Poly(ethylene oxide)- and Polyzwitterion-Based Thermoplastic Elastomers for Solid Electrolytes.

In this article, ABA triblock copolymer (tri-BCP) thermoplastic elastomers with poly(ethylene oxide) (PEO) middle block and polyzwitterionic poly(4-vinylpyridine) propane-1-sulfonate (PVPS) outer blocks were synthesized. The PVPSPEOPVPS tri-BCPs were doped with lithium bis-(trifluoromethane-sulfonyl) imide (LiTFSI) and used as solid polyelectrolytes (SPEs). The thermal properties and microphase separation behavior of the tri-BCP/LiTFSI hybrids were studied.

Microphase Separation with Sub-3 nm Microdomains in Comb-Like Poly(-alkyl acrylate) Homopolymers Facilitated by Charged Junction Groups between the Main Chains and Side Chains.

The phase structure with a small domain size in polymers is expected to provide a template for lithography to fabricate electronic devices, while the uniformity and thermal stability of the phase structure are vital in lithography. In this work, we report an accurately microphase-separated system of comb-like poly(ionic liquid) (PIL)-based homopolymers containing imidazolium cation junctions between the main chain parts and the long alkyl side chains, poly(1-((2-acryloyloxy)ethyl)-3-alkylimidazolium bromide) (P(AOEAI-Br)). The ordered hexagonally packed cylinder (HEX) and lamellar (LAM) structures with small domain sizes (sub-3 nm) were successfully achieved.

Electrostatic crosslinking-enabled highly asymmetric lamellar nanostructures of polyzwitterionic block copolymers for lithography.

For the bulk self-assembly of traditional diblock copolymers (di-BCPs), lamellar structures only occur when two constituents have similar volume fractions () and two alternating layers tend to have similar thicknesses. Highly asymmetric lamellar (A-LAM) structures, in which the thickness of one layer is several times higher than the other, are hardly formed in di-BCPs, while they have potential applications in nanolithography. In this work, A-LAM structures with different dimensions were constructed using a type of simple linear di-BCP, polystyrene--poly(4-vinylpyridine)propane-1-sulfonate (PS--PVPS) with the polyzwitterionic block PVPS in minority.

PEO-Based Block Copolymer Electrolytes Containing Double Conductive Phases with Improved Mechanical and Electrochemical Properties.

In this work, the advanced all solid-state block copolymer electrolytes (SBCPEs) for lithium-ion batteries with double conductive phases, poly(ethylene oxide)--poly(trimethyl--((2-(dimethylamino)ethyl methacrylate)-7-propyl)-ammonium bis(trifluoromethanesulfonyl) imide) (PEO--PDM-dTFSI)/LiTFSI, were fabricated, in which the charged PDM-dTFSI block contained double quaternary ammonium cations and the PEO block was doped with LiTFSI. The disordered (DIS) and ordered lamellae (LAM) phase structures were achieved by adjusting the composition of the block copolymer and the doping ratio . In addition, the presence of the hard PDM-dTFSI block and the formation of the LAM phase structure resulted in a good mechanical strength of the solid PEO--PDM-dTFSI/LiTFSI electrolyte, and it could maintain a high level of 10 Pa at 100 °C, which was around 10,000 times stronger than that of the PEO/LiTFSI electrolyte.

Binary Promoter Improving the Moderate-Temperature Adhesion of Addition-Cured Liquid Silicone Rubber for Thermally Conductive Potting.

The strong adhesion of thermally conductive silicone encapsulants on highly integrated electronic devices can avoid external damages and lead to an improved long-term reliability, which is critical for their commercial application. However, due to their low surface energy and chemical reactivity, the self-adhesive ability of silicone encapsulants to substrates need to be explored further. Here, we developed epoxy and alkoxy groups-bifunctionalized tetramethylcyclotetrasiloxane (DH-MSEP) and boron-modified polydimethylsiloxane (PDMS-B), which were synthesized and utilized as synergistic adhesion promoters to provide two-component addition-cured liquid silicone rubber (LSR) with a good self-adhesion ability for applications in electronic packaging at moderate temperatures.

Fabrication of High χ-Low Block Copolymers with Thermally Stable Sub-5 nm Microdomains Using Polyzwitterion as a Constituent Block.

In this work, we used zwitterionic poly(4-vinylpyridine) propane-1-sulfonate (PVPS) as a constituent block to construct high χ-low block copolymers (BCPs) with different neutral polymers as the other block, including polystyrene (PS), poly(ethylene oxide) (PEO), and poly(l-lactide) (PLLA). Lamellar structures with sub-5 nm microdomains were observed in all three types of BCPs. Due to the tendency of self-aggregation induced by electrostatic interaction in polyzwitterion, the Flory-Huggins parameters (χ) between PVPS and most neutral polymers are relatively high, which provides a facile and efficient way to fabricate high χ-low BCPs.

Promoters for Improved Adhesion Strength between Addition-Cured Liquid Silicone Rubber and Low-Melting-Point Thermoplastic Polyurethanes.

