Plasma surface treatment is an effect method to modify the surface chemistry of a plastic substrate without affecting the nature of the substrate itself .In this there, we use high frequency SF6 plasma generated by Electron Cyclotron Resonance (ECR) to modify the surface properties of a Poly ethylene terephthalate (PET) substrate. We found that the PET surface properties were strongly related to the gas pressure, RF power and reaction time, In addition, by masking on parts of the sample surface, both by hydrophobic and hydrophilic surfaces can be obtained in a single process. The hydrophilic is formed because of large amount of oxygen atoms reacting to the masking areas of the sample surface after the sample was exposed to the atmosphere. The difference of the measured water contact angle of hydrophobic and hydrophilic surface is larger than 100 degree.

Understanding and controlling the nature of interactions at interfaces between various materials and systems has always been of interest, but with the fast development and need of new technologies it has become crucial to employ these interactions for various applications that range from biosensing of analytes in bodily fluids and the environment, to the development of bio-compatibatible and bio-mimicking surfaces that can be used to successfully couple biological systems to artificial materials and also build models for understanding biological systems better. Self-assembled monolayers (SAMs) are organized molecular assemblies that are formed by spontaneous adsorption of a compound in solution to a surface. They can change the surface properties without the need of changing the physical properties of the bulk material. Formation of SAMs on different substrates was investigated and performed in the work described in the thesis to be used in the detection of nucleic acids and enzyme inhibitors, development of surfaces with anti-adhesive and anti-microbial properties, development of surfaces for directed and patterned cell adhesion, and the construction of artificial membranes that can be used for studying the interaction of membrane proteins and the discovery of new pharmaceuticals. The surface of gold substrates was modified with alkanethiol compounds in order to attach biomolecules such as nucleic acids and proteins which allowed the modified surface to be used as a biosensor. Binding interactions were detected by electrochemical impedance spectroscopy and surface plasmon resonance. A surface resonance sensor provided a platform for the detection of DNA and RNA oligonucleotide sequences and also the detection of one-nucleotide mismatches from the hybridization these oligonucleotides. The same sensor platform, but with a different surface modification, was used to covalently attach an enzyme whose inhibitors are used as therapeutic drugs and also as pesticides and nerve agents. The sensor was able to detect two of these inhibitors, which are used in the treatments of Alzheimer's disease, at a range of concentrations. This allowed the determination of binding affinity constants for the two inhibitors. The surface of gold was modified with functional groups in order to obtain inert surfaces with anti-adhesive properties with regard to the attachment of proteins. These surfaces are of interest in generating bio-compatible medical implants that can resist rejection from the host's immune system andor the formation of bacterial biofilms. The inert property was combined with anti bacterial properties by attaching an antibiotic which is known to kill bacteria by binding to the cell membrane. Following characterization of gold surfaces by contact angle measurements, ellipsometry, grazing angle FT-IR, cyclic voltammetry and electrochemical impedance spectroscopy, the surface of glass substrates was modified with similar functional groups, by switching to a different coupling ligand for the substrate. Alkoxysilanes were used to modify the surface of glass, which can also be used to modify other materials, such as polymers and stainless steel. Gold and glass surfaces were also modified with antibodies, other proteins, and other functional groups which favored or prevented cell adhesion. This led to the ability for patterned and directed adhesion, and differentiation of several cell lines. Preparation and chemical modification of magnetic beads and the ability to modify the bead surface created the possibility to grow and trap cells in a flow-through magnetic bioreactor, which will be used for the continuous production of metabolites and growth of tissue in a three-dimensional construct. Modification of gold substrates also led to the construction of artificial phospholipid membranes, whose composition can be controlled and most importantly can be used for the insertion and characterization of membrane proteins on a two-dimensional platform. This will allow for characterization of ligand-protein and protein-protein interactions with surface characterization techniques such as surface plasmon resonance and electrochemical impedance spectroscopy. The various surface modifications and applications described in this work underscore a general theme that the surface of many different materials can be modified by using the correct functional groups for the formation of the self-assembled monolayer on the substrate surface, thus obtaining the same surface properties without the need to change the physical and chemical properties of the bulk material.

