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The broader technical objective of this work is to develop a strategy for using the biopolymer lignin in a wide variety of surfactant applications through polymer grafting. These applications include emulsion stabilizers, dispersants and foaming agents. The scientific objective of the research performed within this thesis is to understand the effect of molecular architecture and polymer grafting on the interfacial activity at the air-liquid, liquid-liquid and solid-liquid interface. Research has focused on designing of these lignopolymers with controlled architecture using polyethylene glycol, poly(acrylic acid) and polyacrylamide grafts. The interfacial activity for all polymer grafts has been tested at all three interfaces using a broad range of techniques specific to the interface. Results have shown that the hydrophobicity of the lignin core is responsible for enhanced interfacial activity at the air-liquid and liquid-liquid interface. Conversely, improved hydrophilicity and “electrosteric” interactions are required for higher interfacial activity of the lignin at the liquid-solid interface. The high interfacial activity of the polymer-grafted lignin observed in the air-liquid and liquid-liquid interfaces not only resulted in viscosity reduction but also strength enhancement at the liquid-solid interface. The broader implication of this study is to be able to predict what chemical functionalities need to be adjusted to get the desired viscosity reduction.

The issue of skin friction related injuries has been one of the problems challenging the artificial sports turf industry. It has been identified by users as a major factor impeding acceptance of artificial turf at the professional level. However, information explaining the mechanisms for skin-turf abrasion is limited and little progress has been made, it appears, to derive an appropriate testing method for product approval or in evidence of improvement of the skin-friendliness of these products in sport surface surfaces. This research project focused on exploring the potential for improving the skin-friendliness of artificial turfs through a multi-faceted approach: identifying the contribution of the abrasive-components in modern artificial turf surfaces through mechanical testing; while critically evaluating currently available skin friction standards , evaluating strategies for polymer material modifications to reduce the skin-surface friction; and the designing of an appropriate bench-top set-up for the lab-based assessment of material skin-friendliness. The lack of understanding of skin-turf interaction was addressed by identifying the turf-component that has the greatest influence on the skin-turf friction with the mechanical device used in the current industry standard. The skin -turf frictional profiles of a series of third generation (3G) turf surfaces were examined, in combination with independent measurements of the silicone skin surface roughness pre- and post-friction testing. Results indicated that turf carpets without any infill material exhibited the highest frictional values while surfaces completely filled with either sand or rubber displayed similarly low frictional values, independent of infill type. Morphological measurements also showed the largest decrease in surface roughness for skin samples tested on carpet-only surfaces, indicating a smoothening effect via abrasion. This abrading effect is alleviated with the addition of infill to the surface, with fully-filled surfaces having the least damage to the skin s. This unprecedented study suggests that the carpet may have the largest influence on the overall frictional behaviour of an artificial turf surface narrowing down the turf component to be targeted when applying product improvements to address skin-friendly properties. The strategy of material surface modification was then employed, to study the effect of polyzwitterionic brushes on improving the skin-friendliness of the identified polypropylene substrate. To address the intended application for artificial turfs, a bench-top test was developed to investigate the frictional properties of the hydrated samples outside of commonly used aqueous environments, where an excess of lubricating water molecules is absent. Photo-grafted poly(sulfobetaine methacrylate) (pSBMA) brushes of various irradiation durations were prepared and the improvement in frictional properties was studied. Frictional measurements using silicone skin tips, under both dry and hydrated surface conditions, showed that the applied modification was capable of forming a stable lubrication layer in the absence of excess water, significantly reducing the coefficient of friction by up to 78.8 %. The pSBMA brushes also provided the additional advantage of antifouling exhibiting resistance towards pathogenic Staphylococcus aureus with almost zero surface colonization for well-grafted samples. The low skin -sample friction under ambient conditions and desirable fouling-resistance highlights the potential of pSBMA brushes as a modification strategy for achieving skin-friendly surfaces targeted at reducing the risk of skin abrasions. The tribological implications of counter-surface selection were investigated. Frictional assessments of the pSBMA-modified samples were carried out using standard steel tribo-tips, in addition to the skin tips used. Measurements with the skin tips showed that the hydrated pSBMA brushes were successful in reducing initial skin -sample friction though the effect diminishes with extended testing, attributed to the drying of the interfacial water. The standard steel tribo-tips were unable to reciprocate these results, returning consistently low frictional values regardless of extent of surface modification or hydration. These observations draw attention to the importance of counter-surface selection in frictional assessments, highlighting how appropriate test materials can identify characteristic surface properties while providing an interaction that simulates that of the intended application. The simple experimental set-up used may potentially be enhanced as an intermediate product qualification method in the manufacturing of skin-friendly artificial turf yarns.

