Master of Science, University of Akron, 2024, Polymer Science

Adhesives are commonly used in art restoration, and one of the most essential synthetic adhesives was introduced by Gustav Berger's BEVA in 1970 for relining artworks. For improving low-temperature tackiness, this adhesive formulation is dissolved in toluene and applied onto a relining canvas. However, this process relies on the use of solvents that are not good for health and environmental concerns. My research is focused on reducing the use of toluene and developing water-dispersed formulations. The amount of toluene-water mixture was optimized to prepare stable dispersion with the required adhesive content and the optimum activation temperature required for the relining of the canvas. To enhance the duration of suspension stability, surfactants were added, which increased the shelf-life of the dispersion. The goal of my research was to offer a safer and environmentally friendly method for preserving cultural heritage.

Committee: Dr. Ali Dhinojwala (Advisor); Dr. Abraham Joy (Committee Member) Subjects: Materials Science

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2024, Photochemical Sciences

In 2022, silicon materials had a worldwide market value of 19.94 billion dollars, and it is estimated to steadily increase by 6.1% by 20301. Interest in silicon-based materials has expanded over the years due to their ability to impart high thermal stability, chemical inertness, durability, biocompatibility, and hydrophobicity. Their unique chemical and physical properties are attributed to the Si-O bond strength and the vastly tunable functionalities within attached organic groups, which is a reason they are widely used in the fields of medicine, and high-performance technology applications. These materials, however, require large amounts of energy and release large amounts of CO2 to produce, but then are only very minimally recycled or reprocessed. Thus, it is beneficial and cost effective if silicon materials such as silicones/siloxanes were not simply discarded, but able to be recycled/upcycled or reused multiple times with low energy cycling. Previous work by our lab demonstrated a simply way of recycling siloxane polymers/elastomers by degrading them at room temperature with a F- catalyst. The products of the degradation were cyclic siloxanes (D4, D5, D6) that are commercially used as building blocks to make siloxane polymers. Chapter 1 will give a literature background and analysis to set the stage for recycling and developing reprocessable silicones. Chapter 2 will contain the detail the synthetic and characterization methods used related to the studies of the supramolecular siloxane polymers, and degraded silicones discussed within this work. Chapter 3 will entail mechanistic and solvent studies of the F-catalyzed depolymerization of silicones to cyclic siloxanes and how this information can be used to control the outcome of the reactions. Chapter 4 will focus on Zn2+ and Cr3+ linked reversible supramolecular silicones that are responsive to light and heat to give metal-ligand dynamic bonding systems (adhesives/elastomers) as an alternative method to reproc (open full item for complete abstract)

Committee: Joseph Furgal Ph.D. (Committee Chair); Hong Lu Ph.D. (Committee Member); Alexis Ostrowski Ph.D. (Committee Member); Lee Nickoson Ph.D. (Other) Subjects: Chemistry; Materials Science

Master of Science, University of Toledo, 2023, Chemical Engineering

Multilayer plastics (MLPs) have become one of the most common food packaging materials. By combining multiple polymer types with distinct advantageous properties (e.g., water, light, or oxygen barrier properties), they extend the product shelf life while using less material. Yet, MLPs are challenging to recycle because their layers are difficult to separate, and this difficulty now presents a formidable sustainability challenge. To this end, we have developed new tie-layer materials through the complex coacervation (i.e., self-assembly) between the cationic polyelectrolyte, polyallylamine (PAH) and unsaturated, anionic fatty acids (either oleic acid or linoleic acid). Akin to the liquifying effects of double bonds in cis-unsaturated fats, the double bonds in these fatty acid tails imparted the otherwise-flaky PAH/surfactant complex precipitates with either moldable semisolid or liquid (coacervate) properties. These coacervates were prepared in two different solvents (water and ethanol) and were capable of (1) adhering two dissimilar plastic layers, (2) dissociating during recycling, thus enabling facile separation of MLP layers for further processing, and (3) as a bonus, serving as oxygen scavengers. These complexes exhibited tunable rheological properties, which ranged from viscous liquids (when solvated in ethanol) to putty-like semisolids (when formed in water) and coincided with solvent-dependent changes in their microstructure, where replacing water with ethanol led to a disruption of their lamellar order. Moreover, when prepared as low-viscosity dispersions of submicron coacervate droplets suspended in ethanol, these coacervates could be easily spread onto plastic substrates and (on partial drying) formed adhesive films that could bond dissimilar plastic layers, such as polyethylene terephthalate (PET), low-density polyethylene (LDPE), and ethylene vinyl alcohol (EVOH), with fewer defects and higher adhesion strengths than those achieved by spreading macro (open full item for complete abstract)

