Conditions of rapid processing often drive polymers to adopt nonequilibrium molecular conformations, which, in turn, can give rise structural, dynamical, and mechanical properties that are significantly different from those thermodynamic equilibrium. However, despite the possibility control desired polymers, a rigorous microscopic understanding processing–property relations is currently lacking. In an attempt stimulate progress along this topical direction, we focus here on three...

While the interplay between liquid-liquid phase separation (LLPS) and glass formation in biological systems is highly relevant for their structure thus function, exact underlying mechanisms are not well known. The kinetic arrest originates from slowdown at molecular level, but how this propagates to dynamics of microscopic domains clear. Since with diffusion, viscoelasticity, hydrodynamics, distinctly different play, needs be monitored on time length scales compared theories separation....

The kinetics of heat-induced gelation and the microscopic dynamics a hen egg white gel are probed using x-ray photon correlation spectroscopy along with ultrasmall-angle scattering. structural growth reveals reaction-limited aggregation process fractal dimension ≈2 an average network mesh size ca. 400 nm. at these length scales exponential characteristic relaxation times followed by intriguing steady state in combination compressed function temporal heterogeneity. degree heterogeneity...

Polymer materials are commonly processed at rates higher than those which their molecules spontaneously reach equilibrium conditions. The resulting nonequilibrium conformations might significantly affect the mechanical behavior and shelf time of final products. To understand how processing–properties relations work, we investigated impact spin coating, an archetypical method to fabricate thin polymer layers. By using a geometry in frozen over sufficiently long experimental times, could...

Performance and properties of materials may strongly depend on processing conditions. This is particularly so for polymers, which often have relaxation times much longer than the therefore adopt preparation dependent nonequilibrated molecular conformations that potentially cause novel properties. However, far it was not possible to predictably quantitatively relate steps resulting polymer films. Here, we demonstrate behavior films, probed through dewetting, can be tuned by controlling...

We compare the high velocity dewetting behavior, at elevated temperatures, of atactic polystyrene (aPS) and isotactic (iPS) films, with zero shear bulk viscosity (η_{bulk}) aPS being approximately ten times larger than iPS. As expected, for apparent films (η_{f}) derived from high-shear is less η_{bulk}, displaying a thinning behavior. Surprisingly, iPS η_{f} always even about 50 °C above melting point, η_{f}/η_{bulk} following an Arrhenius The corresponding activation energy ∼160±10 kJ/mol...

We probed the relaxation of preparation-induced residual stresses in nonequilibrated polymer films through dewetting experiments. While we observed fast relaxations at temperatures close to or below glass transition, elevated these times were orders magnitude longer than reptation time. Intriguingly, applying appropriate scaling preparation conditions allowed us present all times, including published data, from various complementary experiments on a single master curve exhibiting an...

Processing ultra-high molecular weight polymers presents significant experimental challenges due to their high viscosity, which requires elevated shear rates and consequently increases energy demands. Here, we explored the role of geometry nanoparticles – spheres, rods, tetrapods in controlling effective viscosity polymer nanocomposites. Intriguingly, our combined experiments dynamics simulations reveal a decrease composites with tetrapod nanoparticles, without compromising mechanical or...

The authors propose retransmission error control schemes for broadcast channels. In their selective-repeat-ARQ (automatic repeat request) method, they incorporate some aspects of implementation that believe were ignored by all the previous work. Based on this protocol, also a type-2 hybrid ARQ scheme uses parity retransmission. They apply dynamic programming optimization technique Wang and Silvester (1987), with modification, to schemes. Analysis shows outperform existing As special cases...

We report the variation of glass transition temperature in supported thin films polymer nanocomposites, consisting grafted nanoparticles embedded a homopolymer matrix. observe systematic estimated Tg, with volume fraction added nanoparticles. have correlated observed Tg underlying morphological transitions nanoparticle dispersion films. Our data also suggest possibility formation low-mobility or gel-like layer at interface, which could play significant role determining provided.

