of fabrication of emulsion electrospun cross-linked fibers can be further extended to a variety of other monomers in order to enhance the suitability of fibrous matrices for many applications.

A macrocellular nanocomposite scaffold of crosslinked poly(e-caprolactone) was made by conducting a ring-opening polymerization of an emulsifier-free Pickering high internal phase emulsion (HIPE). The Pickering HIPE formulation, stabilized using hydrophobically modified silica nanoparticles (mSiNPs), showed extraordinary stability up to a temperature of polymerization as high as 120 °C. The nanocomposite scaffolds demonstrated high porosity and a liquid uptake capacity of up to ∼23 g g−1. The scaffolds decorated with mSiNPs were mechanically robust and showed high resiliency under cyclic compression tests.

Catalytically active porous and hollow titania nanofibers encapsulating gold nanoparticles were fabricated using a combination of sol-gel chemistry and coaxial electrospinning technique. We report the fabrication of catalytically active porous and hollow titania nanofibers encapsulating gold nanoparticles (AuNPs) using a combination of sol-gel chemistry and coaxial electrospinning technique. The coaxial electrospinning involved the use of a mixture of poly(vinyl pyrrolidone) (PVP) and titania sol as the shell forming component, whereas a mixture of poly(4-vinyl pyridine) (P4VP) and pre-synthesized AuNPs constituted the core forming component. The core-shell nanofibers were calcined stepwise up to 600 °C which resulted in decomposition and removal of the organic constituents of the nanofibers. This led to the formation of porous and hollow titania nanofibers, where the catalytic AuNPs were embedded in the inner wall of the titania shell. The catalytic activity of the prepared Au@TiO2 porous nanofibers was investigated using a model reaction of catalytic reduction of 4-nitrophenol and Congo red dye in the presence of NaBH4. The Au@TiO2 porous and hollow nanofibers exhibited excellent catalytic activity and recyclability, and the morphology of the nanofibers remained intact after repeated usage. The presented approach could be a promising route for immobilizing various nanosized catalysts in hollow titania supports for the design of stable catalytic systems where the added photocatalytic activity of titania could further be of significance.

The drive for commercializing high energy density lithium-sulfur batteries is leading to the development of various material architectures for suppressing the notorious “shuttle effect” of intermediate polysulfides and improve cycle life. Inspired by the structural features of plant roots protecting soil erosion, herein, we report a novel strategy to use poly(3,4-ethylenedioxythiophene):polystyrene sulfonate-sulfur@polyacrylonitrile electrospun nanofibers as flexible additives in the cathode of lithium-sulfur batteries to trap lithium polysulfides and suppress their dissolution into liquid electrolyte. The nanofibers consist of in-situ grown sulfur particles, embedded inside porous polyacrylonitrile shell and coated with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate. The electrochemical performance of lithium-sulfur batteries using poly(3,4-ethylenedioxythiophene):polystyrene sulfonate-sulfur@polyacrylonitrile nanofiber incorporated sulfur hybrid cathode shows a significantly better cycle stability and excellent rate capability compared to the bare sulfur cathode owing to the adsorption effect of the nanofibers. Even after 500 cycles at a high rate of 0.5 C, the capacity retention is approximately 41% of the initial capacity with average columbic efficiency above 94%. This work offers a novel approach to fabricate viable lithium-sulfur batteries and possibly pave the way to further develop innovative flexible additives for practically applicable lithium-sulfur batteries.

