Selective and Sequential Re‐Assembly of Patterned Block Copolymer Thin Film for Fabricating Polymeric,Inorganic, and Their Composite Nanostructured Arrays

We report that the nanostructures of poly(styrene‐block‐4‐vinylpyridine) block copolymer (PS‐b‐P4VP) thin film on a wafer substrate can be re‐assembled by sequential vapor treatment using selected solvents. Metal or other inorganic nanoparticles that were randomly pre‐loaded inside or on the surface of PS‐b‐P4VP thin film could be pulled to the rim of PS and P4VP along with the movements of PS and P4VP blocks during the treatment. As a result, the patterned polymeric or inorganic/polymer composite nanoisland and nanoring arrays were fabricated.

     

Orienting the Demixion of a Diblock‐copolymer Using 193 nm Interferometric Lithography for the Controlled Deposition of Nanoparticles

DUV interferometric lithography and diblock copolymer self‐organization have successfully been combined to provide a simple and highly collective nanopatterning technique enabling the organization of nanoparticles over several orders of magnitude, from nanometre to millimetre. The nanostructural changes at the surface of the polymer film after thermal annealing have been monitored by AFM and the process parameters optimized for obtaining a long‐range organization of the lamellar domains. In particular, the impact of the annealing conditions and geometric parameters of the substrate patterns have been investigated. The nanopatterns resulting from the lamellar demixion of (PS‐b‐MMA) were used for a controlled deposition of nanoparticles. The affinity of the hydrophobic particles for the PS block was demonstrated, opening new doors towards the preparation of high‐density arrays of nanoparticles with potential applications in data storage.

     

Step‐Growth Radical Addition‐Coupling Polymerization (RACP) for Synthesis of Alternating Copolymers

We report a new type of step‐growth radical addition‐coupling polymerization (RACP) involving consecutive addition of carbon‐centered radical derived from α,α′‐dibromo dibasic ester to NO double bond of C‐nitroso compound followed by cross‐coupling of carbon‐centered radical and in situ formed nitroxyl radical, which produces alternating copolymers with high molecular weight and unimodal molecular weight distribution from saturated and unsaturated monomers.

     

Thermoresponsive Block Copolymer–Protein Conjugates Prepared by Grafting‐from via RAFT Polymerization

Well‐defined “smart” block copolymer–protein conjugates were prepared by two consecutive “grafting‐from” reactions via reversible addition–fragmentation chain transfer (RAFT) polymerization. The initiating portion (R‐group) of the RAFT agent was anchored to a model protein such that the thiocarbonylthio moiety was readily accessible for chain transfer with propagating chains in solution. Well‐defined polymer‐protein conjugates of poly(N‐isopropylacrylamide) (PNIPAM) and bovine serum albumin (BSA) were prepared at room temperature in aqueous media. The retained trithiocarbonate moiety on the free end group of the immobilized polymer allowed the homopolymer conjugate to be extended by polymerization of N,N‐dimethylacrylamide. Polyacrylamide gel electrophoresis, size exclusion chromatography, and NMR spectroscopy confirmed the synthesis of the various conjugates and revealed that the polymerizations were well controlled. As expected, the resulting block copolymer–protein conjugates demonstrated thermoresponsive behavior due to the temperature‐sensitivity of the PNIPAM block, as evidenced by turbidity measurements and dynamic light scattering analysis.

     

Dissipative Particle Dynamics Simulation of Microscopic Properties in Diblock Copolymer Films

利用耗散粒子动力学模拟方法研究了两嵌段共聚高分子薄膜中的一些微观性质. 结果表明：薄膜中共聚高分子链的均方根末端距2_e>^1/2、均方根回旋半径2_g>^1/2与薄膜厚度l、不同粒子间的相互作用强度a_ij、粒子与薄膜边界间的排斥作用强度a_pb均呈线性关系,而均方键长与a_ij、a_pb呈线性关系,随l增加则呈现出波浪形趋势. 2_e>^1/2与2_g>^1/2的变化趋势可以相互对应. 任一组分在薄膜中的密度分布可以通过其与薄膜边界间的相互作用来有效控制与调节.     

Redox properties and radical anions of fluorinated 2,1,3‐benzothia(selena)diazoles and related compounds

In comparison with 2,1,3‐benzothia(selena)diazoles, electrochemical oxidation and reduction of their 4,5,6,7‐tetrafluoro derivatives and a number of related compounds were studied by cyclic voltammetry. For nine examples of this class, the first reduction peaks are reversible and corresponding radical anions (RAs) are long‐lived at 295 K in MeCN and especially in DMF. The oxidation peaks were irreversible and corresponding radical cations were not observed. Electrochemically generated RAs were characterized by EPR measurements and DFT calculations at the UB3LYP/6‐31+G(d) level. The spin density distribution in the RAs is analyzed in connection with effects of S substitution by Se and/or H by F. The prospects of the studied RAs in the design and synthesis of magnetically active materials are discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

Spatial arrangement of metal nanoparticles supported by porous polymer substrates studied by transmission electron microtomography

Fine metal particles (nanoparticles) stabilized on porous (polymeric) substrates can be considered as a model system of a high-performance catalyst. In the present study, the substrate was made using the periodic microphase-separated structure of a block copolymer as the template, and the Pd nanoparticles were formed inside the porous material by reduction of the Pd2+ ions with 1-propanol as the reductant. The three-dimensional morphology of such a polymer-Pd hybrid material was studied by transmission electron microtomography. The characteristic structural parameters of the hybrid, e.g., the penetration of the Pd nanoparticles into the polymer substrate, number density of the Pd nanoparticles, and size distribution of the Pd nanoparticles, were measured for the first time.     

Synthesis of fluorinated chitin derivatives via enzymatic polymerization

Synthesis of fluorinated chitin derivatives has been achieved using chitinase from Bacillus sp. as a catalyst. 6'-Fluoro- (1a), 6-fluoro- (1b) and 6,6'-difluoro- (1c) chitobiose oxazoline derivatives were newly prepared as TSAS monomers for chitinase. Ring-opening polyaddition of these monomers proceeded effectively at pH 8.0-9.0 and 30-40 degrees C, giving rise to alternatingly 6-fluorinated chitin derivatives (2a and 2b) from 1a and 1b, and fully 6-fluorinated chitin derivative (2c) from 1c under total control of regioselectivity and stereochemistry. XRD measurements revealed that polysaccharides 2a and 2b had crystalline structures similar to that of alpha-chitin. [reaction: see text]     

A new method of non-contact gauge block calibration using a fringe-counting technique: I. Theoretical basis

A new non-contact interference method for gauge block or length bar calibration is presented. A central interference fringe of polychromatic light is used for the determination of the end surface position of the measured artefact. Distances referring to these positions are measured using a fringe-counting technique, with a wavelength-stabilized laser interferometer. Absolute and comparative measurement methods are proposed. A new technique for central interference fringe detection and identification is discussed.