We investigate a variety of different polymer solutions in shear and elongational flow. The shear flow is created in the cone-plate-geometry of a commercial rheometer. We use capillary thinning of a filament that is formed by a polymer solution in the Capillary Breakup Extensional Rheometer (CaBER) as an elongational flow. We compare the relaxation time and the elongational viscosity measured i...

We dlscujs polymer adsorption in a poor solvent. For a single chain we find a wetting transition on an attractive wall when the thermal correlation length f is of the order of the adsorption length D If D is larger than f, for weak adsorption, the polymer chain partially wets the solid surface in the same way as a small liquid drop if D is smaller than f, strong adsorption, the chain forms a fl...

nowdays, production of high quality engine oils is one of the worries of our country’s engine oil industry. in this study, the behavior of four commercial polymers used in nation motor oil industry in obtaining the best viscosity index improver was investigated. in this regard, viscometric behavior, shear stability and polymers’ performance for engine cranking were compared at low temperature. ...

We present a facile microfluidic method for forming narrow chemical gradients in polymer brushes. Co-flow of an alkylating agent solution and a neat solvent in a microfluidic channel forms a diffusion-driven concentration gradient, and thus a gradient in reaction rate at the interface of the two flows, leading to a quaternization gradient in the underlying poly(2-(dimethylamino)ethyl methacryla...

A solution blow spinning technique was developed using elements of both electrospinning and melt blowing technologies as an alternative method for making non-woven webs of microand nanofibers with diameters comparable with those made by the electrospinning process with the advantage of having a fiber production rate (measured by the polymer injection rate) several times higher. The diameters of...

One of the challenges in polymer science has been to prepare large-polymer single crystals. We demonstrate a visible light-triggered quantitative topochemical polymerization reaction based on a conjugated dye molecule. Macroscopic-size, high-quality polymer single crystals are obtained. Polymerization is not limited to single crystals, but can also be achieved in highly concentrated solution or...

A disorder-dependent Gaussian variational approach is applied to the problem of a d dimensional polymer chain in a random medium (or potential). Two classes of variational solutions are obtained. For d < 2, these two classes may be interpreted as domain and domain wall. The critical exponent ν describing the polymer width is ν = 1 (4−d) (domain solution) or ν = 3 (d+4) (domain wall solution). T...

Morphology of conjugated polymers is a critical factor that significantly affects intrinsic charge transport characteristics and in turn performance of polymer-based devices. Morphological defects including misaligned crystalline grains and grain boundaries significantly impede efficient charge hopping between transport sites, resulting in degradation of device performance. Therefore, one impor...

The spin coating of thin (> 200 nm thick) and ultrathin (< 200 nm thick) polymer films is examined in several solvents of varying volatility over a broad range of polymer solution concentrations and spin speeds. Experimentally measured film thicknesses are compared with a simple model proposed by Bornside, Macosko, and Scriven, which predicts film thickness based on the initial properties of th...

We analyze a system consisting of two spherical particles immersed in a polydispersed polymer solution under theta conditions. An exact theory is developed to describe the potential of mean force between the spheres for the case where the polymer molecular weight dispersity is described by the Schulz-Flory distribution. Exact results can be derived for the protein regime, where the sphere radiu...