A high internal phase emulsion based ring-opening polymerization (HIPE-ROP) of ɛ-caprolactone (CL) was conducted to fabricate macroporous scaffold in a single-step. An oil-in-oil HIPE of CL was formed using high molecular weight olefin (C10-C16) dispersed in continuous medium comprised of CL, a bifunctional cross-linking monomer bis-ɛ-caprolactone-4-yl (BCY) and catalyst stannous octoate (Sn(Oct)2). The emulsion was stabilized using nonionic surfactant, pluronic F127 and polymerization was conducted at 120 °C without any inert atmosphere for a period of 8 h. Complete monomer conversion and cross-linking was achieved and am acroporous scaffold of desired shape was obtained, having in-situ generated porosity and interconnected pores. All chemicals were purposely used without any purification and the high temperature process prevented deactivation of catalyst. The HIPE-ROP developed in this way was found to be highly feasible for conducting otherwise moisture sensitive organo-metallic catalyst based ROP. The morphology of HIPE was directly transferred to macroporous structure of the scaffold in this process where pore size was reproducibly controlled by variation in volume fraction of dispersed phase and cross-link density. The resultant macroporous scaffold showed superior compressive loading and swelling capacity. The porous scaffolds also exhibited excellent osteoblast (MG63) attachment and proliferation. HIPE-ROP based macroporous scaffold of cross-linked PCL thus developed paved a new route to create porous scaffolds of aliphatic polyesters in a single step. The method also reflected high commercial viability by potential conversion into a continuous process.

In the present study, we demonstrate the fabrication of multifunctional nanofibers, loaded with CdSe quantum dots (QDs) and sulforhodamine 101 (S101) dye, via the self-assembly process of a polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP). The CdSe QDs and S101 dye were simultaneously incorporated in the cylindrical domains, constituted of P4VP blocks, of the self-assembled BCP structure. The cylindrical domains subsequently were isolated as individual nanofibers via the selective-swelling approach. The confinement imposed due to the nano-dimension geometry of the cylindrical domains enabled the QDs and S101 dye to localize within their Förster radius enabling an efficient fluorescence resonance energy transfer (FRET) between them. The mean lifetime of donor emission varied from 4.56 to 3.38 ns with the change in the ratio of S101 dye and CdSe QDs within the nanofibers. Furthermore, using efficiency measurements and the corresponding Förster distances, donor-acceptor distances were determined. Moreover, the kinetics of energy transfer from CdSe QDs to S101 was studied by the Poisson binding model, to understand the interactions between CdSe QDs and S101 dye molecules. The numbers of dye molecules per CdSe QD were determined, by assuming random distribution of S101 dye molecules around the CdSe QDs in the nanofibers. The results showed that the number of dye molecules per QD increased with increasing concentration of dye molecules in the nanofibers. The resulting multifunctional nanofibers could have potential applications in optoelectronics, photonics and sensors which utilize the FRET process.

Herein, photoluminescent poly(4-vinylpyridine)-based ionic liquids (PILs) bound with D- and L-histidine were synthesized for the first time and fully characterized by NMR, IR and UV-vis spectroscopy and TG analysis. The chiral PILs self-assembled into helical aggregates, which were isolated by two different methods, namely, by the addition of a poor solvent and by the slow evaporation of solvent. The isolated nanofibers, comprising helical aggregates, were observed to be thin in the case of the former and thick in the case of the latter method. Moreover, the helical nanofibers formed herein were several hundreds of micrometers long. The aggregation of the PIL chains in the helical nanofibers was further revealed by the significantly red-shifted photoluminescence spectra.

Fabrication of block copolymer (BCP) template-assisted nano-catalysts has been a subject of immense interest in the field of catalysis and polymer chemistry for more than two decades now. Different methods, such as colloidal route, on-substrate methods, bulk self-assembly approaches, combined approaches, and many others have been used to prepare such nano-catalysts. The present review focuses on the advances made in this direction using diblock, triblock, and other types of BCP self-assembled structures. It will be shown how interestingly, researchers have exploited the features of tunable periodicity, domain orientation, and degree of lateral orders of self-assembled BCPs by using fundamental approaches, as well as using different combinations of simple methods to fabricate efficient catalysts. These approaches allow for fabricating catalysts that are used for the growth of single- and multi-walled carbon nanotubes (CNTs) on the substrate, size-dependent electrooxidation of the carbon mono oxide, cracking of 1,3,5-triisopropylbenzene (TIPB), methanol oxidation, formic acid oxidation, and for catalytic degradation of dyes and water pollutants, etc. The focus will also be on how efficient and ease-of-use catalysts can be fabricated using different BCP templates, and how these have contributed to the fabrication of different nano-catalysts, such as nanoparticle array catalysts, strawberry and Janus-like nanoparticles catalysts, mesoporous nanoparticles and film catalysts, gyroid-based bicontinuous catalysts, and hollow fiber membrane catalysts.

