The intention of this project is to research the potential of emergent technologies for developing sustainable composites for the building industry. It is divided into three parts: Part 1 Identifies emergent practices which are being applied to the development of new sustainable building prototypes such as developments using nanotechnologies, the influence of biomimetics, the development of intelligent interactive systems and the use of digital technologies to generate complex cellular structural systems. Part 2 Outlines existing processes involved in selecting and manufacturing prototypes, as many existing processes have been opportunistically applied to emergent practices to generate innovative sustainable prototypes. Part 3 By synthesising the research gathered in the previous parts of this thesis, this section documents the design process for developing a sustainable building system. The design is based on a minimal surface structure to reduce materiality and to optimise strength and its manufacturing process exploits emergent and existing technologies for its generation.

The intention of this project is to research the potential of emergent technologies for developing sustainable composites for the building industry. It is divided into three parts: Part 1 Identifies emergent practices which are being applied to the development of new sustainable building prototypes such as developments using nanotechnologies, the influence of biomimetics, the development of intelligent interactive systems and the use of digital technologies to generate complex cellular structural systems. Part 2 Outlines existing processes involved in selecting and manufacturing prototypes, as many existing processes have been opportunistically applied to emergent practices to generate innovative sustainable prototypes. Part 3 By synthesising the research gathered in the previous parts of this thesis, this section documents the design process for developing a sustainable building system. The design is based on a minimal surface structure to reduce materiality and to optimise strength and its manufacturing process exploits emergent and existing technologies for its generation.

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I have made an investigation in how I can encourage curiosity in textiles with a specific interest in its structures. I have found that repetition is one efficient way to make a separate building element disappear into its own mass and instead be viewed as a surface. I researched how different surfaces are created by experiment with materials and techniques and looked into the big role tactility plays when curiosity in textiles are created but as well realized that a haptic experience can be reached not only with skin but through the eyes. The experiments and elaborations I made took my ideas beyond my starting point and further than I first could imagine. I explored and questioned hierarchies and values of materials by the way I used and combined them. By doing so I realized and discussed the dilemma of being positive to the idea of letting people experience my work through touching and the issue with sustainability, duration and demolishing the patterns while doing so.  Through this paper I aimed to find a definition for what fiber art can be today. I didn´t find one or totally uniform answer but it seems to me that it´s a movement that stretches over diverse material fields and has an underlying power to push boundaries and traditions and break free from classifications.

The diploma thesis is focused on the distribution and role of UV reflectant patterns in beetles (Coleoptera) with focus on the family Scarabaeidae. Through a survey of European museum collections, we discovered over 900 species of UV reflectant beetles, of which 850 species were identified as UV reflectant for the first time. The surface structures responsible for UV reflectant patterns in beetles were studied in detail using a scanning electron microscope. We have identified two ways how the UV reflectant patterns occur. The first way: the light rays interact with the internal structure of the cuticular formations or the cuticle itself; the second way: the light rays interact with the surface layer formed by cuticular secretion. Additionally we carried out experiments with live animals, where we investigated the effect of an individual's age on the intensity of UV reflectant patterns and the effect of UV reflectance on reproductive activity. In a pilot study we were able to show that freshly hatched individuals show a higher level of UV reflectance than older individuals.