Committee: Yakov Lapitsky (Committee Chair); Maria Coleman (Committee Member); Joseph Lawrence (Committee Co-Chair) Subjects: Chemical Engineering; Chemistry; Packaging

Master of Science, University of Toledo, 2021, Chemical Engineering

Polyelectrolytes are polymers with ionizable groups on their chains, which (like regular electrolytes) become charged when dissolved in solution. Polyelectrolytes are widely used in areas including drug delivery, water treatment, and underwater adhesives. The polyelectrolyte examined here is polyallylamine (PAH), which can be crosslinked by multivalent counterions, such as sodium tripolyphosphate (TPP), to form adhesive viscoelastic materials known as coacervates. PAH-based adhesives have previously been shown to be able to adhere to both hydrophobic and hydrophilic surfaces under water. The adhesive properties of these coacervates can also be reversed by raising or lowering the pH. This thesis further explores the rheological and adhesion properties of underwater adhesive coacervates formed via the coacervation of PAH and TPP. The adhesive properties of the material are examined on various substrates, including stainless steel, copper, polyvinyl chloride, polyethylene, and polypropylene under varying pH and ionic strength conditions. The adhesion strengths achieved with PAH/TPP coacervates are also examined in various water types, such as tap water, lake water, and artificial seawater. iv Finally, the shelf-life of the adhesive coacervates is studied over a 9-month storage period while varying the solution pH and ionic strength used during their preparation and their storage temperature. The PAH/TPP coacervates, when prepared from neutral-pH parent PAH and TPP solutions, deliver the highest adhesion strength (with tensile bond strengths on stainless steel surfaces reaching 0.6 MPa), which remains undiminished when the deionized water medium is replaced with tap, lake, or artificial seawater. The coacervates can also bond low-energy surfaces, such as high-density polyethylene, consistently delivering tensile adhesion strengths above 0.1 MPa with all examined substrates. Finally, the rheological and adhesion properties of PAH/TPP coacervates c (open full item for complete abstract)

Committee: Yakov Lapitsky Dr. (Committee Chair); Matthew Liberatore Dr. (Committee Member); Maria Coleman Dr. (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy, University of Akron, 2020, Polymer Science

Mechanical and Antimicrobial Properties of Degradable Quaternary Ammonium Compound Thiol-yne Elastomers. Antimicrobial polymers are an important biomedical material for preventing bacterial infections of implanted devices. Antimicrobial activity is frequently granted through surface-functionalization with contact-killing moieties or delivery or biocidal agents blended with the polymer matrix. These methods have drawbacks which bulk-functionalization can overcome. Quaternary ammonium compounds with various alkyl tail lengths were functionalized onto a dithiol monomer for polymerization with a novel alkyl propiolate monomer into degradable thiol-yne polymers with tunable mechanical properties. Tensile properties, cytocompatibility, and antimicrobial activity of these polymers were evaluated to assess their use as elastic biomaterials. Degradable, Mechanically Tunable Tissue Adhesives from Phosphonate-Functionalized Thiol-yne Elastomers. Tissue adhesives are biomaterials used to close skin lacerations, bind bone fragments, and form strong bonds between artificial joint replacements and bone. Commercial tissue adhesives are limited to toxic cyanoacrylates for soft tissue repair and non-adhesive, non-degradable poly(methyl methacrylate) bone cement. A novel thiol-yne elastomer was synthesized with polypropylene glycol segments added to improve solubility in clinically relevant solvents. A phosphonate-functionalized dithiol monomer was also synthesized to see if ionic interactions with the mineral composites in bone could be utilized to improve adhesion. Synthesis and Characterization of Elastic Sulfonate-Functionalized Thiol-yne Polymers for Conductive Composites. Flexible and elastic electronics are a heavily researched field with applications in medicine and technology. Soft, degradable, and elastic materials are needed which can provide both ionic and electrical conductivity. Sulfonate-functionalized thiol-yne elastomers were synthesized and tested for their hy (open full item for complete abstract)

