Polystyrene-poly Methyl Methacrylate Block Copolymer Research Articles

Blockcopolymer Self-Assembly Directed by Photochemically Attached Polymer Surface Layer

The microdomain structure of polystyrene-polymethylmethacrylate block copolymer (PS-b-PMMA) can be directed by a photochemically attached polymer surface layer. The photochemical attachment of the neutralization polymer on the silicon surface is a convenient and effective technique for interfacial energy control to provide the directed self-assembly of block copolymer. The perpendicular microdomain structure of PS-b-PMMA was formed on the polymer surface layer and the directed microdomain orientation of PS-b-PMMA was obtained on the polymer surface pattern.

Polystyrene-Polymethylmethacrylate Block Copolymers for Lithographically Assisted Bottom-Up Assembly of Nanostructures

Polystyrene-polymethylmethacrylate (PS-PMMA) block copolymers are well known to exhibit microphase separation to form a series of regular structures with local periodic arrangements of the blocks. By developing films of PS-PMMA within topographically patterned silicon (100) substrates (with photolithographically defined rectangular channels of depth 60 nm and widths 166 – 433 nm) these irregular arrangements form highly periodic structures where the features are parallel to the side walls of the channels. However, the use of silicon substrates leads to problems in processing of these films. PS-PMMA does not wet the surface, and this results in island formation on flat substrates. On channel etched substrates this phenomena ensures that the thickness of the films is irregular and poorly defined alignment is seen. Detailed considerations of this polymer system suggest that feature sizes below 25 nm are not realisable. The results suggest other copolymer systems should be studied.

“Living” Radical Polymerization of Styrene Using Diphenylmethane Diisocyanate-Based Polyurethane Iniferter

Polyurethane iniferter, synthesized from diphenylmethane diisocy-anate and 1,1,2,2-tetraphenyl-1,2-ethanediol, was used to polymerize styrene. The increase of number-average molecular weight of the polystyrene while increasing both conversion and polymerization time prove that the polymerization of styrene using polyurethane iniferter is through a “living” radical mechanism. Postpolymerization of polystyrene in the presence of styrene and methyl methacrylate yielded high molecular weight polystyrene and polystyrene-polymethyl methacrylate block copolymers respectively.

Note: Selectivity and Permeability of Microporous Block Copolymer Membranes

Abstract : A selective solvent was used to develop a uniform microporous structure in a polystyrene-polymethylmethacrylate block copolymer. Pore diameters in the range of 200-500 angstroms were produced. Gas permeation measurements demonstrated a dramatic, five order of magnitude, increase in permeability coefficient associated with the throughgoing microporous structure. These high-flux membranes retained some selectivity for certain gas pairs as expected for transport based on Knudsen diffusion in the porous materials.... Microporous membranes, Gas separations, Knudsen diffusion, Block copolymers.

Investigation of polystyrene-polymethylmethacrylate block-copolymers by high-efficiency gel-permeation chromatography

Gel-permeation chromatography has been used to investigate PS-PMMA block-copolymers synthesized by free-radical polymerization in the presence of the system polystyrylaluminium-organic peroxide. The effect of the nature of the peroxide component of the initiating system and the concentration of an additionally introduced electron-donor on the molecular and structural properties of the block-copolymers have been established. It has been shown to be possible to regulate the molecular properties of the block-copolymer as a whole and also those of each of the blocks making up the block-copolymer.