Many of the flows in nature are turbulent. To modify turbulent flows, nature serves itself with different types of coatings. Sharks have riblets-like structures on their skin, fishes have slime with polymers and the surface of the lotus flower has superhydrophobic properties. However many times these naturally occurring coatings also serve other purposes. Due to millions of years of adaption, there are anyway many reasons to be inspired by these. The present work is an investigation of nature inspired coatings with the aim of passive flow manipulations. The goal of the investigation has not been to achieve drag reduction, but to achieve a better understanding of the effect of these coatings on turbulent flows. Simulations have been performed in a channel flow configuration, where the boundary condition on one wall has been modified. A macroscopic description has been used to simulate superhydrophobic and porous-like surfaces and a microscopic description has been used to simulate suspended fibers, both rigid and flexible, attached to the channel wall. For the macroscopic description, a pseudo-spectral method was used and for the microscopic description a lattice-Boltzmann method was used. The superhydrophobic modification was implemented using a general slip tensor formulation. In agreement with earlier results, drag reduction was achieved with slip in the streamwise direction and slip in the spanwise direction resulted in drag increase. Non-zero off-diagonal terms in the slip tensor resulted in a slight drag increase, but with rather similar flow behaviour. Transpiration, imitating a porous media, gave rise to drag increase and severely modified the turbulent structures, forming two-dimensional structures elongated in the spanwise direction. For the short fibers, neither rigid nor flexible fibers modified the velocity field to a large extent. The fibers gave rise to recirculation regions and these were seen to be stronger below high-speed streaks. Flexible fibers showed similarities to porous media through a coupling of wallnormal velocity and pressure fluctuations, and this was not seen for the rigid fibers. The fiber deflections were seen to correlate well with the pressure fluctuations. / Många naturligt förekommande flöden är turbulenta. Naturen har också gett upphov till flera typer av ytskikt som kan påverka dessa. Hajars skinn har räfflor, fiskar har slem som innehåller polymerer och lotusblommans yta har superhydrofobiska egenskaper, men ofta har dessa naturliga ytskikt också andra egenskaper. På grund av miljoner år av anpassning så finns det ändå många skäl att studera dessa. Detta arbete är en studie av naturinspirerade ytskikt, där målet har varit passiva flödesmanipulationer. Målet har inte varit att åstadkomma en ytfriktionsminskning, utan att få en bättre förståelse om hur dessa ytskikt påverkar turbulenta flöden. Simuleringar har utförts i en kanalliknande geometri, där en kanalväggs randvillkor har modifierats. En makroskopisk beskrivning har använts för att simulera superhydrofobiska och porösa ytor och en mikroskopisk beskriving har använts för att simulera fibrer, både stela och böjbara, fastsatta på en kanalvägg. För flödet med det makroskopiskt beskrivna randvillkoret har en pseudospektral metod använts och för flödet med det mikroskopiskt beskrivna randvillkoret har en lattice-Boltzmannmetod använts. Den superhydrofobiska ytan implementerades genom en generell tensorformulering. Ett randvillkor med nollskild hastighet i kanalens riktning gav upphov till en ytfriktionsminskning och ett randvillkor med nollskild hastighet vinkelrät mot kanalens riktning gav upphov till en ökad ytfriktion, i överensstämmelse med tidigare resultat. Nollskilda icke-diagonala tensorelement gav upphov till en smärre ökning av ytfriktionen, utan att nämnvärt förändra flödet. De porösa ytorna gav upphov till en ytfriktionsökning och hade stor inverkan på de turbulenta strukturerna. Dessa ytor bildade tvådimensionella struturer vinkelrät mot kanalens riktning. Varken de stela eller de böjbara fibrerna gav upphov till stora ändringar i hastighetsfältet. Däremot uppstor cirkulationszoner och dessa var starkare under stråkstrukturer med hög hastighet. De böjbara fibrerna uppvisade likheter med porösa material genom en interaktion mellan det vertikala hastighetsfältet och de turbulenta tryckfluktuationerna. Denna interaktion uppstod inte för de stela fibrerna. Fibrernas böjning korrelerade också i stor utsträckning till tryckfluktuationerna.

