Materials Literature
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Poly(carboxylic acid)s have been used as crosslinking agents for wood pulp cellulose to increase the wet strength of paper. In this research, we evaluated the effects of two multifunctional carboxylic acids, i.e., 1,2,3,4-butanetetracarboxylic acid (BTCA) and poly(maleic acid) (PMA), on the wet strength retention, dim…
In situ reinforced binary and ternary polymer/polymer composites are obtained by the melt blending of poly(ethylene terephthalate) (PET), polyamide-6 (PA-6), and polyamide-66 (PA-66) in an extruder in the presence of a catalyst, followed by drawing of the extrudate and annealing of the drawn blends. The blends were st…
Vinyl-substituted silphenylene siloxane elastomers (VSPSEs) with variable vinyl content were synthesized using the disilanol−diaminosilane polycondensation method. High molecular weight elastomers were obtained by using carefully purified monomers. The polymers were characterized by gel permeation chromatography, diff…
The polymerization kinetics of zirconium propoxide (and in a few cases of titanium butoxide) were studied in various conditions by following the diffusion of an electroactive probe attached to the metal center. Two different probes were considered, implying the complexation of the metal alkoxides with bidentate ligand…
The temperature−concentration phase diagrams have been established for sPMMA gels prepared from toluene, chlorobenzene, and bromobenzene. In these three solvents polymer−solvent compounds are formed: one compound in toluene (two toluene molecules/three monomers) and two compounds in bromobenzene and chlorobenzene (two…
The adsorption of equimolar binary Lennard-Jones gas mixtures into single-walled carbon nanotubes is investigated using grand canonical Monte Carlo simulations. For mixtures whose species have different molecular diameters, the larger energetically favored species is adsorbed at higher temperatures. However, at lower…
The surface composition of binary blends of isotactic and syndiotactic poly(methyl methacrylate) (i-PMMA/s-PMMA blends) solvent-cast in the form of films on glass substrates has been studied by attenuated total reflection Fourier transform (ATR-FTIR) spectroscopy and contact angle measurements. We find that the syndio…
A method was developed to measure the area-averaged mean and the Gaussian curvatures from three-dimensional (3D) digital images of the interface of complicated bicontinuous structures. This method involves measurement of areas of surfaces that are parallel to the interface as a function of displacement from it. The ap…
The longitudinal relaxation time constants ( T 1 ) of the protons in a series of dendrimers that alternatively had paramagnetic ([Fe 4 S 4 (SR) 4 ] 2-, R = dendron) and diamagnetic (tetraphenylmethane) cores were compared. The T 1 values of the phenyl and benzyl protons in the paramagnetic core dendrimers were attenua…
A series of dimeric through octameric (1→5) amide-linked sialooligomers were prepared using solid-phase peptide methods on Rink resin with Fmoc protecting group chemistry. The oligomers were conjugated to ε-amino caproic acid in order to model membrane-bound conformations. The secondary structure of the oliogomers was…
We consider the variation in miscibility during a polycondensation reaction which forms a random multiblock copolymer. Taking a “Markov chain” model for the reacting polymer system, we apply the random phase approximation and calculate the spinodal as a function of degree of reaction. In order to achieve this, we deve…
An attempt has been made to understand the mechanism of ionic conductivity in polyphosphazene−salt complexes by the synthesis and study of systems with crown ether side groups and salts with different cations. Amorphous phosphazene polymers, bearing either (12-crown-4)-methoxy, (15-crown-5)-methoxy, or (18-crown-6)-me…
A hyperbranched polyfluorinated benzyl ether polymer was prepared from the A 2 B monomer 3,5-bis[(pentafluorobenzyl)oxy]benzyl alcohol. The polymerization was based upon deprotonation of the benzylic alcohol (B), followed by nucleophilic substitution of the p -fluorines of the two pentafluorophenyl (A) groups to form…
Histogram reweighting Monte Carlo simulations were used to obtain polymer/solvent phase diagrams for lattice homopolymers of chain lengths up to r = 1000 monomers. The simulation technique was based on performing a series of grand canonical Monte Carlo calculations for a small number of state points and combining the…
We comment some recent unexpected experimental results on proton/deuteron deep inelastic scattering off water molecules in H2O-D2O mixtures (C.A. Chatzidimitrou-Dreismann et al. Phys. Rev. Lett. 79, 2839 (1997)) where a strong dependence of the ratio of proton/deuteron cross sections on the composition of the mixture…
A Fourier transform infrared (FT-IR) spectrometer equipped with a microscopic accessory was used to monitor the cellulose crystalline structure at each developmental stage of coniferous tracheid cell wall formation. The spectra showed that the cellulose in the primary cell wall was rich in the metastable I α crystalli…
Use of amphiphilic triblock copolymers to direct the organization of polymerizing silica species has resulted in the preparation of well-ordered hexagonal mesoporous silica structures (SBA-15) with uniform pore sizes up to approximately 300 angstroms. The SBA-15 materials are synthesized in acidic media to produce hig…
Density and viscosity of 0.25[xKSCN + (1 − x )NaSCN] + 0.75CH 3 CONH 2 melt systems were measured as functions of temperature (293.15 ≤ T /K ≤ 343.15) and mole fraction, x = 0.0 to 1.0. The temperature dependence of viscosity has been analyzed by using the Vogel−Tammann−Fulcher (VTF) equation. Molar volumes and intrin…
Aerial oxidation of Mn(II)/ptt(3)(-) (ptt(3)(-) = propane-1,2,3-trithiolate) mixtures gives [Mn(2)(pttd)(2)](2)(-), where pttd(4)(-) is the mono(disulfide) of ptt(3)(-). (NEt(3)Bz)(2)[Mn(2)(pttd)(2)] (2) crystallizes in space group P2(1)/c with (at -158 degrees C) a = 11.540(2) Å, b = 12.115(2) Å, c = 17.478(4) Å, bet…
The interfacial properties of a three-component, two-phase A/B:C blend are investigated to understand the effect of the A and B chain lengths on the interfacial excess of B, z B *, the interfacial tension, γ ABC, and the interfacial width, w ABC . The A/B:C components are polystyrene/poly( d 8 -styrene- co -4-bromosty…