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Block copolymers remain one of the most extensively investigated classes of polymers due to their abilities to self-organize into various nanostructures and modify polymer/polymer interfaces. Despite fundamental and technological interest in these materials, only a handful of experimental phase diagrams exist due to the laborious task of preparing such diagrams. In this work, two copolymer series...
This feature article summarizes recent advances in an emerging three-dimensional (3D) imaging technique, transmission electron microtomography (TEMT), and its applications to polymer-related materials, such as nanocomposites and block copolymer morphologies. With the recent developments made in TEMT, it is now possible to obtain truly quantitative 3D data with sub-nanometer resolution. A great deal...
Linear polyethers possess unusually high CO 2 solubility and, hence, selectivity due to the presence of accessible ether linkages that can interact with the quadrupolar moment of CO 2 molecules. In this work, membranes derived from crosslinked poly(propylene glycol) diacrylate (PPGda) oligomers differing in molecular weight (M), as well as PPGda nanocomposites containing either an...
Use of supercritical carbon dioxide (scCO 2 ) as a blowing agent to generate microcellular polymer foams (MPFs) has recently received considerable attention due to environmental concerns associated with conventional organic blowing agents. While such foams derived from amorphous thermoplastics have been previously realized, semicrystalline MPFs have not yet been produced in a continuous scCO...
Conductive polymer composites are ubiquitous in technological applications and constitute an ongoing topic of tremendous commercial interest. Strategies developed to improve the level of electrical conductivity achieved at a given filler concentration have relied on double-percolated networks induced by immiscible polymer blends, as well as mixtures of fillers in a single polymer matrix, to enhance...
The development of conductive polymer composites remains an important endeavor in light of growing energy concerns. In the present work, graphite (G), carbon fiber (CF) and G/CF mixtures are added to high-density polyethylene (HDPE) to discern if mixed fillers afford appreciable advantages over single fillers. The effects of filler type and composition on electrical conductivity, composite morphology...
Hydrogels constitute an important class of responsive materials that are employed in numerous biomedical and personal-care applications, most notably of which are controlled drug delivery, separations and superabsorbency. Since aqueous hydroxypropylcellulose (HPC) solutions exhibit lower critical solution behavior, hydrogels produced from this cellulose ether are temperature-responsive, swelling at...
Topological coarsening of block copolymer ultrathin films is well-understood for copolymers exhibiting intermediate or strong segregation and differing in film thickness or molecular weight at temperatures above the upper glass transition temperature (T g ), but below the order-disorder transition (T ODT ), of the copolymers. More recent studies suggest that the stability...
Studies examining the structure of monolayers formed by polymer chains grafted to a surface typically focus on chains attached at one end (tails). Bond fluctuation simulations are performed here to probe monolayers composed of equimolar mixtures of tails and double-grafted loops in which the looped chain length (Nloop) is varied at constant surface density and tail length (Ntail). Loops force the...
Property modification of an inorganic surface can be readily achieved through the use of macromolecules chemically grafted to the surface at specific functional sites along the chain. While numerous efforts have addressed the properties of linear chains grafted at one end (tails), relatively few have extended such studies to include double-tethered chains (loops). In this work, we consider loop/tail...
Chemical incorporation of a flexible molecule into a heat-cured epoxy offers an important route by which to toughen the epoxy and tailor its ultimate material properties. Acrylate-terminated urethane (ATU) flexibilizers containing polypropylene glycol have been employed in the present work to modify epoxies composed of a diglycidyl ether of bisphenol-A and bis(4-aminocyclohexyl) methane. Differential...
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