Polymer Science Commons^™

Helical Ordering In Chiral Block Copolymers, Wei Zhao

Open Access Dissertations

The phase behavior of chiral block copolymers (BCPs*), namely, BCPs with at least one of the constituent block is formed by chiral monomers, is studied both experimentally and theoretically. Specifically, the formation of a unique morphology with helical sense, the H* phase, where the chiral block forms nanohelices hexagonally embedded in the matrix of achiral block, is investigated. Such unique morphology was first observed in the cast film of polystyrene-b-poly(L-lactide) (PS-b-PLLA) from a neutral solvent dichloromethane at room temperature with all the nanohelices being left-handed, which would switch to right-handed if the PLLA block changes ...

Characterization Of Self-Assembled Functional Polymeric Nanostructures: I. Magnetic Nanostructures From Metallopolymers Ii. Zwitterionic Polymer Vesicles In Ionic Liquid, Raghavendra Raj Maddikeri

Open Access Dissertations

Two diverse projects illustrate the application of various materials characterization techniques to investigate the structure and properties of nanostructured functional materials formed in both bulk as well as in solutions. In the first project, ordered magnetic nanostructures were formed within polymer matrix by novel metallopolymers. The novel metal-functionalized block copolymers (BCPs) enabled the confinement of cobalt metal ions within nanostructured BCP domains, which upon simple heat treatment resulted in room temperature ferromagnetic (RTFM) materials. On the contrary, cobalt functionalized homopolymer having similar chemical structure and higher loading of metal-ion are unstructured and exhibited superparamagnetic (SPM) behavior at room temperature. Based ...

Synthesis Of Narrowly Distributed Low Molecular Weight Polyethylene And Polyethylene Mimics With Controlled Structures And Functionalities, Lai Chi So

Open Access Dissertations and Theses

The controlled synthesis of functional low molecular weight polyethylene and polyethylene mimics is important in tuning polymer properties and is of great industrial interests. Living polymerization is a method that allows for precise control in polymer structure. Although high molecular weight polymers with controlled structures can be efficiently produced via living polymerization, the production of low molecular weight polymers faces the challenges of the use of large amounts of expensive catalyst and the broadening of polydispersity.

The synthesis of well-defined functional low molecular weight polyethylene and polyethylene mimics is studied. Promising polymerization systems, including living ring opening metathesis polymerization (ROMP ...

Wax-Based Emulsifiers For Wax Emulsions For Use In Engineered Wood Products, Nels Grauman Neander

Open Access Dissertations and Theses

In this study new value-added products were developed from four commercially available refined waxes for use as commercial emulsifiers via the technique of maleation. This research was performed in collaboration with an industrial partner with the hope of developing a wax emulsifier product that could replace commercially used wax emulsifiers in engineered wood product emulsions at a cost reduction by beginning with the design of a cost effective process that could be incorporated into an existing factory production line. Through the investigation and subsequent optimization of this process, a highly maleated product was achieved using 6 different quick and simple ...

Interactions And Morphology Of Triblock Copolymer - Ionic Liquid Mixtures And Applications For Gel Polymer Electrolytes, Daniel F. Miranda

Open Access Dissertations

Room temperature ionic liquids (ILs) are a unique class of solvents which are characterized by non-volatility, non-flammability, electrochemical stability and high ionic conductivity. These properties are highly desirable for ion-conducting electrolytes, and much work has focused on realizing their application in practical devices. In addition, hydrophilic and ionophilic polymers are generally miscible with ILs. The miscibility of ILs with ion-coordinating polymers makes ILs effective plasticizers for gel polymer electrolytes. Due to their unique properties, ILs present a means to realize the next generation of energy storage technology. In this dissertation, the fundamental interactions between poly(ethylene oxide) (PEO) and a ...

Chemistry At Silicone - Inorganic Oxide Interfaces, Joseph W. Krumpfer

Open Access Dissertations

This dissertation describes research performed using siloxane polymers. This includes the reactions of siloxane polymers with inorganic oxide surfaces to form covalently attached monolayers, and the electrical properties of crosslinked silicone composite films fabricated by compounding with nickel particles. In addition to these topics, the use of contact line pinning as a practical and controllable method for the deposition of materials on superhydrophobic and chemically patterned surfaces is also described The first chapter provides a general review of siloxane polymer chemistry, focusing in particular on the relationship between molecular structure and physical properties. The use and fabrication of silicone composite ...

Macroscopic Patterning Via Dynamic Self-Assembly And Wrinkling Instability, Hyun Suk Kim

Open Access Dissertations

My PhD work focuses on developing new methods to create the macroscopic patterns in a simple, robust, and versatile way. For macroscopic pattern formation, we first use flow coating as an assembly technique, uniquely balancing two driving forces: (i) evaporative deposition of nonvolatile solutes at a three-phase contact line and (ii) precision movement of a confined meniscus layer. This balance leads to the formation of line-based patterns that range in height and width from nanometers to microns, with lengths greater than centimeters. Moreover, we couple this deposition methodology with functional ligand chemistry on the nanoparticle surface, which allows us to ...