In the present work, we have studied the influence of gold nanoparticles (AuNPs) on the photoluminescence (PL) behavior of cadmium selenide (CdSe) quantum dots (QDs) confined in spatially separated soft nanoscale cylindrical domains. These cylindrical domains, in the form of hairy core-shell nanofibers, were fabricated via cooperative self-assembly of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) mixed with pre-synthesized CdSe QDs and AuNPs. The CdSe QDs and AuNPs were simultaneously incorporated in the P4VP cylindrical domains of the self-assembled BCP structure. It was found that the confinement imposed by the nanometer-sized cylindrical core resulted in the localization of the CdSe QDs and AuNPs in close proximity. Notably, it was observed that the PL intensity of the CdSe QDs could be manipulated by varying the amount of AuNPs present in the cylinder core. Interestingly, in the presence of a very low fraction of AuNPs, the PL intensity of the CdSe QDs increased compared to the AuNPs-free system. However, further increase in the fraction of AuNPs led to gradual quenching of the photoluminescence intensity. The PL enhancement and quenching plausibly was due to the interplay between the energy transfer due to surface plasmon coupling and FRET/electron transfer from QDs to the AuNPs. The resulting functional nanofibers could have potential applications in sensing, bioimaging, and optoelectronic devices.

Circularly polarized luminescence (CPL) reflects the chiroptical properties at the lowest excited state of the emitter. Thus, a wide range of applicability of these materials is in order, e.g. optical sensing. Polymeric systems possess complex vibronic states in ground states and excited states, which presents a challenge to carefully design and amplify the CPL signals from functional polymers. In this chapter, the fundamentals of CPL are briefly introduced followed by a review of several π-conjugated and coordination polymers exhibiting CPL signals. In addition, the chiroptical properties will be discussed based on the CPL signals of the polymer materials.

A macrocellular nanocomposite scaffold of crosslinked poly(ε-caprolactone) was made by conducting a ring-opening polymerization of an emulsifier-free Pickering high internal phase emulsion (HIPE). The Pickering HIPE formulation, stabilized using hydrophobically modified silica nanoparticles (mSiNPs), showed extraordinary stability up to a temperature of polymerization as high as 120 °C. The nanocomposite scaffolds demonstrated high porosity and a liquid uptake capacity of up to ∼23 g g-1. The scaffolds decorated with mSiNPs were mechanically robust and showed high resiliency under cyclic compression tests.

Phase behaviour as well as phase transitions of $$4'$$ -pentyl-4-biphenylcarbonitrile (5CB) liquid crystal (LC) confined in an amorphous polymer matrix of electrospun nanofibres were investigated. The nanofibres were fabricated from simple monoaxial electrospinning using 5CB/polymer mixtures as well as coaxial electrospinning, where the polymer solution and neat 5CB constituted the shell- and core-forming fluids, respectively. The 5CB was found to be miscible with polystyrene (PS) and poly(4-vinyl pyridine) (P4VP). This was evident from the sharp drop in the glass transition temperature ( $$T_{\mathrm{g}}$$ ) of PS and P4VP in their mixtures with 5CB. Hence, the phase transitions of 5CB were completely suppressed in its mixture with PS and P4VP in electrospun nanofibres as ascertained from DSC and polarized optical microscopy measurements. However, the electrospun nanofibres composed of poly(vinyl pyrrolidone) (PVP) and 5CB showed phase-separated morphology. The phase-separated morphology was unambiguously characterized using SEM and TEM measurements. Furthermore, the phase separation resulted in 5CB exhibiting its liquid crystalline characteristics. However, the radial constraint of the nanofibres led to the formation of small-sized 5CB domains with limited spatial connectivity, which resulted in deviation from the known phase-transition characteristics of 5CB. It was also observed that the inherent orientation of the nanofibres favours the nematic to crystalline transition in the blend nanofibres. The present study gives new insight and understanding about phase behaviour of LC in electrospun polymer fibre and has technological relevance for the design of LC-based flexible fibrous components with tunable optical, thermal and dielectric properties.