Committee: Matthew Becker (Advisor); Andrey Dobrynin (Committee Member); Kevin Cavicchi (Committee Member); Xiong Gong (Committee Member); Yu Zhu (Committee Member) Subjects: Polymer Chemistry; Polymers

Doctor of Philosophy, University of Akron, 2018, Polymer Science

Sutures and staples are an integral part of surgeries and also the gold standard for surgical closure techniques. Additionally, in the case of orthopedic surgeries, metallic implants like plates, pins or screws are usually inserted as bone grafts. However, these techniques are quite invasive in nature, may cause wound dehiscence, secondary tissue damage, microbial infection, poor cosmetic outcome and more importantly discomfort to the patient. In some cases, the patient has to undergo another surgery for removal or replacement of sutures or bone grafts. These shortcomings have led to an urgent need to develop alternative, less invasive surgical closure techniques. Use of tissue adhesives for wound closure is an attractive alternative over the invasive methods owing to ease of preparation and application, strong adhesion and gradual degradation with tissue reconstruction. However, their toxic degradation products and potentially harmful cross-linking strategies have limited their medical applications. Recently, biomimetic adhesives have become a popular choice for application as tissue adhesives. Biomimetic adhesives are inspired from examples of adhesion in nature like mussels, sandcastle worms, barnacles, caddisflies, geckos and spiders to name a few. The adhesion characteristics and adhesive properties of mussels are of particular interest due to their strong wet and reversible adhesion, steadfast hold under variation in temperature, pH and water currents. The mussel adhesive is rich in polyphenolic protein - 3,4-dihydroxyphenylalanine (DOPA). The catechol functionality in DOPA is assumed to be the source of strong underwater adhesion in mussels. In this work, we have synthesized a catechol functionalized ethanol soluble poly(ester urea) (poly(CA-Ser-co-Leu-co-PPG) copolymer for soft tissue application. Incorporation of 20 mol% PPG units in the polymer backbone facilitates ethanol solubility making these adhesives clinically relevant. The polymer was characteri (open full item for complete abstract)

Committee: Matthew Becker Dr. (Advisor); Ali Dhinojwala Dr. (Committee Chair); Chrys Wesdemiotis Dr. (Committee Member); Mesfin Tsige Dr. (Committee Member); Bryan Vogt Dr. (Committee Member) Subjects: Polymer Chemistry

Doctor of Philosophy, Case Western Reserve University, 2017, Macromolecular Science and Engineering

This dissertation focuses on the design and fabrication of different cellulose nanocrystals (CNCs) polymer nanocomposites, with the goal of impacting the structure-property relationship between CNCs and the CNCs/matrix interactions through the surface functionalization of the CNCs with different chemical functional groups. Chapters 2-4 focus on how CNCs from sea tunicates (t-CNCs) functionalized with different chemical moieties affect the mechanical properties of the resulting nanocomposite. First (Chapter 2), t-CNCs were functionalized with lower critical solution temperature (LCST) responsive poly(oligoethylene glycol)monomethyl ether (meth)acrylates, which were incorporated into a poly(vinyl acetate) (PVAc) matrix to create reversible, thermal stiffening nanocomposites. When placed in water below the LCST the nanocomposites are soft, however, when placed in water above the LCST the nanocomposites stiffened as a result of the collapse of the grafted polymer chains allowing the engagement of t-CNCs nanorods. Secondly (Chapter 3), t-CNCs were used as fillers by functionalizing the surface with carboxylic acid moieties which aided in its dispersion in solvents such as N-methyl-2-pyyrolidone (NMP). The dispersion was further used in the synthesis of polyimide aerogels which demonstrated improved physical and mechanical properties as well as thermal stability with the incorporation of t-CNCs as a filler. Lastly (Chapter 4), by functionalizing the surface of t-CNCs with carboxylic acid and amine moieties, t-CNCs were demonstrated to be electrically active. Applying electric current across aqueous solutions of such t-CNCs, resulted in the fabrication of aligned micron-sized t-CNC fibers. Electrically aligned fiber composites with collagen were fabricated by matching the carboxylic acid/amine ratio of t-CNC and collagen. These aligned nanocomposite fibers demonstrated improved mechanical properties with higher contents of t-CNCs. Chapter 5 highlights the isolation of (open full item for complete abstract)