The objective of this thesis is to incorporate cellulose nanocrystals (CNCs) into polymer latexes prepared using various emulsion polymerization methods. CNCs are a promising new class of renewable materials with unique properties including nanoscale dimensions, a high aspect ratio, low density, and high strength. They show significant promise to enhance the properties of existing materials, but challenges often arise due to incompatibility and processing difficulties. This work investigates novel surface modification routes to improve the compatibility of CNCs with emulsion polymerization components, and aims to control the location and function of CNCs in latex systems in order to modify latex properties. Three approaches to incorporate CNCs into polymer latexes are presented: (1) exploiting CNC-surfactant interactions in order to promote CNCs as Pickering stabilizers or as “passive” additives in the water phase, (2) enhancing the surface activity of CNCs by adsorbing the surface active biopolymer methyl cellulose (MC) to act as Pickering co-stabilizers, or (3) hydrophobic modification of CNCs through polymer grafting in order to provide improved compatibility between CNCs and the monomer/polymer phase to incorporate CNCs into the latex core. First, the interactions between CNCs and surfactants were studied in suspension and at surfaces and the CNC-surfactant combinations were used to stabilize miniemulsion polymerization of methyl methacrylate (MMA), a model system used in this work. Oppositely charged CNCs and surfactants showed improved stability as Pickering stabilizers and the ability to co-stabilize the monomer/polymer-water interface. When like-charged CNCs and surfactants were used, the poly(methyl methacrylate) (PMMA) polymer particles were stabilized by surfactant only, while the CNCs remained in the water phase. Next, in order to avoid the use of surfactants, CNCs were coated with MC to provide improved surface activity. MC-coated CNCs were effectively used as Pickering stabilizers in the microsuspension polymerization of MMA, where a double morphology of PMMA particles was observed, and the morphology could be tuned based on the ratio of CNC to MC used. Finally, CNCs were modified with hydrophobic polymer via two different “grafting from” methods: free radical polymerization and atom transfer radical polymerization (ATRP). Free radical polymer grafting from CNCs resulted in polymer-grafted CNCs but the method lacked control over polymer graft length and graft density. To overcome this, CNCs were modified via surface initiated ATRP where considerably higher amounts of polymer were grafted from the CNCs in short reaction times and with simple purification steps. Furthermore, polymer-grafted CNCs were added to the monomer phase of the miniemulsion polymerization of MMA and latexes with CNCs inside the hydrophobic polymer particle core were prepared. Given the difficulties in characterizing polymer grafted CNCs, a novel solution state NMR method was used, whereby the modified CNCs were dissolved in ionic liquids and the polymer grafts were cleaved and collected to determine graft length and graft density. Overall, this work provides three approaches for the preparation of nanocomposite latexes with CNCs using PMMA as a model system. The results presented here may expand the use of CNCs in latex products such as adhesives, paints, coatings, and cosmetics. / Thesis / Doctor of Philosophy (PhD) / This research aims to prepare polymer latexes with tailorable properties using renewably-sourced particles and nanotechnology. Latexes are polymer particles dispersed in water, typically on the order of a few hundred to thousand nanometers (where a “nanometer” is one billionth of a meter), and are used in products such as adhesives, paints, and coatings. The field of nanotechnology takes advantage of nanomaterials where unique properties stem from the small size and high surface-area-to-volume ratio. In this work, we use cellulose, the most abundant natural polymer on earth, in the form of cellulose nanocrystals (CNCs). These nanoparticles are extracted from pulp, cotton, and other natural resources to yield nanometer-sized rigid rod-like particles. CNCs have recently gained attention in research and the media because of their new industrial production and “safe nanomaterial” designation in Canada. In this work, CNCs were chemically modified by the attachment of new molecules or by coating them with polymers and were subsequently added during the synthesis of the polymer latex. Incorporating CNCs imparted new properties and the ability to control latex size, shape, and surface topography. CNCs are also expected to improve the overall mechanical strength of the latex, and may enhance the stickiness of adhesive latexes in particular, leading to products that are more environmentally friendly and that show improved performance.

