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Materials Chemistry

University of Massachusetts Amherst

2015

Articles 1 - 14 of 14

Full-Text Articles in Physical Sciences and Mathematics

Studying Nanoparticle/Cell And Nanoparticle/Biosurface Interaction With Mass Spectrometry, Singyuk Hou Nov 2015

Studying Nanoparticle/Cell And Nanoparticle/Biosurface Interaction With Mass Spectrometry, Singyuk Hou

Masters Theses

Nanoparticles (NPs) have been used widely in various fields ranging from biomedical applications to life science due to their highly tunable properties. It is essential to understanding how NPs interact with biological systems of interest, therefore, analytical platforms to efficiently track NPs from cell to animal level are essential. In this thesis, laser desorption ionization mass spectrometry (LDI-MS) and inductively-coupled plasma mass spectrometry (ICP-MS) has been developed and applied to quantify NP/cell and NP/biological surface interactions. These two methods provide fast, label-free and quantitative analysis. New capability of LDI-MS to differentiate cell surface-bound and internalized NPs were established and ICP-MS …

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Inkjet Printing For Biosensing And Security Applications, Brian Creran Nov 2015

Inkjet Printing For Biosensing And Security Applications, Brian Creran

Doctoral Dissertations

The adaptation of inkjet printing technology has recently been used to create controlled high throughput micro- and nano-scaled structures. Coupling this technique with gold nanoparticles in our research has produced new platforms for biosensors, chemical patterning, and anti-counterfeiting applications. In this presentation, we will highlight promising fabrication strategies including the development of test strips for the determination of bacteria in drinking water as well as the use of patterned nanoparticles for security applications.

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Impact Of Fabrication Parameters On The Internal Structure Of Poly(3-Hexylthiophene) Nanoparticles, Dana Desiree Algaier Nov 2015

Impact Of Fabrication Parameters On The Internal Structure Of Poly(3-Hexylthiophene) Nanoparticles, Dana Desiree Algaier

Doctoral Dissertations

Morphological control of organic functional materials is central to understanding and improving upon current technologies. The ability to create hierarchical assemblies with purposeful design from nano to meso scale has remained largely unattainable. This body of work aims to provide a foundation for creating nanoscale domains of poly (3-hexylthiophene) (P3HT) that can be used as building blocks to larger scale assemblies. We present a method for the fabrication of P3HT nanoparticles on the ability to vary the particle size and more importantly, the internal structure. We have identified the oil phase and surfactant as parameters able to influence the nature …

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From Molecular Scale To Mesoscale: Establishing Structural Control Organic Photovoltaics Using Organic Nanoparticles, Timothy S. Gehan Nov 2015

From Molecular Scale To Mesoscale: Establishing Structural Control Organic Photovoltaics Using Organic Nanoparticles, Timothy S. Gehan

Doctoral Dissertations

Organic photovoltaic devices use an active layer of organic materials that absorbs light and creates free charges to generate electricity. Such organic photovoltaics have many desirable properties as the final devices can be very lightweight, thin, flexible, have low manufacturing costs, and be semitransparent. These properties make them particularly advantageous for myriad of applications: e.g., use on non-planar surfaces, as tinted coatings on windows, any use for charging low power devices. One of the biggest problems preventing organic photovoltaics from being commercialized is controlling the packing of the organic materials within the active layer from the molecular scale through the …

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Conjugated Polymers In Thermoelectric Composites And Small Molecules For High Light Absorptivity, Murat Tonga Nov 2015

Conjugated Polymers In Thermoelectric Composites And Small Molecules For High Light Absorptivity, Murat Tonga

Doctoral Dissertations

Over the past several decades with increasing of global energy demand, thermoelectric materials have gained considerable attention due to their unique ability to directly convert heat to electricity. In addition to inorganic semiconductors, polymers are potential candidates for high-performance thermoelectric applications due to their intrinsic advantages such as low thermal conductivity, solution processability, and roll-to-roll production, lightweight, and flexible thermoelectric modules. This thesis provides an insight into the emerging field of organic thermoelectrics, more specifically, thermoelectric power generation based on the composites of conducting polymers (MEH-PPV, P3HT and PEDOT:PSS) and carbon nanotubes (SWNT, SWNT-COOH, SWNT-OH and MWNT). A substantial portion …