A rapid, mask-less deposition technique for writing metal tracks has been developed. The technique was based on laser-induced chemical vapour deposition. The novelty in the technique was the usage of pulsed ultrafast lasers instead of continuous wave lasers in pyrolytic dissociation of the chemical precursor. The motivation of the study was that (1) ultrafast laser pulses have smaller heat affected zones thus the deposition resolution would be higher, (2) the ultrashort pulses are absorbed in most materials (including those transparent to the continuous wave light at the same wavelength) thus the deposition would be compatible with a large range of materials, and (3) the development of higher frequency repetition rate ultrafast lasers would enable higher deposition rates. A deposition system was set-up for the study to investigate the ultrafast laser deposition of tungsten from tungsten hexacarbonyl chemical vapour precursors. A 405 nm laser diode was used for continuous wave deposition experiments that were optimized to achieve the lowest track resistivity. These results were used for comparison with the ultrafast laser track deposition. The usage of the 405 nm laser diode was itself novel and beneficial due to the low capital and running cost, high wall plug efficiency, high device lifetime, and shallower optical penetration depth in silicon substrates compared to green argon ion lasers which were commonly used by other investigators. The lowest as-deposited track resistivity achieved in the continuous wave laser experiments on silicon dioxide coated silicon was 93±27 µΩ cm (16.6 times bulk tungsten resistivity). This deposition was done with a laser output power of 350 mW, scan speed of 10 µm/s, deposition pressure of 0.5 mBar, substrate temperature of 100 °C and laser spot size of approximately 7 µm. The laser power, scan speed, deposition pressure and substrate temperature were all optimized in this study. By annealing the deposited track with hydrogen at 650 °C for 30 mins, removal of the deposition outside the laser spot was achieved and the overall track resistivity dropped to 66±7 µΩ cm (11.7 times bulk tungsten resistivity). For ultrafast laser deposition of tungsten, spot dwell experiments showed that a thin film of tungsten was first deposited followed by quasi-periodic structures perpendicular to the linear polarization of the laser beam. The wavelength of the periodic structures was approximately half the laser wavelength (λ/2) and was thought to be formed due to interference between the incident laser and scattered surface waves similar to that in laser-induced surface periodic structures. Deposition of the quasi-periodic structures was possible on stainless steel, silicon dioxide coated silicon wafers, borosilicate glass and polyimide films. The thin-films were deposited when the laser was scanned at higher laser speeds such that the number of pulses per spot was lower (η≤11,000) and using a larger focal spot diameter of 33 µm. The lowest track resistivity for the thin-film tracks on silicon dioxide coated silicon wafers was 37±4 µΩ cm (6.7 times bulk tungsten resistivity). This value was achieved without post-deposition annealing and was lower than the annealed track deposited using the continuous wave laser. The ultrafast tungsten thin-film direct write technique was tested for writing metal contacts to single layer graphene on silicon dioxide coated silicon substrates. Without the precursor, the exposure of the graphene to the laser at the deposition parameters damaged the graphene without removing it. This was evidenced by the increase in the Raman D peak of the exposed graphene compared to pristine. The damage threshold was estimated to be 53±7 mJ/cm2 for a scanning speed of 500 µm/s. The deposition threshold of thin-film tungsten on graphene at that speed was lower at 38±8 mJ/cm2. However, no graphene was found when the deposited thin-film tungsten was dissolved in 30 wt% H2O2 that was tested to have no effect on the graphene for the dissolution time of one hour. The graphene likely reacted with the deposited tungsten to form tungsten carbide which was reported to dissolve in H2O2. Tungsten carbide was also found on the tungsten tracks deposited on reduced graphene oxide samples. The contact resistance between tungsten and graphene was measured by both transfer length and four-point probe method with an average value of 4.3±0.4 kΩ µm. This value was higher than reported values using noble metals such as palladium (2.8±0.4 kΩ µm), but lower than reported values using other metals that creates carbides such as nickel (9.3±1.0 kΩ µm). This study opened many potential paths for future work. The main issue to address in the tungsten ultrafast deposition was the deposition outside the laser spot. This prevented uniform deposition in successive tracks close to one another. The ultrafast deposition technique also needs verification using other precursors to understand the precursor requirements for this process. An interesting future study would be a combination with a sulphur source for the direct write of tungsten disulphide, a transition metal dichalcogenide that has a two-dimensional structure similar to graphene. This material has a bandgap and is sought after for applications in high-end electronics, spintronics, optoelectronics, energy harvesting, flexible electronics, DNA sequencing and personalized medicine. Initial tests using sulphur micro-flakes on silicon and stainless-steel substrates exposed to the tungsten precursor and ultrafast laser pulses produced multilayer tungsten disulphide as verified in Raman measurements.

