Kinds Of Triblock Copolymers Research Articles

Construction of a flexible, integrated rechargeable Li battery based on a coaxial anode with a carbon fiber core encapsulated in FeNiMnO4 and a nitrogen-doped carbon sheath

A coaxial anode with a carbon fiber core encapsulated in nanocrystalline FeNiMnO4 with a nitrogen-doped carbon sheath was prepared using carbon fiber cloth as the core, FeNiMnO4 nanocrystallite arrays as the first coating layer and nitrogen-doped carbon derived from F127 (a kind of triblock copolymer)-resorcinol-melamine gel as the outer layer. After annealing at 600 °C it was used as the anode material of an all solid flexible lithium ion battery using LiFePO4 as the cathode material and boron nitride modified polyethylene oxide as the electrolyte. The battery had a large areal capacity of ∼1.40 mAh cm−2 and satisfactory cycling stability under different bending and strain states. Annealing below 600 °C leads to incomplete carbonization of the nitrogen-doped carbon and thus a low electrical conductivity while above 600 °C aggregation of FeNiMnO4 nanocrystallites and their detachment during cycling are observed under bending and strain.

Well-defined triblock copolymer/TiO2 composite gel electrolytes for high-performance dye-sensitized solar cells

Two kinds of triblock copolymers (SGT-602 and SGT-604) were prepared and applied to dye-sensitized solar cells (DSSCs). The polymer gel electrolytes with a TiO2 nanofiller achieved comparable efficiencies to liquid-state DSSCs (η: 9.86%), and exhibited excellent long-term device stability under 1 sun illumination at 50 °C.

Ordered mesoporous carbon prepared from triblock copolymer/novolac composites

Ordered mesoporous carbon is synthesized by the organic–organic self-assembly method with novolac as carbon precursor and two kinds of triblock copolymers (Pluronic F127 and P123) as template. The hexagonal structure and a worm-hole structure are observed by TEM. The carbonization temperature is determined by TG and FT-IR. Characterization of physical properties of mesoporous carbon is executed by N2 absorption–desorption isotherms and XRD. The mass ratios of carbon precursor/template affect the textural properties of mesoporous carbon. The mesoporous carbon with F127/PF of 1/1 has lager surface area (670 m2 g−1), pore size (3.2 nm), pore volume (0.40 cm3 g−1), smaller microporous surface area (368 m2 g−1) and wall thickness (3.7 nm) compare to that with F127/PF of 0.5/1 (576 m2 g−1, 2.7 nm, 0.29 cm3 g−1, 409 m2 g−1 and 4.3 nm, respectively). The mesoporous carbon prepared by carbonization at high temperature (700 °C) exhibits lager surface area, lower pore size and pore volume than the corresponding one obtained at 500 °C. The structure and order of the resulting materials are notably affected with types of templates. The mesoporous carbon with P123 as template exhibits worm-hole structure compare to that with F127 as template with hexagonal structure. In general, the pore size of mesoporous carbon with novolac as precursor is smaller than that with resorcinol–formaldehyde as precursor.

Biomolecules Loading and Mesoporous SBA-15 Pore Sizes

The encapsulation and immobilization of biomolecules on solid materials, mesoporous SBA-15, have been studied. Highly ordered hexagonal mesoporous silicates (MPS) with different mean pore sizes have been synthesized using two kinds of triblock copolymers (P123 or L123) as a template. The mixture of tetraethyl orthosilicate (TEOS) and the triblock copolymer (poly(ethylene glycol)poly(propylene glycol)-poly(ethylene glycol)) was stirred and hydrothermally treated at various temperatures to form the MPS structure. Higher temperatures during stirring and hydtrothermal treatment led to the enlargement of pore size. UV-spectrometry was performed to determine the amount of bovine serum albumin (BSA) encapsulated in MPS. It was found that the adsorption processes of BSA on/in MPS could be well described by intraparticle diffusion model.

Interfacial crystalline behavior in glass-fiber/polypropylene composites modified by block copolymer coupling agents

A kind of di-block copolymer polystyrene-block-poly(γ-methacryloxy-propyltrimethoxysilane) (PS-b-PMPS) with different PS block length and a kind of tri-block copolymer polystyrene-block-poly(n-butylacrylate)-block-poly(γ-methacryloxypropyltrimethoxysilane) (PS-b-PnBA-b-PMPS) with different PnBA block length were synthesized by atom transfer radical polymerization (ATRP), in which PS was a ‘hard’ block and PnBA was a ‘soft’ block. The interfacial crystallization behaviors of glass fiber/polypropylene systems modified with different coupling agents MPS, PS-b-PMPS, and PS-b-PnBA-b-PMPS were investigated on different crystallization conditions. Transcrystallinity could not be induced on non-isothermal crystallization or without maleic anhydride (10%) in polypropylene, but it appeared when glass fibers were treated with common silane coupling agent γ-methacryloxypropyltrimethoxysilane (MPS) and di-block copolymer coupling agent PS-b-PMPS in 135 °C isothermal crystallization without shear and 150 °C isothermal crystallization with shear. However, it disappeared at the interface when the samples were treated with tri-block copolymer coupling agent (PS-b-PnBA-b-PMPS) either under static or shear-induced condition. It might be that the flexible interlayer formed by the flexible block PnBA of PS-b-PnBA-b-PMPS could relax not only the thermal stress resulted from interface temperature gradient arising from sample cooling for crystallization, but also the shear stress induced by fiber/matrix interface shear.

Influence of polymer structure on adsorption behavior at solid–liquid interface by Monte Carlo simulation

Monte Carlo simulations for the adsorption of polymers including random copolymer, homopolymer, diblock copolymer and two kinds of triblock copolymers, respectively, in nonselective solvent at solid–liquid interface have been performed on a simple lattice model. The effect of polymer structure on adsorption properties was examined. In simulations, all polymeric molecules are modeled as self-avoiding linear chains composed of two segments A and B while A is attractive to the surface and B is non-attractive. It was found that for all polymers, the size distribution of various configurations is determined by the linked sequence of segments and the interaction energy between segment and surface. The results of simulation show that the adsorbed amount always increases with increasing bulk concentration but the adsorption layer thickness is mostly dependent on the adsorption energy at a fixed fraction of segments A. On the other hand, diblock copolymer has always the highest surface coverage and adsorbed amount, while random copolymers and homopolymers give generally the smallest surface coverage and adsorbed amount. It is shown that the sequence of polymer chains, i.e. molecular structure, is the most important factor in affecting adsorption properties at the same composition and interaction between segment and surface. The results also show that the adsorption behavior of random copolymers is remarkably different from that of block copolymers, but acting like homopolymer.

Influence of block lengths and symmetries of block copolymers on phase behavior of polymer A/polymer B/block copolymer ternary blends

Monte Carlo simulations were used to investigate the compatibilizing effects of diblock copolymers in A/B/A–B diblock copolymer ternary blends and triblock copolymers in A/B/triblock copolymer ternary blends, respectively. The volume fraction of homopolymer A was 19% and was the dispersed phase. The simulation results show that diblock copolymers with longer A-blocks are more efficient as compatibilizers, and symmetric triblock copolymers with a shorter middle block length are easily able to bridge each other through the association of the end blocks. This kind of triblock copolymers have relatively high ability to retard phase separation as compatibilizers.