A polydimethylsiloxane armed with epoxy, alkoxy and acrylate groups was synthesized from silanol terminated-PDMS and epoxy and acrylate groups functionalized silane coupling agents, and utilized as the adhesion promoter (AP) to prepare addition-cured liquid silicone rubber that exhibited self-adhesion ability (SA-LSR) with biocompatible thermoplastic polyurethanes (TPU) sheets. The structural characteristics of AP were characterized by Fourier transform infrared (FTIR) spectroscopy, which demonstrated the strong adhesion to polyester-based TPU sheets due to a sufficient amount of acrylate groups, epoxy groups and silanol groups obtained by the hydrolysis of alkoxy groups. In detail, the peel-off strength of SA-LSR and TPU joints reached up to 7.

Icarisid II promotes proliferation and neuronal differentiation of neural stem cells via activating Wnt/β-catenin signaling pathway.

Adult neurogenesis plays a vital role in maintaining cognitive functions in mammals and human beings. Mobilization of hippocampal neurogenesis has been regarded as a promising therapeutic approach to restore injured neurons in neurodegenerative diseases including Alzheimer's disease (AD). Icarisid II (ICS II), an active ingredient derived from Epimedii Folium, has been reported to exhibit multiple neuroprotective effects.

Simultaneous Improvement of Ionic Conductivity and Mechanical Strength in Block Copolymer Electrolytes with Double Conductive Nanophases.

The most daunting challenge of solid polymer electrolytes (SPEs) is the development of materials with simultaneously high ionic conductivity and mechanical strength. Herein, SPEs of lithium bis-(trifluoromethanesulfonyl)imide (LiTFSI)-doped poly(propylene monothiocarbonate)-b-poly(ethylene oxide) (PPMTC-b-PEO) block copolymers (BCPs) with both blocks associating with Li ions are prepared. It is found that the PPMTC-b-PEO/LiTFSI electrolytes with double conductive phases exhibit much higher ionic conductivity (2 × 10 S cm at r.

Interfacial self-assembly of amphiphilic conjugated block copolymer into 2D nanotapes.

In the present work, the evaporation-induced interfacial self-assembly behavior of an amphiphilic conjugated polymer, poly(3-hexylthiophene)-b-poly(acrylic acid) (P3HT-b-PAA), at the oil-water interface is explored. Novel 2D nanotapes of P3HT-b-PAA are prepared via the interfacial self-assembly. It is inferred that P3HT segments adopt a special conformation at the oil-water interface, which facilitates the packing of alkyl side chains and π-π interaction.

Self-Assembled Amphiphilic Block Copolymers/CdTe Nanocrystals for Efficient Aqueous-Processed Hybrid Solar Cells.

Due to their low cost and high efficiency, polymer/nanocrystal hybrid solar cells (HSCs) have attracted much attention in recent years. In this work, water-soluble hybrid materials consisting of amphiphilic block copolymers (ABCPs) and cadmium telluride nanocrystals (CdTe NCs) were used as the active layer to fabricate the HSCs via aqueous processing. The ABCPs composed of poly(3-hexylthiophene) (P3HT) and poly(acrylic acid) (PAA) self-assembled into ordered nanostructured micelles which then transformed to nanowires by comicellization with P3HT additives.

Crystallization-driven one-dimensional self-assembly of polyethylene-b-poly(tert-butylacrylate) diblock copolymers in DMF: effects of crystallization temperature and the corona-forming block.

Crystallization-driven self-assembly of polyethylene-b-poly(tert-butylacrylate) (PE-b-PtBA) block copolymers (BCPs) in N,N-dimethyl formamide (DMF) was studied. It is found that all three PE-b-PtBA BCPs used in this work can self-assemble into one-dimensional crystalline cylindrical micelles. When the BCP solution is cooled to crystallization temperature (Tc) from 130 °C, the seed micelles may be produced via two competitive processes in the initial period: stepwise micellization/crystallization and simultaneous crystallization/micellization.

Chain structure, aggregation state structure, and tensile behavior of segmented ethylene-propylene copolymers produced by an oscillating unbridged metallocene catalyst.

Segmented ethylene-propylene copolymers (SEPs) with different propylene contents were prepared by an unbridged metallocene bis(2,4,6-trimethylindenyl)zirconium dichloride [(2,4,6-Me3Ind)2ZrCl2] catalyst. Due to oscillation of the unbridged ligands in the catalyst, the SEPs are composed of segments with low propylene contents, alternated by the segments with high propylene contents. Such a chain structure was verified by (13)C NMR and successive self-nucleation and annealing (SSA).

Effect of local chain deformability on the temperature-induced morphological transitions of polystyrene-b-poly(N-isopropylacrylamide) micelles in aqueous solution.

The effect of temperature on the micellar morphology of two polystyrene-b-poly(N-isopropylacrylamide) (PS-b-PNIPAM) diblock copolymers in an aqueous solution was investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). At 25 °C, a mixture of vesicles and spheres are observed for the micelles of PS65-b-PNIPAM108, while PS65-b-PNIPAM360 exhibits mixed cylindrical and spherical micellar morphology. Upon increasing the temperature, the micellar morphology becomes spherical for PS65-b-PNIPAM108 at 60 °C and for PS65-b-PNIPAM360 at 40 °C.