Les structures périodiques de surface induites par laser femtoseconde(fs-LIPSS) attirent l'attention scientifique et technique en raison de la possibilité de produire des nanostructures en dessous de la longueur d'onde optique. Ces éléments sont essentiels pour l'ingénierie de surface et les procédés, notamment en tribologie, mouillabilité, la mécanique, le marquage et la lutte contre la contrefaçon. Selon le régime d'interaction laser, en particulier la fluence du laser, le nombre d'impulsions et le type de matériaux, les impulsions ultracourtes peuvent induire des basses et des hautes fréquences spatiales-LIPSS (LSFL et HSFL), avec l'orientation perpendiculaire (┴E) ou parallèle (║E) à la polarisation du laser. Compte tenu de leur potentiel pour la nano-fabrication, ce travail se concentre sur les mécanismes potentiels de formation des LIPSS, en particulier la formation des HSFL sur les alliages métalliques. Afin d'étudier les indices optiques transitoires de matériaux excités dans la formation fs-LIPSS, nous avons d'abord développé de l’ellipsométrie résolue en temps afin de mesurer les indices optiques dynamiques des matériaux excités. Ainsi, nous avons obtenu un aperçu de la dynamique de la fonction diélectrique intrinsèquement liée à la configuration électronique et au réseau cristallin. Des simulations de premiers principes sont ensuite utilisées pour révéler la façon dont la configuration électronique change au cours de l'excitation, responsable d’indices optiques transitoires. Les effets des indices optiques transitoires sont pris en compte dans les mécanismes de formation de LIPSS. Sur la base d’expériences de formations des fs-LIPSS sur six matériaux différents, incluant du tungstène métallique, du silicium semiconducteur, de la silice fondue diélectrique, un superalliage monocristallin CMSX-4, un alliage amorphe de Zr-BMG et son alliage cristallin correspondant Zr-CA, nous étudions les mécanismes de formation des LIPSS dans le domaine électromagnétique par des simulations de différences finies dans le domaine temporel (FDTD), liées à la distribution d'énergie électromagnétique suivie par la dynamique de l'excitation optique et par l'évolution de la topologie avec le nombre d’impulsions et les matériaux. Nous nous concentrons sur l'origine électromagnétique de la formation des LIPSS et révélons un facteur principal potentiel de leur formation. Elle peut être expliquée par la modulation de l'énergie déposée sur la surface par des effets électromagnétiques. La modulation de l'énergie provient principalement de l'interférence entre le laser incident et les ondes de surface diffusées (pour LSFL ( ┴ E)), complétée par l'interférence entre les ondes de surface diffusées (pour HSFL (┴E)). Spécialement, pour HSFL (║E) sur Zr-CA, nous avons proposé que les scénarios de formation reposent sur des processus individuels d’exaltation anisotrope du champ. La topologie de surface, évoluant avec le nombre d'impulsions laser, induit une modulation d'énergie déposée sur la surface définie et amplifiée par la rétroaction / Femtosecond laser-induced periodic surface structures (fs-LIPSS) attract the scientific and technical attention due to the ability to produce nanostructures below the optical wavelength. These are essential for surface engineering and treatment, notably in tribology, wettability, mechanics, marking and counterfeiting. Depending on the regime of laser interaction, particularly on the laser fluence, pulse number and material type, ultrashort pulses can induce the low- and high-spatial-frequency-LIPPS (LSFL and HSFL), with the orientation perpendicular (┴E) or parallel (║E) to the laser polarization. Considering their potential in the nano-manufacturing, this work focuses on potential mechanisms for LIPSS formation, especially HSFL formation on the metallic alloys. In order to investigate the transient optical indices of excited materials in fs-LIPSS formation, we first developed time-resolved ellipsometry to measure dynamic optical indices of excited materials. Thus we gain insights in the dynamics of the dielectric function where this is intrinsically related to the electronic configuration and lattice structure. First principle simulations are then used to reveal how the electronic configuration changes during the excitation, responsible for the transient optical indices. The effects of transient optical indices are considered in the LIPSS formation mechanisms. Based on the experiments of fs-LIPSS formations on six different materials, involving metal tungsten, semiconductor silicon, dielectric fused silica, single-crystal superalloy CMSX-4, amorphous alloy Zr-BMG and its corresponding crystal alloy Zr-CA, we investigate the LIPSS formation mechanisms in the electromagnetic domain by finite-difference time-domain (FDTD) simulations, related to the electromagnetic energy distribution followed by the dynamics of optical excitation, evolving topologies with pulse number and materials.We focus on the electromagnetic origin of LIPSS formation and reveal a potential primary factor for LIPSS formation. LIPSS formation can be explained by deposited energy modulation on surface via electromagnetic effects. The energy modulation mainly comes from the interference between incident laser and scattered surface wave (for LSFL(┴E)), being complemented by the interference between scattered surface waves (for HSFL(┴E)). Specially, for HSFL (║E) on Zr-CA, we proposed that the formation scenarios rely on individual anisotropic field-enhancement processes. The evolving surface topology with laser pulse number leads to a feedback-driven energy modulation deposited on surface