We develop, characterize, and apply novel solvent systems for enhanced separations. The field of separations has long been explored by chemical engineers. One way to optimize separations is through solvent manipulation. Through molecular design, smart solvents can be created which accomplish this task. Smart solvents undergo step or gradual changes in properties when activated by a stimulus. These property changes enable unique chemistry and separations. This thesis explores the application of two different types of smart solvents: switchable and tunable solvents. First we show that a neutral liquid can react with carbon dioxide and be switched into an ionic liquid which can then be thermally reversed back to its molecular form. Each form that the solvent takes has unique properties that can be structurally tuned to span a large range. We also look at a tunable solvent system based on polyethylene glycol/dioxane that is initially homogeneous, but induced to a heterogeneous system through carbon dioxide pressurization. Finally, we look at the advantage of using carbon dioxide as a co-solvent that is easily removed post-reaction for the grafting of silanes onto polyolefin backbones.

Dans cette thèse, la fonctionnalisation de surface de nanocristaux de cellulose (NCC) par estérification et polymérisation ATRP a été envisagée, dans le but de développer de nouveaux matériaux avancés. Une méthode pratique permettant de caractériser les polymères greffés en surface des NCC a d’abords été développée, à partir des analyses DLS, DSC et TGA. L’efficacité des méthodes SI-ATRP et SI-ARGET ATRP pour initier le greffage de polystyrène (PS) ou poly(4-vinylpyridine) (P4VP) à la surface des NCC a ensuite été comparée. Les nano-hybrides P4VP-g-NCC pH-responsifs, ont alors été utilisés pour stabiliser des nanoparticules d’or (AuNPs), dans le but de produire des catalyseurs recyclables. L’activité catalytique des matériaux Au@P4VP-g-CNC obtenus – testée avec la réduction du 4-nitrophenol – a été améliorée de manière significative par rapport aux AuNPs seuls. Des polymères UV-responsifs de poly(cinnamoyloxy ethyl methacrylate) (PCEM) ont également été greffés à la surface des NCC, pour produire des particules UV-absorbantes. Les nano-hybrides PCEM-g-CNC obtenus se sont avérés efficaces comme stabilisants UV/thermiques et agents de renforts dans les films PVC. Finalement, une méthode facile pour préparer des colloidosomes à partir d’émulsions de Pickering inverses stabilisées par des NCC modifiés par des groupes cinnamates a été proposée. Des colloidosomes aux parois robustes et permettant un relargage lent de molécules encapsulées comme la rhodamine B ou l’acide désoxyribonucléique fluorescent ont alors été obtenus. / In this thesis, the surface functionalization of cellulose nanocrystals (CNC) by esterification and ATRP reactions was envisaged, with the objective to develop novel advanced materials. A convenient method to characterize the polymers grafted on CNC by Si-ATRP has been first developed, based on DLS, DSC and TGA analyses. The efficiency of the SI-ATRP and SI-ARGET ATRP methods to initiate the grating of polystyrene (PS) or poly(4-vinylpyridine) (P4VP) at the CNC surface were then compared. The pH-responsive P4VP-g-CNC nano-hybrids were subsequently utilized to stabilize gold nanoparticles (AuNPs), in view of producing recyclable catalysts. The catalytic activity of the Au@P4VP-g-CNC material – tested with the reduction of 4-nitrophenol – was significantly improved compared with single AuNPs. UV-responsive poly(cinnamoyloxy ethyl methacrylate) (PCEM) polymers were also grafted on CNC, to produce particles with UV absorbing properties. The PCEM-g-CNC nano-hybrids obtained turned out to be efficient UV/thermal stabilizers and reinforcing agents in PVC films. Finally, a facile method to prepare colloidosomes from w/o inverse Pickering emulsions stabilized by cinnamate-modified CNC was proposed. Colloidosomes with robust shells and allowing the slow release of encapsulated molecules such as rhodamine B or fluorescent deoxyribonucleic acid were then obtained.

