A structural study of perfluorosulfonated ionomer (PFSI) solutions in polar solvents such as alcohols, amides, and water using both small-angle X-ray neutron scattering is presented. Contrast variation methods have shown that the molecule particles form dense constant length. The dilute allows one to evidence rodlike structure PFSI solutions. radius cylindrical determined from shape intensities curves. These results are confirmed by analysis asymptotic behavior at large angles Typical values...

The colloidal structure of perfluorinated ionomer solutions in polar solvents which are not able to dissolve the neutral polymer analogue is confirmed studying short pendant chain perfluorosulfonated by small-angle X-ray and neutron scattering. analysis form factor obtained from "dilute" solution spectra combined with asymptotic behavior at large q values indicates existence rodlike shape aggregates. radius found be 17 Å for aqueous solutions. effects nature solvent presence added salt...

Concentrated clear solutions, as used for the preparation of Silicalite-1 zeolite, were synthesized from tetrapropylammonium hydroxide, tetraethylorthosilicate, and water. The solutions analyzed using three techniques: quantitative 29Si NMR, synchrotron small-angle X-ray scattering (SAXS), dynamic light (DLS). NMR showed coexistence silicate oligomers particles. For first time, both fractions simultaneously, providing a global, description solution microstructure. SAXS patterns, typical...

We employ a dynamic micro light scattering technique to probe the thermal concentration fluctuations in surface-attached poly-N-isopropylacrylamide (PNIPAAm) gel layers swollen ethanol as good solvent. At equilibrium swelling state, relaxation function exhibits two decays time range between microseconds and seconds characteristic rates display pure diffusive behavior. The fast cooperative diffusion increases with crosslinking density result of decrease network mesh size. This increase is...

Crowded solutions of densely branched polymers with starlike architecture undergo a reversible gelation upon heating. This phenomenon is characterized by slow kinetics and attributed to the formation clusters causing partial dynamic arrest swollen interpenetrating spheres at high temperatures. A kinetic pseudo-phase diagram temperature against effective volume fraction constructed. Stars different functionalities exhibit sol−gel boundary; small differences in internal structure stars...

Clear solutions for colloidal Silicalite-1 synthesis were prepared by reacting tetraethylorthosilicate in aqueous tetrapropylammonium hydroxide solution. A dilution series with water resulting clear a TEOS ∶ TPAOH H2O molar ratio of 25 9 152 up to 15 000 was analysed using liquid 29Si nuclear magnetic resonance (NMR), synchrotron small angle X-ray scattering (SAXS) and dynamic light (DLS). Particle sizes derived independently from DLS the combination SAXS NMR. NMR allowed quantitative...

We present the theory and experimental details for chiral-cavity-ring-down polarimetry magnetometry, based on ring cavities supporting counterpropagating laser beams. The optical-rotation symmetry is broken by presence of both chiral Faraday birefringence, giving rise to signal reversals which allow rapid background subtractions. measurement specific rotation at 800 nm vapors α-pinene, 2-butanol, α-phellandrene, optical sucrose solutions in a flow cell, Verdet constant fused silica,...

We investigate the conformation of well-defined dendronized polymers (denpols) based on poly(norborene) (PNB) and poly(endo-tricycle[4.2.2.0]deca-3,9-diene) (PTD) backbones employing static dynamic light scattering. Their synthesis by ring-opening metathesis polymerization (ROMP) led to fully grafted high molecular weight denpols with narrow polydispersity. In dilute solutions, persistence lengths were estimated (radius gyration) (translational diffusion) chain conformational properties...

Well-defined dendronized polymers (denpols) bearing high-generation dendron are attractive nano-objects as high persistency provides distinct properties, contrast to the random coiled linear However, their syntheses via graft-through approach have been very challenging due structural complexity and steric hindrance retarding polymerization. Here, we report first example of synthesis poly(norbornene) (PNB) containing ester dendrons up sixth generation (G6) by ring-opening metathesis This is...

We elucidate the effect of preparation conditions on rheological properties organophilic clays consisting platelet-like primary particles, VG69 (trademark SLB) dispersed in oil, by varying homogenization rate, temperature, and amount added water. establish that stable, nonsedimenting gel formation requires temperatures higher than 45 °C addition a small water during stage. Dried organoclay dispersions, other hand, do not form stable gels, independent rate suggesting existence only weak...

