MICRO AND NANO R2R EMBOSSING OF EXTRUDED POLYMERS

This dissertation presents a process for directly imprinting or embossing extruded polymers as an advancement in roll-to-roll (R2R) embossing methods that avoids the problems of converting preformed films, increases throughput, and reduces costs. A proof-of-concept R2R apparatus was designed and constructed for directly embossing extruded polymer, and experimental results were evaluated. This laboratory scale R2R apparatus employed a thin metal ribbon belt mold with micro or nano scale features in a calendering setup, with a close coupled induction heating (IH) coil to preheat the ribbon mold above glass transition temperature (Tg) of the polymer, prior to contact with the extrudate at the nip of the calender. This allowed the melted polymer to fully fill the mold patterns before starting to solidify. The thin ribbon mold rapidly conducted heat to the calender roller, providing an effective cooling stage. Microscale and nanoscale features were imprinted directly onto extruded polymer film at a rate of 10 to 12 meters per second, three to over one hundred times the throughput of current R2R processes and orders of magnitude faster than planar processes. Metal ribbon mold belts with nano features were needed to test the direct embossing of extruded polymers at the nano scale. Three different avenues were taken to make such ribbon belts. First, preset nickel alloy molds were obtained. A master mold of the Book of Leviticus with letters 6 µm in width, 6 to 9 µm tall and 60-170 nm high and a nickel alloy DVD master mold with track pitch of 740 nm and 105 nm deep Pits between 400 nm and 1900 nm long. These were welded into stainless steel ribbon belts to form belt molds. Second, a process was developed using base forms or mandrels for metal-forming nickel ribbon belt molds with test patterns that included gratings from 70 to 500 nm and pillars having diameters of 1 µm, 700 nm, 500 nm and 350 nm. Third, an investigation of metal glass (MG) as a candidate mold material was undertaken and a laboratory scale mechanism was designed and constructed to emboss metal glass surfaced rollers thermally

Application of Ni-P Alloys to A Mold Material for Thermal Imprinting on Pyrex Glass

The author developed a low-cost mold for imprinting on Pyrex glass. The mold was fabricated by the processing of micro-/nano-patterns made by FIB etching on an amorphous Ni-P alloy layer electroless-plated on Cu/Cr/Si, Ni/Ti/Si, and Inconel-600 substrates, followed by a thermal treatment, since a 400 °C for 3 h thermal treatment was known to increase the hardness of a Ni-P layer. The wt.% of P was changed to 4, 8, and 16; and scratch test and imprint experiments on the Pyrex glass showed Ni-16P/polished-Inconel-600 mold giving a best result. We also successfully demonstrated the making of line/space patterns, microlenses, and AIST logos on Pyrex glass. It was also experimentally proved that a Ni-P alloy can be used as a mold material to imprint on Pyrex glass at high temperature around 640 °C under vacuum without employing any release agent

Fabricating microfluidic devices in polymers for bioanalytica applications

The research presented in this document focuses on the fabrication, characterization and application of microfluidic systems fabricated in poly(methyl methacrylate) (PMMA) with the emphasis focused on the fabrication processing steps. Microfluidic devices were produced in PMMA using X-ray lithography. The fabrication methods investigated were sacrificial mask, polyimide membrane mask and embossing techniques. PMMA microfluidic devices fabricated using X-ray lithography were characterized using scanning electron microscopy (SEM) and optical microscopy, while analytical techniques such as electroosmotic flow determination, separations, and fluorescent microscopy were used to characterize fluid transport in these devices. A novel method for the heat annealing of PMMA to PMMA to create a closed system is described. Characterization of this technique was carried out by optical microscopy and scanning electron microscopy. The manufacturing techniques utilized in producing mold inserts for hot embossing and injection molding is discussed as well. Both the mold insert and devices produced from the inserts were characterized using scanning electron microscopy. Devices produced can be used to perform a number of analytical techniques including single molecule detection and fluorescence lifetime monitoring. The primary goal of this research was to develop molding tools consisting of high-aspect-ratio microstructures using robust and reproducible processing steps

Development of self-cleaning polymeric surfaces using polymer processing systems for application to high-voltage insulators