Abstract In this paper systematic changes in the isothermal crystallization kinetics (at T c = 200 °C) of nonequilibrated isotactic polystyrene films, generated through spin coating are reported. Kinetics is tuned by annealing films at a 250 °C, i.e., above their nominal melting temperature ( m DSC 220 °C). An exponential decrease growth rate and significant crystal nucleation density approximately three orders magnitude observed increasing time t ) provided for equilibration . The...

We report novel morphologies with periodic height modulations of isotactic polystyrene (iPS) crystals, resulting from alternating stacks correlated lamellae. Systematic experiments were performed on iPS films several thicknesses (h) for varying degrees undercooling, ΔT = Tm∞ – TC, where and TC are the equilibrium melting temperature crystallization temperature, respectively. demonstrate that spatial period (λ), i.e., mean distance between neighboring lamellae, exhibits a power-law dependence...

One of the central dogmas fluid physics is no-slip boundary condition, whose validity has come under scrutiny, especially in fields micro and nanofluidics. Although various studies show violation condition its effect on flow colloidal particles viscous media been rarely explored. Here we report unusually large reduction effective viscosity experienced by polymeric nano colloids moving through a highly confined polymer, well above glass transition temperature. The extent interface increases...

Dense bacterial suspensions display collective motion exhibiting coherent flow structures reminiscent of turbulent flows. However, in contrast to inertial turbulence, the microscopic dynamics underlying turbulence is only beginning be understood. Here, we report experiments revealing correlations between and emergence suspensions. Our results demonstrate existence three dynamical regimes: initial ballistic followed by an intermittent Lévy walk before intriguing decay random Gaussian...

Because of its smallness and low probability formation, the determination size critical primary nucleus represents a great challenge in polymer crystallization. We are still missing feasible approach providing experimental access to nucleation. In this work, we investigated dependence incubation time on degree supersaturation for well-defined metastable regime prototypical conjugated polymer, i.e., poly(3-hexylthiophene). On basis Kashchiev's nucleation theorem verified by simulation model...

Using dewetting as a characterization tool, we demonstrate that physical properties of thin polymer films can be regulated and tuned by employing variable processing conditions. For different molecular weights, the behavior polystyrene identical thickness, prepared along systematically altered pathways, became predictable through single parameter $\mathcal{P}$, defined ratio time required over available for equilibration polymers. In particular, preparation-induced residual stresses,...

Dispersion of nanoparticles in polymer nanocomposite films determines the application potential these systems as novel materials with unique physical properties. Grafting polymers to, mostly inorganic, has been suggested an effective strategy to enhance dispersion and hence efficacy materials. In this review, we discuss various parameters which control grafted films. We how surface x-ray scattering microscopy can provide complementary information thin unravel subtle interplay entropic...

We investigated the formation of crystalline structures conjugated poly(3-hexylthiophene) (P3HT) from supersaturated solutions. To this end, we induced crystallization by changing solubility through diffusion a poor solvent into homogeneous P3HT solution. An adapted seeding process was employed based on an increase in solution temperature combined with decrease amount By adjusting concentration gradient solvent, achieved spatially controlled conditions supersaturation, including regions slow...

Abstract The stability of thin liquid films on a surface depends the excess free energy system involving various short‐range and long‐range interactions. When forced to wet an unfavorable surface, dewet into multiple small‐sized droplets via spinodal, homogeneous, or heterogeneous nucleation process. However, if total can be manipulated using external stimuli, for example, electric field, temperature, light, one control demand. Here electric‐field induced reversible dewetting rewetting...

Selective repeat automatic-repeat-request (ARQ) schemes with finite receiver buffer have been studied and analyzed extensively for point-to-point communications. In this paper, we propose a selective ARQ scheme point-to-multipoint communications where each has size. A lower bound on the throughput efficiency of proposed is obtained. Computation simulation reveal that performs quite satisfactorily, particularly channels large round-trip delay high data rate like satellite channel. The...