Preparation and characterization of V-shaped PS-b-PEO brushes anchored on planar gold substrate through the trithiocarbonate junction group.

Trithiocarbonate group was introduced into the polystyrene-b-poly(ethylene oxide) (PS-b-PEO) block copolymers as the junction of the blocks through RAFT polymerization. Mixed PS and PEO brushes with a V-shape were prepared by anchoring the trithiocarbonate group on the planar gold substrate. The morphology of the V-shaped brushes was characterized by atomic force microscopy (AFM) and the surface composition responsive to solvent treatment was detected by X-ray photoelectron spectroscopy (XPS).

Facile fabrication of amphiphilic gold nanoparticles with V-shaped brushes from block copolymers with a trithiocarbonate group as the junction.

Amphiphilic gold nanoparticles grafted with V-shaped brushes (Au-V-brushes) were prepared by grafting a polystyrene-b-poly(ethylene oxide) (PS-b-PEO) block copolymer with a trithiocarbonate group as the junction to the Au surface. The obtained Au-V-brushes were subjected to solubility test and UV-vis, FT-IR, TEM and DLS characterizations. It is found that the Au-V-brushes are soluble in both water and organic solvents.

Cooperative effect of electrospinning and nanoclay on formation of polar crystalline phases in poly(vinylidene fluoride).

Poly(vinylidene difluoride)/organically modified montmorillonite (PVDF/OMMT) composite nanofibers were prepared by electrospinning the solution of PVDF/OMMT precursor in DMF. Wide-angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM) show that in the bulk of the PVDF/OMMT precursor OMMT platelets are homogeneously dispersed in PVDF and can be both intercalated and exfoliated. It is found that the diameter of the PVDF/OMMT composite nanofibers is smaller than that of the neat PVDF fibers because the lower viscosity of PVDF/OMMT solution, which is attributed to the possible adsorption of PVDF chains on OMMT layers and thus reduction in number of entanglement.

Morphological change of asymmetric oxyethylene/oxybutylene block copolymers induced by montmorillonite.

Two oxyethylene/oxybutylene block copolymers (E(40)B(79) and E(47)B(62)), which exhibit body-centered cubic sphere (bcc) and hexagonally packed cylindrical (hex) melt morphologies in bulk, respectively, were blended with nanoclay of montmorillonite (MMT). The effects of MMT on the morphology and crystallization of E(40)B(79) and E(47)B(62) were studied with small-angle x-ray scattering, wide-angle x-ray diffraction, and differential scanning calorimeter. It is found that the E block in the block copolymers can intercalate into the galleries of MMT, leading to a larger layer spacing than that of neat MMT.

Lamellar orientation in thin films of symmetric semicrytalline polystyrene-b-poly(ethylene-co-butene) block copolymers: effects of molar mass, temperature of solvent evaporation, and annealing.

Orientation of the lamellar microdomains in thin films of three symmetric polystyrene-b-poly(ethylene-co-butylene) block copolymers (S65E155, S156E358, and S199E452) on mica was investigated via atomic force microscopy (AFM), grazing incidence X-ray diffraction (GIXRD) and X-ray photoelectron spectroscopy (XPS). The results show that lamellar orientation in the SxEy block copolymers greatly depends on the molar mass of the block copolymers, the temperature of solvent evaporation, and annealing. The nascent thin film of the low molar mass block copolymer, S65E155, shows a multilayered structure parallel to the mica surface with the PS block at both polymer/mica and polymer/air interfaces, but the high molar mass block copolymers, S156E358 and S199E452, exhibit a structure with lamellar microdomains perpendicular to the mica surface.

Effect of substrate and molecular weight on the stability of thin films of semicrystalline block copolymers.

The thermal stability of the thin film morphology of two symmetric oxyethylene/oxybutylene block copolymers (E76B38 and E114B56) on mica and silicon was investigated via atomic force microscopy (AFM). It is found that morphological transition of EmBn thin films during melting is strongly dependent on the molecular weight of the diblock copolymers and their interaction with the substrate. For E76B38 on mica, a single-layered structure transforms into a double-layered structure upon melting, but the same polymer on silicon retains a single-layered structure after melting and spreads quickly to wet-out the silicon surface.

Effect of substrate surface on dewetting behavior and chain orientation of semicrystalline block copolymer thin films.

Three symmetrical semicrystalline oxyethylene/oxybutylene block copolymers (EmBn) were spin-coated on different substrates including silicon, hydrophobically modified silicon, and mica. The effects of surface property on the dewetting behavior of EmBn thin films and the chain orientation of the crystalline block were investigated with atomic force microscopy and grazing incidence X-ray diffraction . The EmBn thin films on silicon exhibit an autophobic dewetting behavior, while ordinary dewetting occurs for the thin films on modified silicon.