Committee: Stuart Rowan (Committee Chair); LaShanda Korley (Committee Member); David Schiraldi (Committee Member); Ozan Akkus (Committee Member) Subjects: Chemistry; Materials Science; Polymer Chemistry; Polymers

Master of Science, University of Akron, 2015, Engineering

The increasing demand for repositionable adhesive materials has developed a big interest among the scientific and industrial community, electrospun nanofibers has been introduced to the adhesion world as a new material that can provide repositionable dry adhesion. Adhesion tests were carried to the material, and it was found a unique combination in the adhesive properties presenting a shear adhesion of 29.44 N/cm2 and a peel strength of 0.06 and 0.01 N/cm2 for 90° and 180° angles respectively. It was found that the morphology of the electrospun nanofibers and the porosity of the fiber membrane has an important role into the delamination process along with the interaction between the electrospun fibers and the surface morphology of the substrate. This research work aims to study how this novel adhesive material delaminates and the factors involved in the delamination process.

Committee: Shing-Chung "Josh" Wong Dr. (Advisor); Srivatsan Tirumalai Dr. (Committee Member); Chang Ye Dr. (Committee Member) Subjects: Mechanical Engineering

PhD, University of Cincinnati, 2008, Engineering : Materials Science

With the demanding nature of the technology today, scientists are looking for new materials in order to decrease the cost, increase the efficiency of the use of the materials, and decrease time-consuming steps in order to increase the speed of production. New materials are being studied to decrease the weight of cars, planes and space vehicles; surface properties are being modified to decrease the drag coefficient; new technologies are being introduced for speeding up applications in production and assembly lines. In this research we address the needs of different technological applications from a conductivity perspective. In the first part of the thesis, the synthesis of soluble conducting polymers in order to make them more processable for potential electronic and photovoltaic applications is presented. Soluble conducting polymers of 3-hexylthiophene, 3-octylthiophene, 3-decylthiophene and 3-dodecylthiophene were synthesized electrochemically and thus, doped during synthesis. It was found that the conductivities; molecular weights and degrees of polymerization of the polymers strongly depend on the side chain's length. The substitution of alkyl side chains decreases the reactivity of the growing chain, and with an increasing side-chain length, all of these properties show a decrease. The hexyl substituent, being the shortest of the four side chains, causes the least distortion in the background, has the highest conjugation, and has the highest shift in the UV spectrum when it polymerizes. As the length of the side chain increases, the shift in the UV spectrum decreases, too. Decrease in the π-stacking, conjugation and delocalization decreases the conductivity. This gives the material an opportunity to be used in photovoltaic applications. In the second part of the thesis, a conducting adhesive formulation that eliminates the need for heat or other expensive and rather bothersome application methods to activate the adhesive is investigated. Using the quick setting (open full item for complete abstract)

Committee: Stephen Clarson (Advisor); Gregory Beaucage (Committee Member); Jude Iroh (Committee Member); Rodney Roseman (Committee Member) Subjects: Chemical Engineering; Chemistry; Materials Science; Plastics; Polymers

Master of Science, The Ohio State University, 2011, Dentistry

Previous research has shown that new technology in adhesive dentistry improves the performance of all-ceramic restorations. However, the major reason for failure of these restorations remains the occurrence of fractures. The overall objective of this research project was to investigate the influence of cement on the survival of all-ceramic restorations. A preliminary study was performed to evaluate the influence of the cement as a supporting structure on the survival of a simulated all-ceramic restoration. A trilayer simulation of a model restoration subjected to a clinically relevant condition of functional mastication was used. The results from the preliminary study showed that adhesively bonded specimens had higher survival rates than those conventionally cemented and that one of the adhesive cements had a significant higher survival rate than the other. Based on results from the preliminary study, three other studies were performed to investigate why adhesive cementation improves the performance of all-ceramic restorations. Results from these studies showed: (1) Resin cements had fewer defects or were void-free at the ceramic-cement interface of our ceramic model, while conventional cements showed areas of voids at the this interface. (2) The resin cement had no influence on ceramic sensitivity to slow crack growth (SCG). (3) While the actual mechanism for resin strengthening could not be determined, it may involve the formation of a more durable bond at the ceramic/cement interface.

