Materials Literature
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The wetting behavior of hybrid isotropic/smectic block copolymers is examined. For symmetric diblocks, the generic parallel ordering of the lamellae is suppressed, and the copolymer wets the surface with the lamellae perpendicular to the surface. The parallel ordering, however, can be restored in asymmetric lamellar d…
The electron paramagnetic resonance (EPR) signal in the mixed valence perovskite ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3+y}$ was investigated in the paramagnetic regime for ${}^{16}$O and ${}^{18}$O isotope substituted compounds. The characteristic differences observed in EPR intensity and…
We show that many two dimensional domain patterns observed in Monte Carlo simulations can be obtained from the many soliton solutions of the imaginary time Sine Gordon equation. This opens the door to analytic physical understanding of the micromagnetics in ultra-thin films.
The kinetics of formation and the structure of an adsorbed layer formed by homopolymer chains irreversibly adsorbed onto a flat wall are studied by Monto Carlo simulation using the bond fluctuation model. The rapid initial adsorption is followed by slow kinetics at later times. The surface coverage can be described by…
We consider the steady-state competition between perfectly absorbing sinks distributed uniformly in a spherical region. An equation for the coarse-grained concentration of diffusing particles inside the region is derived following the renormalization group approach. The total flux of diffusing particles, their coarse-…
Using redundant inverse-power distance coordinates we present a series of optimizations on randomly generated argon clusters containing 12, 24, and 48 argon atoms. Our results clearly show that inverse distance coordinates perform significantly better for optimizing the geometries of atomic clusters than either Cartes…
For atoms or molecules of D∞h or higher symmetry, this work gives equations for the long-range, collision-induced changes in the first (Δβ) and second (Δγ) hyperpolarizabilities, complete to order R−7 in the intermolecular separation R for Δβ, and order R−6 for Δγ. The results include nonlinear dipole-induced-dipole (…
The shear viscosity of water at 303.15 K is calculated for the extended simple point charge (SPC/E) model of Berendsen et al. [J. Phys. Chem. 91, 6269 (1987)] using both equilibrium and nonequilibrium molecular dynamics (NEMD) methods. Reciprocal space sums to handle long-range electrostatic forces in a noncubic simul…
We have devised a reversible set of nonequilibrium molecular dynamics equations of motion to study viscous flow under an applied shear field utilizing a new profile unbiased thermostat (PUT). Based on a modification of the original equations presented by Evans and Morriss [Phys. Rev. Lett. 56, 2172 (1986)], we have ex…
Polymer chains attached by one end to an impenetrable surface at high coverage exemplify a tethered layer of mesoscopic dimensions. At equilibrium, thermal fluctuations of the segment density profile of the brushlike layer reflect the tethered chain dynamics; the probing of these fluctuations by evanescent-wave dynami…
A pressure and temperature dependent Raman study of the vibrational and spin dynamics in CuGeO3 is presented. A new low temperature, high pressure phase has been identified, and a pressure-temperature phase-diagram is proposed for CuGeO3. The pressure dependence of the effective exchange interaction, of the spin-Peier…
Interpenetrating polymer networks (IPNs) with a controlled degree of microphase separation were synthesized from a poly(ether urethane) (PUR) and poly(ethyl methacrylate) (PEMA). The influence of the crosslink density of both networks was investigated in the 70:30 PUR/PEMA IPN. The extent of damping was evaluated by d…
Thermal conductivity and mechanical properties such as tensile strength, elongation at break, and modulus of elasticity of aluminum powder-filled high-density polyethylene composites are investigated experimentally in the range of filler content 0–33% by volume for thermal conductivity and 0–50% by volume for mechanic…
Plasma polymerization is a useful method for depositing thin films on substrates. The films formed are cross-linked, and their character depends on the plasma polymerization process conditions. The influence of power and monomer flow rate on the character of plasma-polymerized hexamethyldisiloxane (PPHMDSO) was invest…
Aqueous cationomeric polyurethanes (ACPU) were synthesized by a multistep reaction process. The alipathic diisocyanate, e.g., hexamethylene diisocyanate (HDI), was reacted with polyol, e.g., polypropylene glycol (PPG400) to form a prepolymer and it was chain-extended by reacting it with N-methyldietanolamine (N-MEDA).…
Poly(vinyl alcohol) (PVA) is soluble only in water and so some important derivatives like esters cannot be prepared from PVA. The 100% conversion of PVA to acetal is also elusive as there is strong intermolecular and intramolecular hydrogen bonding. However, PVA can be dissolved in a nonaqueous medium in the presence…
The most widely accepted method for determining Hansen's three-dimensional solubility parameters (3DSP) for crosslinked polymers entails graphically estimating the center of a spherical region in 3DSP-coordinate space whose boundaries are defined in terms of the extent of swelling by solvents whose 3DSP values are kno…
The cubic-to-orthorhombic structural transition occurring in CsH at a pressure of about 17 GPa is studied by ab initio calculations. The relative stability of the competing structures and the transition pressure are correctly predicted. We show that this pressure-induced first-order transition is intimately related to…
Thermal conductivity and mechanical properties such as tensile strength, elongation at break, and modulus of elasticity of aluminum powder-filled high-density polyethylene composites are investigated experimentally in the range of filler content 0–33% by volume for thermal conductivity and 0–50% by volume for mechanic…
The existence of anharmonic localization of lattice vibrations in a perfect 3-D diatomic ionic crystal is established for the rigid-ion model by molecular dynamics simulations. For a realistic set of NaI potential parameters, an intrinsic localized gap mode vibrating in the [111] direction is observed for fcc and zinc…