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Four hydroxyl-terminated poly(isoprene-b-styrene) diblock copolymers with comparable molecular weights and compositions (equivalent volume fractions of polyisoprene and polystyrene) but different polystyrene block polydispersity indices (Mw/Mn=1.06,1.16,1.31,1.44) were synthesized by anionic polymerization using either sec-butyllithium or the functional organolithium 3-triisopropylsilyloxy-1-propyllithium. Poly(ethylene oxide) (PEO) blocks were grown from the end of each of these parent diblocks to yield four series of poly(isoprene-b-styrene-b-ethylene oxide) (ISO) triblock terpolymers that were used to interrogate the effects of varying the polydispersity of the middle bridged polystyrene block. In addition to the neat triblock samples, 13 multicomponent blends were prepared at four different compositions from the ISO materials containing a polystyrene segment with Mw/Mn=1.06; these blends were used to probe the effects of increasing the polydispersity of the terminal PEO block. The melt-phase behavior of all samples was characterized using small-angle X-ray scattering and dynamic mechanical spectroscopy. Numerous polydispersity-driven morphological transitions are reported, including transitions from lamellae to core-shell gyroid, from core-shell gyroid to hexagonally packed cylinders, and from network morphologies [either O70 (the orthorhombic Fddd network) or core-shell gyroid] to lamellae. Domain periodicities and order-disorder transition temperatures also vary with block polydispersities. Self-consistent field theory calculations were performed to supplement the experimental investigations and help elucidate the molecular factors underlying the polydispersity effects. The consequences of varying the polydispersity of the terminal PEO block are comparable to the polydispersity effects previously reported in AB diblock copolymers. Namely, domain periodicities increase with increasing polydispersity and domain interfaces tend to curve toward polydisperse blocks. The changes in phase behavior that are associated with variations in the polydispersity of the middle bridged polystyrene block, however, are not analogous to those reported in AB diblock copolymers, as increases in this middle block polydispersity are not always accompanied by (i) increased domain periodicities and (ii) a tendency for domain interfaces to curve toward the polydisperse domain. These results highlight the utility of polydispersity as a tool to tune the phase behavior of ABC block terpolymers. [ABSTRACT FROM AUTHOR]

Unsolvated block copolymers and surfactant solutions are 'soft materials' that share a common set of ordered microstructures. A set of polyethyleneoxide-polyethylethylene PEO-PEE) block copolymers that are chemically similar to the well-known alkane-oxyethylene (CnEOm) nonionic surfactants was synthesized here. The general phase behavior in these materials resembles that of both higher molecular weight block copolymers and lower molecular weight nonionic surfactant solutions. Two of the block copolymers exhibited thermally induced order-order transitions and were studied in detail by smallangle scaftering. The fundamental microstructural spacing was determined to be a crucial parameter in these transitions. Transitions from one ordered state to another occur only when the lattice spacing is nearly matched. These materials highlight the importance of epitaxy and molecular conformation in the phase tranqformations of soft material., Amphiphilic molecules such as surfactants, phospholipids, and ionic soaps self-assemble into micelles in dilute aqueous solution because of the hydrophobic effect. As the concentration of the amphiphile increases, thermodynamically stable [...]

Several studies are conducted to explain the mechanisms involved in the stereoselective, as well as the controlled polymerization taking place in the racemic lactide. The application of the approach for the polymerization of various other cyclic esters is also analyzed.

Block polymers containing polylactide (PLA) are prepared as the sacrificial component and perfectly linear polyethylene (LPE) as the matrix phase by using a combination of ring-opening polymerizations. Tensile testing has confirmed the mechanical robustness of the nanoporous samples and the treatment with concentrated strong acids has shown the outstanding chemical resistance of the nanoporous LPE samples.

A ring-closing metathesis was used to prepare the diene 3-methylenecyclopentene from the naturally occurring monoterpene myrcene and Grubbs second generation catalyst. A detailed studies on radical, anionic, and cationic polymerizations of the diene 3-methylenecyclopentene and semicrystalline state of samples of 1,4-poly-diene 3-methylenecyclopentene is also described.

Glycine nanocrystals, grown in aligned nanometer-scale cylindrical pores of nanoporous polystyrene-poly(dimethyl acrylamide) monoliths by evaporation of imbibed aqueous solutions, have adopted preferred orientations with their fast-growth axes aligned parallel with the pore direction. The studies have shown that the [beta]-glycine nanocrystals are formed by homogeneous nucleation, with minimal influence of the pore walls on orientation.

The preparation and synthesis of the optically transparent, amphiphilic networks that are based on the blends of perfluoropolyethers (PFPE) and poly(ethylene glycol) (PEG) are described. The analysis shows that various nanoscopic to macroscopic phase-separated materials can be easily achieved from these materials.

The synthesis and polymerization of a bifunctional cyclic ester derived from lactide is used to increase the strength of polylactide. GrubbsE catalyst was also used to for ring-opening metathesis polymerization.

Polymerization-induced phase separation (PIPS) and a doubly reactive block copolymer are combined to give nanoporous membranes with a percolating pore structure and significant mechanical strength. These membranes are used as high surface area catalysts supports, size selective membranes and nanomaterial templates.

The syntheses, characterization, [epsilon]-caprolactone (CL) polymerization activity and kinetics of two zinc(II) complexes of hindered bis(phenolato)amine complexes are described. The results have supported a monomer-activated mechanism for the polymerization of CL that involves equilibria among various monomeric forms of these complexes.

A study investigates organic nanocrystals embedded in controlled pore glass (CPG) and porous polystyrene (p-PS), to see how the melting properties of the embedded nanocrystals are influenced by both the channel diameter and interfacial interactions with the channel walls. It is demonstrated that melting points decrease with decreasing channel diameter, consistent with the increasing surface-area-to-volume ratio of the crystals.

The regioselective fictionalization of both model and commercial polypropylenes of varying tacticity is conducted by a rhodium-catalyzed fictionalization of the methyl C-H bonds of the polymer with diboron reagents. The synthesis of graft copolymers, such as polypropylene-graft-polycaprolactone, from the hydroxylated isotactic polypropylenes prepared by the rhodium-catalyzed methodology is presented.

An examination of the crystallization of metals, ice and organic solids in porous media, including commercially available controlled pore glass (CPG) with pure dimensions