Herein, polymer processing systems are used to fabricate superhydrophobic high-temperature vulcanized (HTV) silicone rubber surfaces by direct replication. HTV silicone rubber is one of the main polymeric housing materials used in high-voltage insulators. The selected polymer processing techniques are compression molding and injection molding.The direct replication approach requires that a template or insert having the desired surface patterns be replicated onto a target polymer surface via a polymer processing. The appropriate micro-nanostructures, required for achieving ultra-water-repellency, were created on the insert materials (an aluminum alloy) using a wet-chemical etching method. As a flawless demolding is essential to acquire desirable replication quality, an antistiction coating was applied to the insert surfaces prior to the molding process to ensure the thorough removal of the silicone rubber during the demolding. The resulting silicone rubber surfaces possessed micro-nanostructures producing a water contact angle (WCA) of >160° and a contact angle hysteresis (CAH) of <3°. The surface roughness of the aluminum inserts was optimized at HCl concentrations of 15 wt.%. The self-cleaning properties of the produced ultra-water-repellent silicone rubber surfaces were rigorously investigated to ensure a self-cleaning surface at real outdoor imitated conditions. The presence of air pockets in between the surface asperities produced the Cassie-Baxter regime. The consistency of these air pockets is crucial for attaining the self-cleaning properties. A series of tests, including droplet impact, water-jet impact, trapped air layer, and severe droplet contact tests were conducted to confirm the stability of the Cassie-Baxter regime. A comprehensive series of self-cleaning experiments involving both suspended and non-suspended contaminants, e.g., kaolin, carbon black, and silica as well as contaminant-applying methods, e.g., dropwise, spraying, wet or dry contamination were performed. Self-cleaning tests were organized from less severe, i.e., non-suspended contamination tests, to severe, i.e., the wet suspended contamination test, to most severe, i.e., the dry suspended contamination test. Due to their ultra-low CAH, the produced surfaces demonstrated favorable self-cleaning properties against the various types of contaminants and the different means of contaminant application. The produced surfaces retained their water repellency following the application of the contaminants and successful cleaning of the surfaces, thereby verifying the self-cleaning performance and resistance of the fabricated superhydrophobic silicone rubber surfaces. The anti-icing properties (delayed ice formation) and de-icing properties (reduced ice adhesion strength) of the produced surfaces were evaluated. Two types of icing (atmospheric glaze and bulk ice) were considered to accumulate ice on the surfaces. The well-known ice adhesion measurement techniques, i.e., the centrifuge adhesion and push-off tests were employed to provide quantitative comparisons of the ice adhesion strength of the produced surfaces. The produced surfaces significantly delayed ice formation and reduced the ice adhesion strength. To rigorously assess the durability of the produced surfaces, a comprehensive series of experiments that covered a wide range of real-life conditions were carried out. In some cases, where the water repellency was lost, the silicone rubber surfaces demonstrated a satisfactory recovery of their anti-wetting properties. Given the importance of replication quality in the direct replication of micro-nanostructures and the role of micro-nanostructures in the formation of superhydrophobic and icephobic surfaces, the effect of processing parameters on the superhydrophobicity, icephobicity, and replication quality in the compression molding of silicone rubber surfaces were evaluated. Curing time, mold temperature, molding pressure, and part thickness were assessed via response surface methodology to determine the optimal processing parameters. Molding pressure and part thickness were revealed as two main influencing parameters in the superhydrophobic properties. The crosslink density of the fabricated silicone rubber samples, however, was found to be significantly affected by curing time and mold temperature. Replication quality was determined for various molding pressures and part thicknesses. There was an optimal molding pressure value at each part thickness level to obtain the best replication quality. Surfaces having the highest replication quality showed the longest freezing delay reflecting their potential use as anti-icing surfaces. Although all superhydrophobic surfaces offered potential icephobic properties, identifying the influential parameters controlling ice adhesion was more complicated. As this PhD project is part of an industrial-academic collaboration, the results obtained in the laboratory experiments were used for implementation in the industry (K-Line Insulators Limited). This step includes the use of aluminum and stainless-steel inserts. Using the injection molding system available at K-Line Insulators Ltd., silicone rubber insulators having superhydrophobic properties were produced successfully. The industrial partner provided facilities to modify its mold to produce superhydrophobic insulators in an industrial scale. Dans cette thèse, les systèmes de transformation des polymères sont utilisés pour fabriquer des surfaces superhydrophobes de caoutchouc de silicone vulcanisé à haute température (HTV) à partir d’une réplication directe. Le HTV est l’un des principaux matériaux polymères utilisés dans la fabrication des isolateurs à haute tension. Les systèmes considérés sont des procédés de moulage par compression et de moulage par injection. L'approche de réplication directe nécessite un modèle ou un insert ayant les structures de surface