Committee: Robert Seghi DDS,MS (Advisor); William Brantley PhD (Committee Member); Noriko Katsube PhD (Committee Member) Subjects: Dentistry

Doctor of Philosophy, University of Akron, 2007, Polymer Engineering

Epoxy/Ni adhesives can be used as integrated circuit (IC) packaging materials due to their lower cost than epoxy/Ag adhesives with acceptable electrical conductivity. In this study, epoxy/Ni adhesives were prepared and filled into multi-layer hole structures of novel design, a prototype of potential electronic components in circuit boards, to study effects of the hole structure geometry on a component's electrical resistance. An empirical relationship between the contact resistance, hole diameter, and plate thickness was proposed, together with Ohm's law, to describe effects of the geometry on electrical resistance in generic circuits. Stable and unstable capillary flows of highly filled epoxy/Ni suspensions, chemorheological behaviors, and yield behaviors of moderately filled epoxy/Ni suspensions, were also investigated to potentially relate to electrical conduction behaviors and processing of prototypes in generic circuits. Lower resin viscosity and shear rates enhance the flow instabilities and polymer binder filtering, and incorporation of Ni nanopowders promotes a stable flow, whereas occurrence of particle agglomerates somewhat nullifies this advantage. Similar phenomena occur for adhesives during cure, and the rheological behavior changes as cure proceeds. Additionally, strong nonlinearity and non-Newtonian flow behaviors were observed during cure. A comprehensive model, as well as its modified form, was proposed to describe the combined effects of the shear rate, resin conversion, filler volume fraction, and temperature on chemoviscosity. Yield behaviors of moderately filled epoxy/Ni suspensions were studied as well. Effects of the preshear, resin viscosity, temperature, particle size, as well as different methods for yield stress determination, were examined. Finally, the shear degradation of epoxy/Ni adhesives during cure was discussed.

Committee: Erol Sancaktar (Advisor) Subjects:

Doctor of Philosophy, University of Akron, 2006, Polymer Science

We have studied the contact interface between elastomeric poly(dimethyl siloxane) (PDMS) lenses with various solid surfaces during adhesion and friction using IR-visible sum frequency generation spectroscopy (SFG). SFG in total internal reflection (TIR) geometry can be used to determine molecular structure at the polymer/solid and polymer/polymer contact interfaces. It is a nonlinear optical technique, which detects the orientation and density of molecules at interfaces. In this study, we have designed a novel approach to couple SFG with adhesion and friction experiments. The solid surfaces were chosen to be octadecytrichlorosilane monolayer (OTS), poly(vinyl n-octadecyl carbamate-co-vinyl acetate) (PVNODC), polystyrene (PS), poly(n-butyl methacrylate) (PnBMA), and poly(n-propyl methacrylate) (PnPMA). In the first part of the research, we have concentrated on the importance of characterizing the static contact interface in relation to adhesion. Our results for the OTS in contact with oxygen plasma treated PDMS show surprising surface restructuring, which results in adhesion hysteresis. The short PDMS chains generated during plasma treatment are locally confined and are as strongly ordered as OTS. SFG spectra from other surfaces (sapphire substrates and fluorinated monolayers (FC)) indicates that short PDMS chains require not only confinement but also an ordered template provided by the methyl groups of OTS. In the second part, we have studied the sliding contact interfaces of various polymers with PDMS. The friction forces between PDMS lenses and glassy PS are about four times higher than PDMS sliding on crystalline well-packed PVNODC surfaces. This cannot be explained by the difference in adhesion energy or hysteresis. The in-situ SFG measurements indicate local interdigitation during contact, which is evident from the change in orientation of PS phenyl groups upon mechanical contact and during sliding compared to that at the PS surface. Such a local penetratio (open full item for complete abstract)

Committee: Ali Dhinojwala (Advisor) Subjects: Chemistry, Polymer