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Morphology Evolution Mechanisms Of Low Band Gap Polymer-Based Photovoltaics, Sunzida Ferdous Nov 2015

Morphology Evolution Mechanisms Of Low Band Gap Polymer-Based Photovoltaics, Sunzida Ferdous

Doctoral Dissertations

An optimal nanoscale phase separation between the donor (generally, a conjugated polymer) and the acceptor (generally, a fullerene derivative) materials is one of the major requirements for obtaining high efficiency organic photovoltaic (OPV) device. Recent methods of controlling such nanostructure morphology in a bulkheterojunction (BHJ) OPV device involve addition of a small amount of solvent additive to the donor and acceptor solutions. The idea is to retain the acceptor materials into the solution for a longer period of time during the film solidification process, thus allowing the donor material to crystallize earlier. The ultimate morphology resulting from the solvent casting …

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Polymer And Fullerene Zwitterions: From Synthesis To Solar Cells, Zachariah A. Page Nov 2015

Polymer And Fullerene Zwitterions: From Synthesis To Solar Cells, Zachariah A. Page

Doctoral Dissertations

This thesis describes the synthesis and applications of hydrophilic conjugated polymers and fullerenes containing dipole-inducing pendent groups. The pendent groups include tertiary amines, sulfobetaine (SB) zwitterions, quaternary ammoniums, and sulfonates, providing solubility in polar solvents. Particular emphasis is placed on zwitterions functalized structures. Suzuki-Miyaura (SM) and Horner-Wadsworth-Emmons (HWE) coupling reactions proved valuable for the preparation of the hydrophilic conjugated polymers, while the Prato reaction afforded the functional fulleropyrrolidines. Ultraviolet photoelectron spectroscopy (UPS) probed the interactions between the hydrophilic conjugated polymers and conductive metal substrates. In particular, UPS revealed that conjugated polymer zwitterions (CPZs) substantially reduce work function (Φ) of metals, …

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Responsive Supramolecular Assemblies Based On Amphiphilic Polymers And Hybrid Materials, Longyu Li Nov 2015

Responsive Supramolecular Assemblies Based On Amphiphilic Polymers And Hybrid Materials, Longyu Li

Doctoral Dissertations

The design and synthesis of responsive supramolecular assemblies are of great interest due to their applications in a variety of areas such as drug delivery and sensing. We have developed a facile method to prepare self-crosslinking disulfide-based nanogels derived from an amphiphilic random copolymer containing a hydrophilic oligo-(ethylene glycol)-based side-chain functionality and a hydrophobic pyridyl disulfide functional group. This thesis first provides a concept of studying the influence of Hofmeister ions on the size and guest encapsulation stability of a polymeric nanogel. The size and core density of nanogel can be fine-tuned through the addition of both chaotropes and kosmotropes …

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Design And Application Of Organic Electronic Materials: Pendant Tuning In Polymeric And Molecular Systems, Jonathan S. Tinkham Aug 2015

Design And Application Of Organic Electronic Materials: Pendant Tuning In Polymeric And Molecular Systems, Jonathan S. Tinkham

Doctoral Dissertations

Designing and synthesizing materials for use in organic electronic materials requires fine control over their optical and electronic properties. Variations through substitution can be used to tune solubility and electronic properties, but this can result in degradation of other properties. Substitution with orthogonal pendant groups in both molecular and polymeric systems has the potential for allowing tunability while decreasing the perturbation of other desirable properties of the parent system. This idea was explored through experimental and computational work. Computational modelling was used to understand and predict the properties of molecular and polymeric systems to narrow the wide number of choices …

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Tunable Photonic Multilayers From Stimulus-Responsive, Photo-Crosslinkable Polymers, Maria C. Chiappelli Aug 2015

Tunable Photonic Multilayers From Stimulus-Responsive, Photo-Crosslinkable Polymers, Maria C. Chiappelli