souhaitée à répliquer sur la surface du polymère. Les micronanostructures appropriées pour obtenir la non-mouillabilité de la surface ont été créées sur les matériaux d'insert (alliage d'aluminium) en utilisant un procédé de gravure chimique. Comme un démoulage sans défaut est essentiel pour obtenir la qualité de réplication souhaitable, un revêtement antiadhésif est appliqué sur les surfaces de l'insert avant le processus de moulage afin d’assurer l'élimination complète du caoutchouc de silicone lors du démoulage. Les surfaces de caoutchouc de silicone développées possédaient des micronanostructures produisant un angle de contact eau (WCA) de > 160 ° et une hystérésis angle de contact (CAH) de < 3 °. La rugosité optimale de surface des inserts en aluminium est obtenue à une concentration massique de HCl de 15%. Les propriétés autonettoyantes des surfaces produites ont été rigoureusement étudiées pour assurer que ces propriétés autonettoyantes demeuraient efficaces dans des conditions extérieures réelles. La présence de poches d'air entre les aspérités de surface est responsable de la formation du régime de Cassie-Baxter. La consistance de ces poches d’air est cruciale pour obtenir des propriétés autonettoyantes. Par conséquent, une série d’essais ont été effectués pour confirmer la stabilité du régime Cassie-Baxter. Ensuite, une série complète d'expériences de propriétés autonettoyantes a été réalisée en impliquant des contaminants en suspension et non suspendus (non dispersés) utilisant divers matériaux (par exemple, le kaolin, le noir de carbone, la silice, etc.) et des méthodes d'application de contaminants (par exemple, goutte à goutte, pulvérisation, contaminants humides ou secs) ont été effectuées. Les tests d’autonettoyage ont été organisés, du test le moins sévère, c’est-à-dire de la contamination non suspendue (non dispersée), au test plus sévère, c’est-à-dire de la contamination en suspension humide, et se terminant par le test le plus sévère, à savoir la contamination en suspension sèche. En raison du CAH ultra-bas, les surfaces produites ont montré des propriétés autonettoyantes favorables contre les différents types de contaminants et de différents moyens d'application de contaminants. Les surfaces produites ont conservé leurs propriétés répulsives après l'application des contaminants et après le nettoyage des surfaces, permettant ainsi de vérifier les performances d'autonettoyage et la résistance des surfaces en silicone superhydrophobe fabriquées. Les propriétés anti-givrantes (la formation retardée de la glace) et les propriétés glaciophobes (la force d'adhérence réduite de la glace) des surfaces produites ont été évaluées. Les surfaces produites sont exposées à la formation de deux types de givrage. Les techniques bien connues de mesure de l'adhésion sur la glace, à savoir le test d'adhérence par centrifugation et le test de poussée, ont été utilisées pour obtenir une comparaison précise des résultats. Les surfaces superhydrophobes produites ont considérablement retardé la formation de glace et réduit la force d'adhérence de la glace. Afin d’évaluer de manière rigoureuse les propriétés de durabilité, une série complète d’expériences a été réalisée sur les surfaces. Les expériences de durabilité ont été menées pour couvrir un large éventail d'applications réelles. En ce qui concerne la capacité attractive du caoutchouc de silicone dans la récupération des propriétés anti-mouillantes, la perte de la propriété de répulsion de l’eau a été régénérée jusqu’à un niveau satisfaisant dans certains cas. Compte tenu de l’importance de la qualité de la réplication dans la réplication directe des micronanostructures d’une part, et d’autre part du rôle des micronanostructures dans la formation de surfaces superhydrophobes et glaciophobes, les effets des paramètres de moulage par compression des surfaces en caoutchouc de silicone sur la superhydrophobicité, la glaciophobicité et la qualité de la réplication ont été évaluées. Le temps de durcissement, la température de moulage, la pression de moulage et l'épaisseur de la pièce ont été choisis comme paramètres de traitement à évaluer. La méthodologie de surface de réponse a été utilisée pour déterminer les paramètres de traitement optimaux. Bénéficiant des résultats, la pression et l'épaisseur ont été révélées comme les deux paramètres d'influence principaux des propriétés superhydrophobes. La densité de réticulation des échantillons de caoutchouc de silicone fabriqués s'est toutefois révélée être significativement affectée par le temps et la température. Les valeurs de qualité de réplication ont été déterminées en fonction de diverses pressions et épaisseurs. Il y avait une valeur de pression optimale à chaque niveau d'épaisseur pour obtenir la meilleure qualité de réplication. Il a également été observé que les surfaces présentant la meilleure qualité de réplication affichaient le plus long retard de gel de la gouttelette d’eau, ce qui représentait leur potentiel élevé d'utilisation en tant que surfaces antigivrantes. Bien que toutes les surfaces superhydrophobes aient présenté des propriétés potentiellement glaciophobes, il a été constaté que le scénario d’adhérence sur la glace était plus compliqué en termes de paramètres influents. Ce projet de doctorat fait partie d'une collaboration industrielle-académique. Les résultats obtenus en laboratoire ont été utilisés pour la mise en œuvre dans l'industrie (K-Line Insulators Limited). À cette étape, des inserts en aluminium et en acier inoxydable ont été utilisés. En utilisant le système de moulage par injection disponible chez K-Line Insulators Ltd., des isolateurs en caoutchouc de silicone ayant des propriétés superhydrophobes ont été produits avec succès. Par conséquent, le partenaire industriel fournit des installations pour modifier son moule afin de produire des isolateurs superhydrophobes à l'échelle industrielle

