The Morgan Research Group primary research interest is in the area of polymer surfaces and interfaces, with specific focus on surface modification and elucidating mechanisms at the molecular level determining material performance. Research materials include both high performance materials, including composites, nanocomposites, nanostructured materials, polymer coatings and films, and biological and bioinspired polymer films, including self-assembling systems. Current research in high performance materials is focused on adhesion, nanomechanical performance, rheology and dispersion in composite/nanocomposite matrices.
Biopolymer and bio-inspired research focuses on self-assembling systems for sensor applications and surface modification for antifouling/antimicrobial properties. Surface analysis capability includes atomic force microscopy, ATR-FTIR, nanoindentation, SEM-EDAX, surface Plasmon resonance, quartz crystal microbalance, tribometry, ellipsometry, contact angle goniometry and comprehensive coatings analysis capability.
Current High Performance Materials ProjectsSurface and Interfacial Design and Control of High Performing Thermoplastics: Polysulfones and Beyond
A systematic understanding of physical properties in the immediate vicinity of surface and interfacial layers, which cannot be deduced by simple extrapolation of bulk properties, is of critical importance for advancements in polymer applications where the interface drives performance, such as in membranes, coatings, thermoplastic elastomers, and composites. It is the purpose of this research to gain a fundamental understanding of the environmental and structural parameters that determine polymer chain conformation, organization, phase separation, and dynamics at various interfaces for a series of high performing thermoplastics. This core concept has branched into three major research themes: surface and interfacial behavior of semi-rigid/rigid rod sulfone polymers, phase separation in elastomeric polyisobutylene based miktoarm star terpolymers, and nanophase control of polyhedral oligomeric silsesquioxane (POSS) filled semi-crystalline poly(phenylene sulfide) and poly(ether ether ketone) nanocomposites.
Synthesis of conjugated small molecules and polymers for applications in organic photovoltaics present the potential to be cost-effective and readily produced. The focus of these materials is on increased environmental stability and light absorption in order to improve the longevity and efficiency of presently used organic photovoltaic materials. In particular, derivatives of perylene bisimides, industrially important dyes known for their environmental robustness, are utilized as the replacement for fullerenes, the present technological standard, as the electron transport material in polymer photovoltaics. These perylene derivatives improve on the properties of the fullerenes through tunable solubility and processability, increased light absorption, and enhanced environmental stability.
Co-extrusion is widely applied in plastic industry. However, the viscoelasticity difference between multiphase melts and no-slip adhesive shearing extrusion mechanism prone to cause die swell, viscous encapsulation and interfacial instability. To solve these problems, we proposed the innovative gas-assisted co-extrusion (GACE) by combining the co-extrusion and gas-assisted technique. In GACE, two or more polymer melts are co-extruded without shear in a plug flow type with a gas layer flowing between die wall and polymer melts. In previous study, we established the GACE experimental system and 3D viscoelastic non-isothermal FEM model. Through experiments and simulations we found GACE can practically eliminate die swell, remarkably decrease the degree of encapsulation and improve the stability of interface. Also, we revealed the fundamental mechanism of GACE by analyzing the physical field variables of polymer melts. The more in-depth study is being implemented focusing on the interaction between gas layer and polymer melts and the application technique of GACE.
Current Bioinspired Materials ProjectsSynthesis of Glycopolymer Hydrogels for the Determination of the Effects of Network Architecture on Water Structure and Hydration Processes
Hydrogels are polymeric networks that absorb a significant amount of water but are insoluble due to the crosslinked nature. Network architecture and composition is known to significantly impact the overall water content and state of water within a hydrogel network which subsequently influences network properties such as optical transparency, mechanical stability, and oxygen permeability. Water within a hydrogel network exists in three discrete states (bound, restricted, and free), which is characterized by the degree of hydrogen bonding between a water molecule and the hydrogel network. Glycopolymer analogues of naturally occurring polysaccharides provide a viable synthetic route to capitalize on the hydration properties inherent of natural polysaccharides while providing greater freedom in tailoring network design and architecture through the potential of copolymer networks. In recent studies we have synthesized stereospecific-acrylamide based glycomonomers containing pendant glucose and galactose moieties via UV initiated free radical polymerization. Overall water content and structural water distribution of analogous networks comprised of glucose and galactose were analyzed utilizing TGA and DSC.
One of the fundamental causes of Alzheimer’s disease (AD) is the aggregation and deposition of amyloid beta (Aβ) peptide on neuronal membranes. The factors responsible for Aβ aggregation and the mechanism of aggregation are not yet fully understood. Ganglioside GM1 is believed to act as a modulator which promotes the aggregation of Aβ. Stereospecific glycopolymers with either glucose or galactose as pendant groups were synthesized in solution and on surfaces to mimic the saccharides of GM1. These glycopolymers will be utilized as models to mimic Aβ/GM1 saccharide interactions in the neuronal membranes.
Celiac disease (CeD) is an autoimmune disorder that arises after the ingestion of gliadin (a component of gluten) in genetically predisposed individuals. However, the precise mechanisms and influence of polymer binder systems on the CeD process, specifically in relation to the gliadin triggered processes, are not well understood. Synthesis of low molecular weight anionic acrylamide-based (co)polymers that electrostatically bind to the gliadin surface will elucidate polymer binder mechanisms on the molecular level and at the polymer-protein interface. This research provides platform for investigation of polymer-protein structure/binding relationships and food allergen/proteopathic research, where polymer-binder systems act as therapeutic agents.
Naturally occurring antimicrobial peptides (AMPs) display the ability to eliminate a wide variety of bacteria, without toxicity to the host eukaryotic cells. Synthetic polymers containing moieties mimicking lysine and arginine components found in AMPs have been reported to show effectiveness against specific bacteria, with the mechanism of activity purported to depend on the nature of the amino acid mimic. Our ultimate goal is to investigate the effectiveness of guanidiniums moieties within our established methacrylamide based platform for AMP mimic development and tailoring via tuning of (co)polymer composition. This research aims to increase antimicrobial activity and selectiveness across a broader spectrum of bacteria through pairing of increased solubility of methacrylamide polymer backbone and guanidinium pendant groups.