Doctoral Dissertations

This dissertation describes the synthesis of photo-crosslinkable copolymers and their utilization for the fabrication and testing of tunable and responsive one-dimensional (1D) photonic multilayers. Photonic multilayers exhibit structural color due to the interference of incident light at layer interfaces, providing a convenient route towards optically responsive materials that do not rely on potentially light- or oxygen-sensitive chromophore-containing pigments and dyes. A fabrication technique based on sequential spin-coating and crosslinking of photo-crosslinkable polymers is used to assemble tunable and responsive photonic multilayers. Chapter One introduces the fundamental underlying principles of 1D photonic structures and explores their importance in a variety of …

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Catalytic Methane Dissociative Chemisorption Over Pt(111): Surface Coverage Effects And Reaction Path Description, Inara Colon-Diaz Mar 2015

Catalytic Methane Dissociative Chemisorption Over Pt(111): Surface Coverage Effects And Reaction Path Description, Inara Colon-Diaz

Masters Theses

Density functional theory calculations were performed to study the dissociative chemisorption of methane over Pt(111) with the idea of finding the minimum energy path for the reaction and its dependence on surface coverage. Two approaches were used to evaluate this problem; first, we used different sizes of supercells (2x2, 3x3, 4x4) in order to decrease surface coverage in the absence of pre-adsorbed H and CH3 fragments to calculate the energy barriers of dissociation. The second approach uses a 4x4 unit cell and surface coverage is simulated by adding pre-absorbed H and CH3 fragments. Results for both approaches show …

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Design, Synthesis, And Bio Relevant Applications Of Zwitterionic Amphiphilic Macromolecular Assemblies, Rajasekhar Reddy Rami Reddy Mar 2015

Design, Synthesis, And Bio Relevant Applications Of Zwitterionic Amphiphilic Macromolecular Assemblies, Rajasekhar Reddy Rami Reddy

Doctoral Dissertations

Supramolecular nanoassemblies capable of reducing non-specific interactions with biological macromolecules, such as proteins, are of great importance for various biological applications especially for targeted drug delivery therapeutics. Recently, zwitterionic materials have been shown to reduce non-specific interactions with biomolecules, owing both to their charge neutrality and their ability to form strong hydration layer around zwitterions via electrostatic interactions. This dissertation focuses on design, synthesis, thorough characterization, and applications of zwitterionic amphiphilic dendrimers and polymeric materials. Firstly, A new triazole-based zwitterionic moiety was conceived and incorporated as the hydrophilic functionality in facially amphiphilic dendrons. Self-assembly characteristics and the structural and functional …

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Functional Nanostructures From Nanoparticle Building Blocks, Jimmy Lawrence Mar 2015

Functional Nanostructures From Nanoparticle Building Blocks, Jimmy Lawrence

Doctoral Dissertations

Advances in the synthetic strategies of engineered nanomaterials, multifunctional molecules and polymers have opened pathways for the development of functional nanomaterials having unique optoelectronic, mechanical, and biological properties. By designing the chemistry of surface ligands, the organic interface of nanoparticles, one can further the versatility and utilization of engineered nanomaterials, opening pathways for breakthroughs in sensing, catalysis, and delivery using nanomaterials. This thesis describes the synthesis and characterization of small molecule and polymer ligand functionalized inorganic nanoparticles (e.g., metal, semiconducting). Embedding specific chemical functionality into the ligand periphery of nanoparticles enables the resulting functional nanoparticles to react selectively …

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Aggregation And Interfacial Behavior Of Charged Surfactants In Ionic Liquids, Lang Chen Mar 2015

Aggregation And Interfacial Behavior Of Charged Surfactants In Ionic Liquids, Lang Chen

Doctoral Dissertations

Room-temperature ionic liquids (ILs) exhibit a unique set of properties, leading to opportunities for numerous applications such as green solvents, batteries and lubricants. Their properties can be greatly tuned and controlled by addition of surfactants. It is therefore critical to obtain a better understanding of the aggregation and interfacial behavior of surfactants within ILs. Firstly, the phase diagram and aggregation isotherms of surfactants in several distinct ILs were investigated by solubility and tensiometry. A connection between solubility of the surfactant and the physical properties of the underlying ionic liquid was established. We found that the interfacial energy was crucial in …

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