Related papers: Short Chains Enhance Slip of Highly Entangled Poly…
Slippage of Newtonian liquids in the presence of a solid substrate is a newly found phenomenon the origin of which is still under debate. In this paper, we present a new analysis method to extract the slip length. Enhancing the slip of…
Hydrodynamic slip of Newtonian liquids is a new phenomenon, the origin of which is not yet clarified. There are various direct and indirect techniques to measure slippage. Here we describe a method to characterize the influence of slippage…
While nearly all theoretical and computational studies of entangled polymer melts have focused on uniform samples, polymer synthesis routes always result in some dispersity, albeit narrow, of distribution of molecular weights (D_M=M_w/M_n ~…
The dewetting dynamics of ultrathin polymer films, e.g. in the model system of polystyrene on a polydimethylsiloxane-covered substrate, exhibits interesting behavior like a fast decay of the dewetting velocity and a maximum in the width of…
Dewetting of ultrathin (< 100 nm) polymer films, by heating above the glass transition, produces droplets of sizes of the order of microns and mean separations between droplets of the order of tens of microns. These relatively large length…
Synthetic polymers have a distribution of chain lengths which can be characterized by dispersity, D. Macroscopic properties of polymers are influenced by chain mobility in the melt and manipulating D can significantly impact these…
Dewetting of thin polystyrene films deposited onto silicone wafers at temperatures close to the glass transition exhibits unusual dynamics and front morphologies. Here, we present a new theoretical approach of these phenomena taking into…
The slip phenomena in thin polymer films confined by either flat or periodically corrugated surfaces are investigated by molecular dynamics and continuum simulations. For atomically flat surfaces and weak wall-fluid interactions, the shear…
The shear rate dependence of the slip length in thin polymer films confined between atomically flat surfaces is investigated by molecular dynamics simulations. The polymer melt is described by the bead-spring model of linear flexible…
We present an experimental method allowing to quantify slip at the wall in viscous polymer fluids, based on the observation of the evolution under simple shear flow of a photobleached pattern within a fluorescent labeled polymer melt. This…
In this study, we present a novel method to assess the slip length and the viscosity of thin films of highly viscous Newtonian liquids. We quantitatively analyse dewetting fronts of low molecular weight polystyrene melts on Octadecyl- (OTS)…
The study of the dewetting of very thin polymer films has recently revealed many unexpected features (e.g. unusual rim morphologies and front velocities) which have been the focus of several theoretical models. Surprisingly, the most…
The interface between two immiscible polymers, polystyrene (PS) and polydimethylsiloxane (PDMS), was studied by neutron reflectivity and dewetting by using free PS chains and PDMS brushes. Unexpectedly, we found that the PS chains diffuse…
This study focuses on comparing the individual polymer chain dynamics in an entangled polymeric liquid under different shear and extension rates. Polymer chains under various shear rates and extension rates were simulated using a…
Ultrathin polymer films on non-wettable substrates display dynamic features which have been attributed to either viscoelastic or slip effects. Here we show that in the weak and strong slip regime effects of viscoelastic relaxation are…
An experimental investigation is reported on the effect of shear on the bursting of molten ultra-thin polymer films embedded in an immiscible matrix. By using an optical microscope coupled with a shearing hotstage, the dewetting dynamics,…
In some recent experiments on entangled polymers of stress growth in startup of fast shear flows an undershoot in the shear stress is observed following the overshoot, i.e., before approaching the steady state. Whereas tumbling of the…
Random packings of granular chains are presented as a model polymer system to investigate the contribution of entanglements to strain-stiffening in the absence of Brownian motion. The chain packings are sheared in triaxial compression…
We investigate the behavior of the slip length in Newtonian liquids subject to planar shear bounded by substrates with mixed boundary conditions. The upper wall, consisting of a homogenous surface of finite or vanishing slip, moves at a…
Alkylsilane self-assembled monolayers (SAMs) are often used as model substrates for their ease of preparation and hydrophobic properties. We have observed that these atomically smooth monolayers also provide a slip boundary condition for…