ULTRAVIOLET ROLL-TO-ROLL NANOIMPRINT LITHOGRAPHIC FABRICATION OF FLEXIBLE POLYMER MOULDS

Ph.DDOCTOR OF PHILOSOPH

Focused ion beam technology : implementation in manufacturing platforms and process optimisation

Process chains are regarded as viable manufacturing platforms for the production of Microand Nano Technology (MNT) enabled products. In particular, by combining several manufacturing technologies, each utilised in its optimal process window, they could benefit from the unique advantages of high-profile research technologies such as the focused ion beam (FIB) machining. The present work concerns the development of process chains and the investigation of pilot cost-effective implementations of the FIB technology in manufacturing platforms forfabrication of serial replication masters.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Focused ion beam technology: implementation in manufacturing platforms and process optimisation

Process chains are regarded as viable manufacturing platforms for the production of Microand Nano Technology (MNT) enabled products. In particular, by combining several manufacturing technologies, each utilised in its optimal process window, they could benefit from the unique advantages of high-profile research technologies such as the focused ion beam (FIB) machining. The present work concerns the development of process chains and the investigation of pilot cost-effective implementations of the FIB technology in manufacturing platforms forfabrication of serial replication masters

Micro and nano–manufacturing process chains: maturity assessment and bulk metallic glass enabled manufacturing routes

The utilisation of process chains is considered as a way forward to achieve cost effective and high throughput production of miniaturised devices. However there are no methodologies to analyse systematically process chains and thus to inform their development and design new ones for microfabrication. Thus, this research first proposes a methodology for assessing the maturity of micro and nano- manufacturing (MNM) technologies and their interfaces in process chains. The applicability and benefits of using it as a tool for assessing the maturity levels of individual processes and chains is demonstrated on existing and emerging MNM platforms. Then, to address the growing requirements for function and length scale integration (FLSI) in devices, two bulk metallic glass (BMG) enabled master-making process chains were designed and validated for serial replication of polymer components with sub-micron and micro size functional features. The empirical research proved that the use of BMG workpieces with their intrinsic atomic level homogeneity enables the integration of complementary MNM technologies for achieving FLSI in replication inserts. Furthermore, it was demonstrated that such process chains can be successfully employed for producing inserts incorporating both micro and nano- scale features that can be utilised for serial production of polymerbased FLSI devices

Advances in Micro and Nano Manufacturing: Process Modeling and Applications

Micro- and nanomanufacturing technologies have been researched and developed in the industrial environment with the goal of supporting product miniaturization and the integration of new functionalities. The technological development of new materials and processing methods needs to be supported by predictive models which can simulate the interactions between materials, process states, and product properties. In comparison with the conventional manufacturing scale, micro- and nanoscale technologies require the study of different mechanical, thermal, and fluid dynamics, phenomena which need to be assessed and modeled.This Special Issue is dedicated to advances in the modeling of micro- and nanomanufacturing processes. The development of new models, validation of state-of-the-art modeling strategies, and approaches to material model calibration are presented. The goal is to provide state-of-the-art examples of the use of modeling and simulation in micro- and nanomanufacturing processes, promoting the diffusion and development of these technologies