Morphologies of ABC triblock terpolymer melts containing poly(cyclohexadiene): effects of conformational asymmetry.

We have synthesized linear ABC triblock terpolymers containing poly(1,3-cyclohexadiene), PCHD, as an end block and characterized their morphologies in the melt. Specifically, we have studied terpolymers containing polystyrene (PS), polybutadiene (PB), and polyisoprene (PI) as the other blocks. Systematically varying the ratio of 1,2- /1,4-microstructures of poly(1,3-cyclohexadiene), we have studied the effects of conformational asymmetry among the three blocks on the morphologies using transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and self-consistent field theory (SCFT) performed with PolySwift++.

Nanostructured block-random copolymers with tunable magnetic properties.

It was recently shown that block copolymers (BCPs) produced room-temperature ferromagnetic materials (RTFMs) due to their nanoscopic ordering and the cylindrical phase yielded the highest coercivity. Here, a series of metal-containing block-random copolymers composed of an alkyl-functionalized homo block (C(16)) and a random block of cobalt complex- (Co) and ferrocene-functionalized (Fe) units was synthesized via ring-opening metathesis polymerization. Taking advantage of the block-random architecture, the influence of dipolar interactions on the magnetic properties of these nanostructured BCP materials was studied by varying the molar ratio of the Co units to the Fe units, while maintaining the cylindrical phase-separated morphology.

Additive-driven assembly of block copolymer-nanoparticle hybrid materials for solution processable floating gate memory.

Floating gate memory devices were fabricated using well-ordered gold nanoparticle/block copolymer hybrid films as the charge trapping layers, SiO(2) as the dielectric layer, and poly(3-hexylthiophene) as the semiconductor layer. The charge trapping layer was prepared via self-assembly. The addition of Au nanoparticles that selectively hydrogen bond with pyridine in a poly(styrene-b-2-vinyl pyridine) block copolymer yields well-ordered hybrid materials at Au nanoparticle loadings up to 40 wt %.

Zwitterionic polymersomes in an ionic liquid: room temperature TEM characterization.

Conventional transmission electron microscopy (TEM) was utilized to characterize vesicles formed by the spontaneous self-assembly of a novel zwitterionic block copolymer in the ionic liquid (2-hydroxyethyl)dimethylammonium methanesulfonate as well as in 0.1 M phosphate buffered saline (PBS). This block copolymer was synthesized via ring-opening metathesis polymerization (ROMP) of a norbornene-based sulfobetaine, followed by its end-functionalization with polystyrene to generate the necessary amphiphilic structure.

Nanoparticle-driven assembly of block copolymers: a simple route to ordered hybrid materials.

The addition of nanoparticles that selectively hydrogen bond with one of the segments of a block copolymer is shown to induce order in otherwise disordered systems. This enables the fabrication of well-ordered hybrid materials with spherical, cylindrical, or lamellar domains at particle loadings of more than 40%, as evidenced by TEM and SAXS. The approach described is simple and applicable to a wide range of nanoparticles and block copolymers, and it lays the groundwork for the design of cooperatively assembled functional devices.

Wet-spinning of osmotically stressed silk fibroin.

Based on the phase diagram constructed for water-silk fibroin-LiBr using the osmotic stress method, wet-spinning of osmotically stressed, regenerated Bombyx mori silk fibroin was performed, without the necessity of using expensive or toxic organic solvents. The osmotic stress was applied to prestructure the regenerated silk fibroin molecule from its original random coil state to a more oriented state, manipulating the phase of the silk solution in the phase diagram before the start of spinning. Various starting points for spinning were selected from the phase diagram to evaluate the spinning performance and also physical properties of fibers produced.

The effect of molecular architecture on the grain growth kinetics of AnBn star block copolymers.

To investigate the effect of molecular architecture on the grain growth kinetics of star block copolymers, a series of AnBn miktoarm star block copolymers with different numbers of arms (n = 1, 2, 4 and 16) was studied. Across this entire series of materials, all the A arms are polystyrene (PS) blocks from the same anionically synthesized batch, and thus all the A arms are identical. Likewise, all the B arms are polyisoprene (PI) blocks from the same anionically synthesized batch, and thus all the B arms are identical.

Phase behavior and hydration of silk fibroin.

The osmotic stress method was applied to study the thermodynamics of supramolecular self-assembly phenomena in crystallizable segments of Bombyx mori silkworm silk fibroin. By controlling compositions and phases of silk fibroin solution, the method provided a means for the direct investigation of microscopic and thermodynamic details of these intermolecular interactions in aqueous media. It is apparent that as osmotic pressure increases, silk fibroin molecules are crowded together to form silk I structure and then with further increase in osmotic pressure become an antiparallel beta-sheet structure, silk II.