Modulation Of Bone And Nerve Cell Behavior Using Biodegradable Polymer Networks, Lei Cai

Doctoral Dissertations

This dissertation presents novel biodegradable and photo-crosslinkable building blocks to achieve polymer networks with controlled surface chemistry, stiffness, and topographical features for investigating cell-material interactions and targeting hard and soft tissue engineering applications. Chapter I reviews the recent progress in polymeric gel systems and how their physical properties can be tailored to regulate cell functions and satisfy the clinical needs. Chapter II presents a facile method to synthesize photo-crosslinkable poly(epsilon-caprolactone) acrylates (PCLAs) and reveal tunable cell responses to photo-crosslinked PCLAs. Chapter III investigates the mechanism of colorization in preparing crosslinkable polymers by reacting hydroxyl-containing polymers with unsaturated anhydrides or ...

Light And Heat Selective Polymer Nanocomposite Films For Sustainable Greenhouses, Jenna M. Allan

Electronic Thesis and Dissertation Repository

Ontario greenhouse operations offer the ability to provide safe, local produce year-round. However, energy consumption associated with this service, as well as limited light intensity during winter months, is a significant problem. For this reason quantum dot (QD) nanoparticles and silica aerogel (SA) granules were investigated as potential filler materials for the enhancement of the optical and thermal properties of poly (ethylene-vinyl acetate) (EVA), a common greenhouse plastic, for the concurrent goals of increasing biomass production and reducing energy consumption in greenhouses.

The QDs, synthesized by colloidal chemistry using a single-molecular precursor method, along with commercial SA particles were integrated ...

Wax-Based Emulsifiers For Use In Emulsions To Impart Water Repellency To Gypsum Wallboards, Mark T. Rattle

Open Access Dissertations and Theses

Maleation is a common means of modification for many commodity polymers and is used to several ends. In this study, various waxes were functionalized with maleic anhydride through several maleation processes, with the end goal of obtaining a cost effective processes to make emulsifiers to be used in emulsions that impart water-resistance to building products, such as gypsum wallboards. Research was done in collaboration with an industrial partner, in order to replace commercially available emulsifiers currently being used in their processes with a less costly product that could easily be made on-site based on their consumption requirements, through a solvent-free ...

Fabrication Of Paper Based Thermo-Responsive Membranes And Investigation For Their Use In Adsorption Of Emerging Water Contaminants, Evan G. Mah

Open Access Dissertations and Theses

Endocrine disrupting substances have been frequently reported to exist in potent concentrations in wastewater treatment plant effluent and other surface waters. Common techniques of wastewater treatment have varied effectiveness to remove estrogens from wastewater. A thermo-responsive smart membrane technology is investigated for its use in adsorptive removal of 17β-estradiol from a background electrolyte solution. A simplified fabrication method is adapted for hydrogel-substrate composite thermo-responsive membranes. Deposition of hydrogel occurs through aqueous polymerization in a coating process dissimilar to common grafting techniques. Acrylamide and acrylic acid monomers are polymerized in two different structures, a random copolymer as well as an interpenetrating ...

Temporarily Reactive Polyelectrolytes To Improve Long Term Cell Encapsulation, Casandra M. Gardner

Open Access Dissertations and Theses

Coated calcium-alginate beads are the basis of many encapsulation methods used in pursuit of cell-based enzyme and hormone replacement therapies. The standard alginate - poly-L-lysine - alginate (APA) capsules consist of a calcium-alginate hydrogel core containing cells designed to express a therapeutic product, coated with permeability controlling poly-L-lysine (PLL, a polycation) followed by an exterior layer of polyanionic alginate. Although this approach is promising, the required long-term survival of the implanted cells has remained largely elusive as the current APA capsules suffer from several biocompatibility and mechanical strength issues, one of which is the weakening of ionic crosslinks over time, exposing the ...

Large Eddy Simulation (Les) Of Glass Fibre Dispersion In An Internally Spout-Fluidised Bed For Thermoplastic Composite Processing, Xiaogang Yang, Xiaobing Huang, Yuan Zong, Grance Dai

Aeronautical Engineering

Large eddy simulation (LES) has been conducted to investigate glass fibre dispersion in an internally spout-fluidised bed with draft tube and disk-baffle, which was used in the manufacture of long glass fibre reinforced thermoplastic composites. The LES results have demonstrated that the internally spout-fluidised bed with draft tube and disk-baffle can remarkably improve its hydrody-namic behaviour, which can effectively disperse fibre bundles and promote pre-impregnation with resin powder in manufacturing fibre reinforced thermoplastics. The hydrodynamics of the spout-fluidised bed has been investigated and reported in a previous paper (Hosseini et al., 2009). This study attempts to reveal important features of ...