Layer-by-layer assembly has received much attention over the last fifteen years. This assembly process can be carried out using different methods including hydrogen-bonding, electrostatic, and to a lesser extent, covalent interactions. However, these assemblies are rarely seen on polyolefin substrates due to the lack of functionality on the surface. “Click” chemistry has become very popular in recent years as a means to join modular compounds together. This thesis is the first published report to use “click” chemistry as a means for layer-by-layer assembly on a polymeric substrate. By designing polymers that contain alkyne or azide groups, it is possible to assemble them layer-by-layer on a polyethylene substrate. Polymers based on tert-butyl acrylate were initially designed for use in organic solvents such as tetrahydrofuran. The copper catalyst that facilitated the 1,3-dipolar cycloaddition was air sensitive and expensive. To capture the true essence of “click” chemistry, a new system was designed based on N-isopropyl acrylamide (NIPAM)-based polymers. These polymers were water soluble and allowed for “click” chemistry to be performed in water and open to air in benign conditions. With the development of a water soluble polymer system that could be modified to contain either azide groups or alkyne groups, layer-by-layer assembly was carried out in water. A polyethylene film was modified in a series of reactions to have an alkyne-functionalized surface. The poly(N-isopropyl acrylamide)-based polymers were layered in an alternating fashion to form multilayer assemblies. A series of control reactions were also performed, showing that these layers were interconnected via triazole linkages. These assemblies were monitored by attenuated total reflectance spectroscopy. Once the layers were assembled, the polyvalent nature of the polymers allowed for further functionalization. Various surface functionalizations were established using fluorescence microscopy and contact angle analysis. By using spectroscopic and chemical means, layer-by-layer assembly on polyethylene films was proven. Control reactions showed the necessity of components for triazole formation. Therefore, layer-by-layer assembly using “click” chemistry was achieved.

Layer-by-layer assembly has received much attention over the last fifteen years. This assembly process can be carried out using different methods including hydrogen-bonding, electrostatic, and to a lesser extent, covalent interactions. However, these assemblies are rarely seen on polyolefin substrates due to the lack of functionality on the surface. “Click” chemistry has become very popular in recent years as a means to join modular compounds together. This thesis is the first published report to use “click” chemistry as a means for layer-by-layer assembly on a polymeric substrate. By designing polymers that contain alkyne or azide groups, it is possible to assemble them layer-by-layer on a polyethylene substrate. Polymers based on tert-butyl acrylate were initially designed for use in organic solvents such as tetrahydrofuran. The copper catalyst that facilitated the 1,3-dipolar cycloaddition was air sensitive and expensive. To capture the true essence of “click” chemistry, a new system was designed based on N-isopropyl acrylamide (NIPAM)-based polymers. These polymers were water soluble and allowed for “click” chemistry to be performed in water and open to air in benign conditions. With the development of a water soluble polymer system that could be modified to contain either azide groups or alkyne groups, layer-by-layer assembly was carried out in water. A polyethylene film was modified in a series of reactions to have an alkyne-functionalized surface. The poly(N-isopropyl acrylamide)-based polymers were layered in an alternating fashion to form multilayer assemblies. A series of control reactions were also performed, showing that these layers were interconnected via triazole linkages. These assemblies were monitored by attenuated total reflectance spectroscopy. Once the layers were assembled, the polyvalent nature of the polymers allowed for further functionalization. Various surface functionalizations were established using fluorescence microscopy and contact angle analysis. By using spectroscopic and chemical means, layer-by-layer assembly on polyethylene films was proven. Control reactions showed the necessity of components for triazole formation. Therefore, layer-by-layer assembly using “click” chemistry was achieved.