We investigated the effects of high hydrostatic pressure on sol-gel transition gelatin dispersions. used dynamic light scattering (DLS) and DLS-based passive microrheology to monitor evolution viscoelasticity during isothermal gelation. It provided easy identification critical gelation time (t c) values viscosities sols shear modulus gels. At a given temperature, t c decreased with increasing pressure. Up 100 MPa, temperature dependence followed established empirical rule T increased by...

Polymacromonomers are viewed as a special class of well-characterized branched polymers with high density arms and shape ranging from spherical to nonspherical, depending on the arm functionality molecular mass. We synthesized series such model systems polystyrene or poly(methyl methacrylate) backbone varying and/or mass investigated their structure dynamics in nondilute solutions (well above overlapping concentration c*) melt. found similarities soft ordering dynamic response other...

The dynamic structure of a chemically end-grafted polystyrene brush bathed in solvents varying interactions was studied by evanescent wave light scattering. It reveals distinct behavior under good and poor solvent conditions. cooperative diffusion is generic feature environment, whereas second slow relaxation mode appears the theta regime. Its characteristics resemble self-diffusion clusters gel while weak concentration fluctuations polymer decay similarly to semidilute solution.

Crowded solutions of multiarm star polymers, representing model colloidal spheres with ultrasoft repulsive interactions, undergo a reversible gelation transition upon heating in solvents intermediate quality (between good and Theta). This unusual phenomenon is due to the kinetic arrest swollen interpenetrating at high temperatures, forming clusters, analogy glass transition. In this work we demonstrate that choice solvent has dramatic effect on transition, because different degree swelling...

In an effort to control particle diffusion near surfaces, we have studied the dynamics of colloidal hard spheres and soft compliant star copolymers on surfaces coated with polymer brushes using evanescent wave dynamic light scattering. The same experiments provide information brush structure confined motion. penetration into dense polydisperse is size- solvent-dependent.

Clay minerals are abundant natural materials used widely in coatings, construction materials, ceramics, as well being a component of drilling fluids. Here, we present the effect steady and oscillatory preshear on organophilic modified clay gels synthetic oil. Both platelet needlelike particles viscosifiers fluid formulations. For both particles, plateau modulus exhibits similar concentration dependence, GP∼c3.9, whereas yield strain is γy∼c−1 for platelets γy∼c−1.7 needles. Mixtures two...

The phase state of polysulfone/polyimide (PSF/PI) blends has been studied by differential scanning calorimetry, rheology, and X-ray scattering. rich in PSF form miscible when prepared solution casting from a common solvent. In these PSF-rich blends, the single dynamic process rheology shifts broadens, with composition reflecting change local friction enhancement concentration fluctuations, respectively. Heating to temperatures above glass transition temperature results separation into PSF-...

Synchrotron small angle X-ray scattering (SAXS) was used to characterize silicalite-1 zeolite crystallization from TEOS/TPAOH/water clear sol. SAXS patterns were recorded over a broad range of length scales, enabling the simultaneous monitoring nanoparticles and crystals occurring at various stages synthesis. A simple two-population model accurately described patterns. Nanoparticles modeled by polydisperse core-shell spheres monodisperse oblate ellipsoids. These models consistent with TEM...

In concentrated clear sol prepared from tetraethylorthosilicate, tetrapropylammonium hydroxide, and water suitable for crystallization of Silicalite-1 zeolite, the main part silica is present in nanoparticles. The nature these nanoparticles their evolution during induction period stage early crystal growth was investigated via dissolution experiments presence excess TPAOH. process monitored situ using static dynamic light scattering (SLS/DLS) synchrotron small-angle X-ray (SAXS). complete an...

Semifluorinated alkyl-azobenzene derivatives (SFAB) can form stable Langmuir layers at the air-water interface. These systems combine amphiphobic character of semifluorinated alkyl units as structure-directing motifs with photochromic behavior based on well-known reversible cis-trans isomerization upon irradiation UV and visible light. Herein, we report our investigations structural dynamic tunability these SFAB interface in response to an external light stimulus. The monolayer structures...

We form films of carboxylated polystyrene particles (C-PS) at the air–water interface and investigate effect subphase pH on their structure rheology by using a suite complementary experimental techniques. Our results suggest that electrostatic interactions drive stability structural order films. In particular, we show increasing from 9 up to 13, exhibit gradual transition solid liquidlike, which is accompanied loss long-range (that characterizes them lower values pH). Direct optical...