University of Akron

About: University of Akron is a education organization based out in Akron, Ohio, United States. It is known for research contribution in the topics: Polymer & Polymerization. The organization has 17401 authors who have published 29127 publications receiving 702386 citations. The organization is also known as: The University of Akron.

Synthesis of Polycarbonate-Layered Silicate Nanocomposites via Cyclic Oligomers

Abstract: A partially exfoliated bisphenol A polycarbonate nanocomposite has been prepared by using carbonate cyclic oligomers and ditallow dimethyl exchanged montmorillonite (B34). Wide-angle X-ray diffraction (WAXD) indicated that exfoliation of this organically modified layered silicate (OLS) occurs after mixing with the cyclic oligomers in a brabender mixer for 1 h at 180 °C. Subsequent ring-opening polymerization of the cyclic oligomers converted the matrix into linear polymer without disruption of the layer dispersion. Transmission electron microscopy revealed that a partially exfoliated structure was obtained, although no indication of layer correlation was observed in WAXD. If linear polycarbonate was similarly treated with B34 in a brabender mixer, only an intercalated hybrid was obtained. Furthermore, conventional melt or solution processing of the B34 with either linear polycarbonate or cyclic oligomers yielded intercalated nanocomposites with interlayer spacings of 3.27 and 3.6−3.8 nm, respectively. The...

Attitudinal Congruence and Similarity as Related to Interpersonal Evaluations in Manager-Subordinate Dyads

Abstract: This field study examined the relationship of both actual similarity and perceptual congruence with job satisfaction and performance evaluation in 194 manager-subordinate dyads. Among other finding...

Giant surfactants provide a versatile platform for sub-10-nm nanostructure engineering

Abstract: The engineering of structures across different length scales is central to the design of novel materials with controlled macroscopic properties. Herein, we introduce a unique class of self-assembling materials, which are built upon shape- and volume-persistent molecular nanoparticles and other structural motifs, such as polymers, and can be viewed as a size-amplified version of the corresponding small-molecule counterparts. Among them, “giant surfactants” with precise molecular structures have been synthesized by “clicking” compact and polar molecular nanoparticles to flexible polymer tails of various composition and architecture at specific sites. Capturing the structural features of small-molecule surfactants but possessing much larger sizes, giant surfactants bridge the gap between small-molecule surfactants and block copolymers and demonstrate a duality of both materials in terms of their self-assembly behaviors. The controlled structural variations of these giant surfactants through precision synthesis further reveal that their self-assemblies are remarkably sensitive to primary chemical structures, leading to highly diverse, thermodynamically stable nanostructures with feature sizes around 10 nm or smaller in the bulk, thin-film, and solution states, as dictated by the collective physical interactions and geometric constraints. The results suggest that this class of materials provides a versatile platform for engineering nanostructures with sub-10-nm feature sizes. These findings are not only scientifically intriguing in understanding the chemical and physical principles of the self-assembly, but also technologically relevant, such as in nanopatterning technology and microelectronics.

The Effect of Non-linear Piezoelectric Coupling on Vibration-based Energy Harvesting

Abstract: Advances in electronic and consumer technology are increasing the need for smaller, more efficient energy sources Thus vibration-based energy harvesting, the scavenging of energy from existing ambient vibration sources and its conversion to useful electrical power, is becoming an increasingly attractive alternative to traditional power sources such as batteries Energy harvesting devices have been developed based on a number of electromechanical coupling mechanisms and their design must be optimized to produce the maximum output for given environmental conditions While the role of non-linearities in the components has been shown to be significant in terms of the overall device efficiency, few studies have systematically investigated their influence on the system performance In this work the role of a non-linear piezoelectric relationship is considered on the performance of a vibration-based energy harvester Using a Poincare-Lindstedt perturbation analysis the response of the harvesting system is appro