Indiana University-Purdue University Indianapolis (IUPUI) / A Polyvinylchloride surface was modified by coating a biocompatible, hydrophilic and antibacterial polymer by a mild surface modification method. The surface was first activated and then functionalized, followed by coating with polymer. The surface functionality was evaluated using cell adhesion, bacterial adhesion and bacterial viability for polymers with antibacterial properties. 3T3 mouse fibroblast cells were used for cell adhesion, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus were used for bacterial adhesion in the first study, Pseudomonas aeruginosa and Staphylococcus aureus were used for bacterial adhesion and antibacterial activity in the second study. Chapter 2 reports how we synthesized, immobilized and evaluated a novel hydrophilic polymer with anti-fouling properties onto surface of polyvinylchloride via an effective and mild surface coating technique. The polyvinylchloride surface was first activated by azidation as well as amination, and then tethering a newly synthesized hydrophilic and biocompatible polyvinylpyrrolidone having pendent reactive succinimide functionality onto the surface. Results show that the coated hydrophilic polymer significantly reduced the 3T3 fibroblast cell adhesion as well as the adhesion of the three bacterial species. Chapter 3 reports how we prepared, immobilized and evaluated an antibacterial and anti-fouling polymer onto polyvinylchloride surface following an efficient and simple method of surface modification. The surface coated with a terpolymer constructed with N-vinylpyrrolidone, 3,4-Dichloro-5-hydroxy-2(5H)-furanone derivative and succinimide residue was evaluated with cell adhesion, bacterial adhesion and bacterial viability. Surface adhesion was evaluated with 3T3 mouse fibroblast cells and two bacterial species. Also, antibacterial activity was evaluated by bacterial viability assay with the two bacterial species. Results showed that the polymer-modified polyvinylchloride surface exhibited significantly decreased 3T3 fibroblast cell adhesion and bacterial adhesion. Furthermore, the modified polyvinylchloride surfaces exhibited significant antibacterial functions by inhibiting bacterial growth with bactericidal activity. Altogether, we have successfully modified the surface of polyvinylchloride using a novel efficient and mild surface coating technique. The first hydrophilic polymer-coated polyvinylchloride surface significantly reduced cell adhesion as well as adhesion of three bacterial species. The second hydrophilic and antibacterial polymer-coated polyvinylchloride surface demonstrated significant antibacterial functions by inhibiting bacterial growth and killing bacteria in addition to significantly reduced 3T3 fibroblasts and bacterial adhesions.

No description available.

Laser surface modification involves rapid melting and solidification is an elegant technique used for locally tailoring the surface morphology of alumina in order to enhance its abrasive characteristics. COMSOL Multiphysics® based heat transfer modeling and experimental approaches were designed and used in this study for single and multiple laser tracks to achieve densely-packed multi-facet grains via temperature history, cooling rate, solidification, scanning electron micrographs, and wear rate. Multi-facet grains were produced at the center of laser track with primary dendrites extending toward the edge of single laser track. The multiple laser tracks study indicates the grain/dendrite size increases as the laser energy density increases resulting in multiplying the abrasive edges which in turn enhance the abrasive qualities.

No description available.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16407号 / 工博第3488号 / 新制||工||1527(附属図書館) / 29038 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 岩田 博夫, 教授 田畑 泰彦, 教授 秋吉 一成 / 学位規則第4条第1項該当

This thesis is concerned with the synthesis of diazo compounds for the introduction of various functional groups on the surface of polymers by means of carbene insertion and diazonium coupling. Characterisation and investigation of their properties were conducted. A library of functionalised polystyrene beads containing pyridine rings has been established for the coordination of metal ions and metal complexes. The pyridyl system on the surface has demonstrated its capability to bind with zinc complexes of bis(thiosemicarbazones) and release the corresponding copper complexes upon transmetallation. A spiropyran derivative has been introduced onto the surface of polystyrene and polyethylene terephthalate. The chromophore on both polymers exhibited photoswitchability as determined from colour change and wettability. Polystyrenes with either pyridine or spiropyran units have been investigated for reversible immobilisation of bioactive species. Materials coated with penicillin V gave significant inhibition zones in antibacterial assays, showing efficacy in drug delivery. Finally, a range of diazo compounds with different substituents has been synthesised and their thermal stabilities have been assessed by differential scanning calorimetry technique.