This thesis reports on the controlled formation of surface rippling structures induced by tip scanning processes on compliant and brittle materials. Periodic surface structures were generated on polymeric and vitreous materials and with different length scales. Two aspects were focused on: the controlling of orientation and periodicity of the resulting structures via proper tuning the scan conditions and the physical mechanisms ruling the early stages of plowing wear causing the rippling effect. Specifically the influence of the scanned area geometric shape on the orientation of the rippling structure was investigated on a polystyrene surface. Nanoripples were induced by scanning the surface with a silicon tip using atomic force microscopy and dedicated scripts. Inside a structured area two ripple orientations can be observed: near boundaries the ripple orientation is determined by boundary orientation and regions away from the boundaries the ripples are aligned in a steady orientation. This steady orientation can be tuned by the distance between the scan lines. In the boundary regions the orientation of the ripples is different from steady orientation. The orientation of the boundaries clearly affected the orientation of the ripples and the tendency of the ripples to align in a steady angle defined by the scan parameters could be significantly modified. Geometric shapes like squares, circles, stars, pentagons and hearts allowed to distinguish the influence of curved and straight boundaries. Straight boundaries with different orientations allowed a detailed analysis of the influence of the angle on the rippling process. Straight boundaries inclined in the direction of the steady state angle of ripple orientation previously defined generate a uniform ripple pattern covering the entire scan area. The aspect of wear originating from the rippled surface was also investigated on similar polystyrene surfaces. As a result of repetitive scan passes spherical particles with diameters up to 250 nm were nucleated and detached from the surface. The particles originate from the crests of the ripples formed in the first scan pass. As proven by the lateral force signal the detachment occurs smoothly without a static friction peak suggesting a crazing mechanism induced by the scanning tip. Once detached from the surface the particles are displaced and piled up along the edges of scanned area. The formation of periodic surface structures was also investigated on a brittle silica glass. By a combination of scratch tests performed with a diamond microtip mounted in a nanoindenter and imaging with atomic force microscopy the existence of a periodic herringbone pattern inside scratch grooves on silica glass was proven. The rippled pattern was induced in the scratch process when the indenter was pulled laterally along the surface resulting in a microscopic scratch groove. The load was varied up to 30 nN and the scan velocity up to 500 µm/s. The resulting periodicity of the structures was found to increase linearly with increasing scratch velocity. The repetition distance was in the range of sub-µm and the corrugation in the range of a few hundred nm, which was well below indentation depth. In both cases, the surface rippling on a polymeric surfaces and the formation of a periodic pattern inside microscratches on a glass surface, the results were found to be consistent with minimalistic theoretical models for stick-slip.:Contents i Abstract iii Zusammenfassung v 1. Introduction 1 1.1. Periodic surface structures – relevance and formation 1 1.2. Surface rippling created by scanning probe lithography 2 1.3. Wear and nanoparticle release 4 1.4. Aim and outline 4 2. Experimental methods and fundamental concepts 6 2.1. Nanolithography 6 2.2. Atomic force microscopy 7 2.3. Nanoindentation and -scratching 10 2.4. Wear 11 2.5. Stick-slip motion 12 2.6. Spin coating 14 3. Surface rippling on polystyrene 15 3.1. Background and motivation 15 3.2. Methods 20 3.2.1. Sample preparation 20 3.2.2. Scanning probe lithography process 20 3.2.3. Imaging of structures and nanoparticles 21 3.3. Effect of boundaries on the orientation of surface rippling 22 3.4. Particle release as a result of surface rippling 31 4. Periodic structures inside scratches on silica glass 37 4.1. Background and motivation 37 4.2. Methods 38 4.2.1. Sample preparation 39 4.2.2. Scratch tests 39 4.2.3. AFM imaging and analysis 39 4.3. Surface rippling induces by scraping with a sharp indenter 40 5. Conclusion and outlook 49 A. Appendix surface rippling on polymers I B. Appendix surface rippling on glass IV Acknowledgements VII References IX

Surfaces equipped with periodic patterns with feature sizes in the micrometer, submicrometer and nanometer range present outstanding surface properties. Many of these surfaces can be found on different plants and animals. However, there are few methods capable to produce such patterns in a one-step process on relevant technological materials. Direct laser interference patterning (DLIP) provides both high resolution as well as high throughput. Recently, fabrication rates up to 1 m²·min-1 could be achieved. However, resolution was limited to a few micrometers due to typical thermal effects that arise when nanosecond pulsed laser systems are used. Therefore, this study introduces an alternative to ns-DLIP for the fabrication of multi-scaled micrometer and submicrometer structures on nickel surfaces using picosecond pulses (10 ps at a wavelength of 1064 nm). Due to the nature of the interaction process of the metallic surfaces with the ultrashort laser pulses, it was not only possible to directly transfer the shape of the interference pattern intensity distribution to the material (with spatial periods ranging from 1.5 μm to 5.7 μm), but also to selectively obtain laser induce periodic surface structures with feature sizes in the submicrometer and nanometer range. Finally, the structured nickel sleeves are utilized in a roll-to-roll hot embossing unit for structuring of polymer foils. Processing speeds up to 25 m·min-1 are reported.