Lithium-sulfur batteries (LSBs) are the promising next-generation energy storage devices; however, the uncontrolled shuttle effect and sluggish redox kinetics severely hinder their commercial success. To solve these barriers, herein, a heterostructure constructed from CoFe2O4 and SnO2 decorated over the carbon nanofiber framework (CoFe@SnCNF) is reported as a sulfur redox catalyst in the cathode of LSB. A synergism between the multiple adsorptive and catalytic sites of the heterostructure enables an efficient lithium polysulfide (LiPS) entrapment and expedites their conversion, meanwhile the carbon nanofiber framework provides a long-range electrical conduction. Based on these merits, the CoFe@SnCNF integrated sulfur cathode with an areal sulfur loading of ~ 2.2 mg cm−2 retained 71.1 % of initial capacity after 100 cycles at 0.2 C, and showed excellent cyclability with a capacity fading rate of only 0.11 % over 200 cycles at 0.5 C. Even under a raised sulfur loading of 5.3 mg cm−2, the cathode still showed an impressive performance with an initial capacity of 442.3 mAh g−1 that retained 78.1 % after 80 cycles. The findings of this work shed light on the feasibility for further development of novel heterostructure by synergistically coupling various polysulfide adsorbing and catalyzing materials.

The utilization and applications of biopolymer based electrospun matrices has expanded in various fields because of their advantageous features, however due to the poor mechanical strength their true potential has still not been realized. Enhancing mechanical strength of electrospun matrices is a long sought-after goal which is achieved by maximizing the interactions in inclusion complex (IC) of poly(ɛ-caprolactone) (PCL) with urea, in this work. The ratio of urea was varied with respect to PCL and changes in the enthalpy of fusion (ΔHf) for IC thus formed were analyzed using DSC. Binding efficiency (BE) of PCL and urea within the IC was calculated using ΔHf, which was reproducibly altered by varying urea to PCL ratio. The extent of hydrogen bonding between PCL and urea, varied in this way, was also confirmed by FTIR and XRD analysis. PCL and urea-based IC samples were electrospun to fabricate uniform fibrous matrices which upon selective removal of urea showed superior mechanical strength as compared to neat PCL matrix. The crystallinity of coalesced PCL was found to be significantly enhanced, up to 34%, in IC with urea as a result of better orientation of PCL chains. A memory effect on crystallization was ultimately seen where characteristics of coalesced PCL matrix were found to be retained even after dissolution of matrix in acetic acid and electrospinning it again.

Recently, ionic liquid based solid electrolytes is of great interest for the development of safe rechargeable lithium batteries. In this study, a solvent free approach to incorporate a novel type of binary mixture solid electrolyte composed of room temperature solid, crystalline, ionic liquid 1-butyl-1,4-diazabicyclo [2.2.2] octan-1-ium bis(trifluoromethanesulfonyl) imide (C4DTFSI) and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) within an inert, porous host membrane is designed. The thermal, spectroscopic and electrochemical properties of the electrolyte at varied LiTFSI concentrations are studied. The Li+ transference number of the free-standing solid electrolyte is 0.49 at 25 ℃ having electrochemical stability of more than 5 V vs. Li/Li+. Moreover, the solid electrolyte assembled with LiFePO4 (LFP) cathode and Li anode in half cell configuration showed good cyclability (133 mAh g−1 after 100 cycles at 0.2 C) with Coulombic efficiency above 99 %.