Materials Literature
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The addition of non-adsorbing polymer to a colloidal suspension induces an interparticle ‘depletion’ attraction whose range and depth can be ‘tuned’ independently by altering the polymer’s molecular weight and concentration respectively. Over the past decade, one particularly simple experimental realization of such a…
Synthetic polymers offer a wealth of opportunities to design responsive materials triggered by external stimuli. Changing the length, chemical composition, architecture, and topology of the chains allows response mechanisms and rates to be easily manipulated; and devices based on the entropy of the chains, surface ene…
Nonlinear viscoelastic properties are reported for composites of fumed silica with various surface treatments and matrices of poly(vinyl acetate) of different molecular weights as well as a copolymer matrix of vinyl acetate and vinyl alcohol. Data above the glass transition temperature are reported here. The increase…
Ferroelectric switching and nanoscale domain dynamics were investigated using atomic force microscopy on monocrystalline $\mathrm{P}\mathrm{b}\mathrm{(}\mathrm{Z}{\mathrm{r}}_{\mathrm{0.2}}\mathrm{T}{\mathrm{i}}_{\mathrm{0.8}}\mathrm{)}{\mathrm{O}}_{\mathrm{3}}$ thin films. Measurements of domain size versus writing t…
pi-Conjugated polymers that are electrochemically cycled in ionic liquids have enhanced lifetimes without failure (up to 1 million cycles) and fast cycle switching speeds (100 ms). We report results for electrochemical mechanical actuators, electrochromic windows, and numeric displays made from three types of pi-conju…
The correlated Pariser–Parr–Pople model Hamiltonian for interacting π-electrons is employed for calculating frequency dependent linear polarizability as well as first and second hyperpolarizabilities of linear chain phosphazenes (–P=N–)x (x=3–6). The model parameters for phosphorus and nitrogen are obtained by compari…
We have carried out NPT molecular dynamics simulations of isolated ellipsoids in a glass forming binary mixture to gain insight into the nature of orientational relaxation (OR) in a viscous liquid. At high pressures when the liquid is highly viscous, the OR is found to occur mainly via correlated hopping, sometimes in…
In the framework of the two-step model of Auger decay the orientation of the krypton ${3d}^{\ensuremath{-}1}$ and xenon ${4d}^{\ensuremath{-}1}$ primary hole states has been determined as a function of photon energy. This was achieved by carrying out spin-polarization measurements of the Kr ${M}_{4,5}{N}_{2,3}{N}_{2,3…
We have studied the electrical conductivity of well–aligned samples of hexahexylthiotriphenylene (HHTT) and hexapentyloxyanthraquinone (HPA) in the pure, as well as doped, states. The former compound was doped with 0.62 mol % by weight of the electron acceptor, trinitrofluorenone (TNF), the latter with 0.60 mol % by w…
The magnetic properties of the molecular cluster ${\mathrm{Mn}}_{12}\mathrm{Ac}$ are due to the four ${\mathrm{Mn}}^{3+}$ ions that have spins $S=3/2$ and the eight ${\mathrm{Mn}}^{4+}$ ions with spins $S=2.$ These spins are coupled by an exchange mechanism. We determine the four exchange couplings assuming a Heisenbe…
A novel soluble aryl amide-bridged ladderlike polymethylsiloxane (A-LPMS) was synthesized by stepwise coupling polymerization on the basis of amido H-bonding self-assembling template from monomer N,N'-bis(3-methyldiethoxylsilylpropyl)-[4,4'-oxybis(benzyl amide)]. The monomer was prepared in a high yield by the hydrosi…
The mechanism for isotopic exchange by proton hopping and subsequent reorientation of H2O molecules in vapor-deposited, 0.1 mol % 2-naphthol containing amorphous solid water [M. Fischer and J. P. Devlin, J. Phys. Chem. 99, 11584 (1995)] has been reconsidered and an alternative mechanism in terms of diffusion controlle…
A new mechanism of electron paramagnetic resonance in spherical zinc-blende semiconductor nanocrystals, based on the extended orbital motion of electrons in the entire nanocrystal, is presented. Quantum confinement plays a crucial role in making the resonance signal observable. The mechanism remains operative in nanoc…
A Zr-promoted Pd/HZSM-5 catalyst, prepared by an impregnation method, was found to possess high catalytic activity as well as thermal and hydrothermal stability for low-temperature methane combustion.
Thin films of poly(styrene-b-methyl methacrylate) diblock copolymers above the bulk order-disorder transition temperature, within a certain thickness range, are structurally unstable on SiO(x)/Si substrates. They dewet autophobically, forming droplets on a self-assembled brush. We investigated the late-stage evolution…
This contribution reports the first synthesis of conducting polymers (CPs), specifically, polyaniline (PAn) and polypyrrole (PPy), in supercritical carbon dioxide (scCO2). CPs synthesized electrochemically in scCO2 were characterized with cyclic voltammetry (CV), four-point probe conductivity, scanning electron micros…
We present a theoretical study of a new class of polymer materials of much recent experimental interest: polymer networks bearing dendritic wedges in the middle of long network strands. We focus on the Rouse dynamics of such cross-linked polymers and perform our study in three steps, considering first single dendritic…
Two analytical procedures based on the time-dependent Hartree–Fock (TDHF) scheme are elaborated to evaluate the first derivatives of the dynamic first hyperpolarizability with respect to atomic Cartesian coordinates. In the first scheme, the mixed third-order TDHF equations are solved iteratively to obtain the third d…
This work presents the synthesis and characterization of SiO 2:metal (Ni, Co, Ag, and Fe) nanocomposites processed by the polymerizable complex method. The polymeric precursor solutions obtained were characterized by means of FT-Raman and 13 C NMR spectroscopy. The results show the formation of a hybrid polymer with c…
We report on a Monte Carlo study of the liquid crystal phases of two model fluids of linear elongated molecules: (a) hard spherocylinders with an attractive square-well (SWSC) and (b) purely repulsive soft spherocylinders (SRS), in both cases for a length-to-breadth ratio L*=5. Monte Carlo simulations in the isotherma…