Polymer and Organic Materials Commons^™

Nano- And Micro-Structured Temperature-Sensitive Hydrogels For Rapidly Responsive Devices, Qi Lu

Doctoral Dissertations

This thesis aims to extend the understanding and explore the application of temperature-responsive hydrogel systems by integrating microelectromechanical systems (MEMS). Stimuli-responsive hydrogel systems are immensely investigated and applied in numerous fields, and interfacing with micro- and nano-fabrication techniques will open up more possibilities. In Chapter 2, the first biologically relevant, in vitro cell stretching device based on hydrogel surface instability was developed. This dynamic platform is constructed by embedding micro-heater devices under temperature-responsive surface-attached hydrogels. The fast and regional temperature change actuates the stretching and relaxation of the seeded human artery smooth muscle cell (HASMC) via controllable surface creasing instability. …

Nature-Inspired Electrode Materials For Next Generation Sustainable Energy Storage, Mikhail Miroshnikov

Dissertations, Theses, and Capstone Projects

Despite revolutionizing the world of portable electronics, the contemporary lithium-ion battery (LIB) suffers from challenges associated with the cost, safety, and environmental impact of transition metal oxide-based intercalation cathodes. To alleviate these issues, naturally occurring organic molecules may serve as sustainable alternatives to traditional inorganic cathode materials. The electrochemical properties of organic compounds are derived from redox-active functional groups containing oxygen, nitrogen and sulfur. Additionally, these functional groups are capable of coordinating metal ions beyond lithium, allowing for compatibility with sodium-ion batteries (SIBs) and other earth abundant metal-based energy storage systems. However, despite competitive performance against commercialized cathode materials, much …

Bulk Properties Correlated To The Hydrogen Bond Organization In Dendrimers, Hyperbranched Polymers, And Linear Polymers, Beibei Chen

Dissertations

Although a lot of research was conducted on dendritic polymers, our understanding of their structure-property is still limited. Our previous study, which focused on a family of dendritic polymers based on 2,2-bis(hydroxymethyl) propionic acid (bis-MPA) as a monomer, discovered unique hydrogen bond organizations contributed by their dendritic structures. However, the influence of the H-bond organization on bulk properties has yet to be understood. The goal of this dissertation is to elucidate the correlation between the H-bond organization with the dielectric and volumetric properties of bis-MPA based dendritic polymers, with an emphasis on developing a fundamental understanding of to what extent …

Surface Driven Flows : Liquid Bridges, Drops And Marangoni Propulsion, Samrat Sur

Doctoral Dissertations

Molecules sitting at a free liquid surface against vacuum or gas have weaker binding than molecules in the bulk. The missing (negative) binding energy can therefore be viewed as a positive energy added to the surface itself. Since a larger area of the surface contains larger surface energy, external forces must perform positive work against internal surface forces to increase the total area of the surface. Mathematically, the internal surface forces are represented by surface tension, defined as the normal force per unit of length. One common manifestation of surface tension is the difference in pressure it causes across a …

Gravity-Drawing Flexible Silicone Filaments As Fiber Optics And Model Foldamers, Katherine Snell

CMC Senior Theses

Here, we present a method of gravity-drawing polydimethylsiloxane (PDMS) silicone fibers with application as fiber optics and as model foldamers. Beginning as a viscous liquid, PDMS is cured using heat until its measured viscosity reaches 4000 mPa•s. The semi-cured elastomer is then extruded through a tube furnace to produce thin (diameters on the order of hundred micrometers) filaments with scalable lengths. PDMS is biocompatible, gas-permeable, flexible, and hydrophobic. Additionally, the PDMS surface hydrophobicity can be modified via UV exposure, O2 plasma, and corona discharge. We demonstrate the patternibility (i.e patterns of hydrophobicity) of PDMS fibers, adding complexity to potential foldamer …

A Foundational Approach To Extrusion And Compounding, David Frankart

Williams Honors College, Honors Research Projects

With a history of nearly 200 years, polymer processing and compounding is constantly changing to fit the material science needs of the era. Exposure of undergraduate students to the technology and practices used in industry today in a lab setting would create new opportunities for experiential learning and growth. The objective was to set up a 0.75”, 25 L/D Thermo Haake single screw extruder for lab use and run trials of material in a single screw extruder to set up a basis for experiments. Trials were run of co-polyester resin through a single screw extruder with carbon fiber additives varying …

Fabrication, Characterization And Applications Of Highly Conductive Wet-Spun Pedot:Pss Fibers, Ruben Sarabia Riquelme

Theses and Dissertations--Chemical and Materials Engineering

Smart electronic textiles cross conventional uses to include functionalities such as light emission, health monitoring, climate control, sensing, storage and conversion of energy, etc. New fibers and yarns that are electrically conductive and mechanically robust are needed as fundamental building blocks for these next generation textiles.

Conjugated polymers are promising candidates in the field of electronic textiles because they are made of earth-abundant, inexpensive elements, have good mechanical properties and flexibility, and can be processed using low-cost large-scale solution processing methods. Currently, the main method to fabricate electrically conductive fibers or yarns from conjugated polymers is the deposition of the …