New polymer synthesis by nitroxide mediated living radical polymerizations.

http://wwwcourses.sens.buffalo.edu/ce435/Riess03.pdf

Micellization of block copolymers

A mean-field phase diagram for conformationally symmetric diblock melts using the standard Gaussian polymer model is presented. Our calculation, which traverses the weak- to strong-segregation regimes, is free of traditional approximations. Regions of stability are determined for disordered (DIS) melts and for ordered structures including lamellae (L), hexagonally packed cylinders (H), body-centered cubic spheres (QIm3m), close-packed spheres (CPS), and the bicontinuous cubic network with Ia3d symmetry (QIa3d). The CPS phase exists in narrow regions along the order−disorder transition for χN ≥ 17.67. Results suggest that the QIa3d phase is not stable above χN ∼ 60. Along the L/QIa3d phase boundaries, a hexagonally perforated lamellar (HPL) phase is found to be nearly stable. Our results for the bicontinuous Pn3m cubic (QPn3m) phase, known as the OBDD, indicate that it is an unstable structure in diblock melts. Earlier approximation schemes used to examine mean-field behavior are reviewed, and compa...

Unifying Weak- and Strong-Segregation Block Copolymer Theories

The structural and mechanical properties of gels formed from biopolymers are discussed both in terms of the techniques used to characterise these systems, and in terms of the systems themselves The techniques included are spectroscopic, chiroptical and scattering methods, optical and electron microscopy, thermodynamic and kinetic methods and rheological characterisation The systems considered are presented in order of increasing complexity of secondary, tertiary and quaternary structure, starting with gels which arise from essentially ‘disordered’ biopolymers via formation of ‘quasicrystalline’ junction zones (eg gelatin, carrageenans, agarose, alginates etc), and extending to networks derived from globular and rod-like species (fibrin, globular proteins, caseins, myosin) by a variety of crosslinking mechanisms Throughout the text, efforts are made to pursue the link (both from experiment and from theory) between the structural methods and mechanical measurements As far as we are aware this is the first major Review of this area since that of J D Ferry in 1948 — The interest shown by polymer physicists in more complex biochemical systems, and the multi-disciplinary approaches now being applied in this area, make the format adopted here, in our opinion, the most logical and appropriate

Structural and mechanical properties of biopolymer gels

Directing the self-assembly of block copolymers

Nanostructured thermoset blends of bisphenol A-type epoxy resin (ER) and amphiphilic poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (PEO−PPO−PEO) triblock copolymers were successfully prepared. Two samples of PEO−PPO−PEO triblock copolymer with different ethylene oxide (EO) contents, denoted as EO30 with 30 wt % EO content and EO80 with 80 wt % EO content, were used to form the self-organized thermoset blends of varying compositions using 4,4‘-methylenedianiline (MDA) as curing agent. The phase behavior, crystallization, and morphology were investigated by differential scanning calorimetry (DSC), transmission electron microscopy (TEM), atomic force microscopy (AFM), and small-angle X-ray scattering (SAXS). It was found that macroscopic phase separation took place in the MDA-cured ER/EO30 blends containing 60−80 wt % EO30 triblock copolymer. The MDA-cured ER/EO30 blends with EO30 content up to 50 wt % do not show macroscopic phase separation but exhibit nanostructures on the or...

Phase behavior, crystallization, and hierarchical nanostructures in self-organized thermoset blends of epoxy resin and amphiphilic poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) triblock copolymers

Rubber compounds based on butadiene rubber (BR) or styrene—butadiene rubber (SBR) containing organophilic layered silicates were prepared. Organophilic silicates were swollen in a rubber/toluene solution. Matrix—filler reactive bonding was performed by adding bis(triethoxysilylpropyl)-tetrasulfan (TESPT) during swelling. Excellent dispersion of organoclay nanofillers in rubber matrices was demonstrated by transmission electron microscopy (TEM) and atomic force microscopy (AFM) exhibiting intercalated and partially exfoliated silicate layers. Matrix—filler interfacial coupling by TESPT led to reduced strain at break and reduced hysteresis for both organoclay and silica-based vulcanizates as expected for successful matrix filler coupling. Organoclay vulcanizates exhibited enhanced hysteresis when compared to silica compounds. This is related to orientation and sliding of anisotropic silicate layers, as determined by online wide-angle X-ray scattering (WAXS) measurements during cyclic tensile testing.

Rubber Nanocomposites: Morphology and Mechanical Properties of BR and SBR Vulcanizates Reinforced by Organophilic Layered Silicates

Cocontinuous polymer blends: influence of viscosity and elasticity ratios of the constituent polymers on phase inversion

Synthese par deux reactions analogues successives avec la possibilite d'employer une grande variete d'unites mesogenes. Le polymere de depart est un polybutadiene-1,2 prepare par voie anionique: 1ere etape conversion de la double liaison en groupe alcool puis oxydation, 2eme etape les unites mesogenes sont reliees au polyalcool par liaison oxycarbonyl au cholesteryle

Wolfram Gronski

Papers

Phase behavior, crystallization, and hierarchical nanostructures in self-organized thermoset blends of epoxy resin and amphiphilic poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) triblock copolymers

Rubber Nanocomposites: Morphology and Mechanical Properties of BR and SBR Vulcanizates Reinforced by Organophilic Layered Silicates

Cocontinuous polymer blends: influence of viscosity and elasticity ratios of the constituent polymers on phase inversion

LC side chain AB‐block copolymers with an amorphous A‐block and a liquid‐crystalline B‐block

Evidence of nonaffine and inhomogeneous deformation of network chains in strained rubber-elastic networks by deuterium magnetic resonance