Ces travaux de recherche s’inscrivent dans le cadre du développement de nouvelles surfaces biocompatibles capables de contrôler l’adhésion d’agents pathogènes responsables de maladies neurodégénératives telles que les maladies de Creutzfeld Jacob, Alzheimer, Parkinson et Lewis. Deux axes de recherche ont été privilégiés. Notre approche se focalise en amont des dosages sur l’amélioration des procédures de stockage des prélèvements biologiques réalisés dans des tubes de type Eppendorf. Ces tubes en polypropylène induisent une perte du matériel génétique de plus de 70% accentuant la faible concentration en agent pathogène pour la détection immunoenzymatique. Dans le but de réduire les phénomènes indésirables d’adhésion des agents pathogènes à la surface des supports de stockage, deux voies de traitement ont été envisagées dans ce travail de thèse. La première consiste à modifier la surface du tube Eppendorf en une étape par décharge plasma fluoré, la seconde à créer de nouvelles surfaces hydrophiles en deux étapes couplant la technique des plasmas froids au greffage de polymères, les agents pathogènes pouvant être hydrophiles ou hydrophobes. Avec cette dernière technique, une voie originale a été abordée de part l’utilisation de solutions de greffage complexes composées à la fois de polymères et de molécules tensioactives. Les surfaces ainsi obtenues présentent une nano-structuration. Toutes les étapes de modification de la surface interne des tubes de stockage ont été caractérisées. Ces surfaces sont alors décrites selon leur caractère hydrophile ou hydrophobe grâce à la détermination des énergies de surface polaire et apolaire, selon leur charge de surface obtenue par mesure du potentiel d’écoulement, selon leur composition chimique déterminée par spectroscopie à photoélectrons X (XPS) et enfin selon leur topographie et leur rugosité relevées par microscopie à force atomique (AFM). Les interactions entre les groupements fonctionnels ainsi obtenus à la surface des tubes de stockage après les divers traitements et les protéines antigéniques considérées ont été interprétées en se référant aux différents modèles de l’adhésion pour des gammes de pH proches des protocoles biologiques usuels. Afin de s’assurer que ces nouvelles surfaces permettent bien une diminution de l’adhésion des agents infectieux sur la paroi interne des tubes de polypropylène, des analyses immunoenzymatiques ont été réalisées au sein des centres hospitaliers participant au projet STREP NEUROSCREEN n° LSHB-CT 2006-03 7719 (CRPP de Liège et CHU de Lyon). Ces analyses ont permis de montrer que la modification des surfaces entraîne une diminution de l’absorption des agents pathogènes jusqu'à 100% permettant ainsi une meilleure détection. / The research work presented in this thesis considers the development of newµbiocompatible surfaces that are able to control the adhesion of specific proteins responsible for the development of neurodegenerative diseases such as Creutzfeldt–Jakob, Alzheimer, Parkinson and Lewis body disease. Our approach was focused on problems prior to the detection step, which were never considered before, particularly on the improvement of Eppendorf tubes that are used for the storage of body fluids like cerebrospinal fluid and blood. Namely these tubes made of polypropylene induce the depletion of biological material, in some cases even over 70%, resulting in a low concentration of these proteins for the further immunoenzymatic detection. With the purpose to reduce the adhesion of specific proteins on the surface of supports, two courses of treatments were anticipated. The first one consists of surface modification by highly reactive fluorine plasma treatment and the second one incorporates development of new hydrophilic surfaces by coupling two techniques, plasma activation and subsequent grafting of polymer materials. With the latter approach, an original way of surface modification has been attained by using complex solutions of polymers and surfactants that permits controlled configuration of nanostructured surfaces. All steps of surface modifications were well characterized by different physicochemical methods. The surface hydrophilic/hydrophobic character was determined by measurements of polar and apolar surface energy, surface charge by magnitude of zeta potential, surface chemistry was evaluated by x-ray photoelectron spectroscopy (XPS), while the surface roughness and topography were monitored by atomic force microscopy (AFM). The interactions between functional groups of treated supports and proteins were interpreted referring to different models of adhesion established for a range of pH values close to the classical biological protocols. Finally, in order to validate that the new surfaces are able to prevent or decrease the adhesion of neurodegenerative agents on the surfaces of Eppendorf tubes, the immunoenzymatic analyses were carried out in hospital centres of partners that were participating to the project STREP NEUROSREEN n° LSHB-CT-2006-03 7719 (Centre de Recherche sur les Protéines Prion; Liege (ULG), Hospices Civils de Lyon (CHUL) and Lancaster University (L-UNI)). These analyses showed that the treatments led to a decrease of antigen adsorption up to 100%, enabling (allowing) better detection of pathogenic agents.

This thesis investigates the effect of reaction media on the efficiency of grafting hydrophobic polymers from cellulose nanocrystals (CNCs) via surface-initiated atom transfer radical polymerization (SI-ATRP), with the goal of producing highly-modified CNCs for incorporation into latex-based pressure sensitive adhesives (PSAs). A latex is a dispersion of polymer particles in water made by emulsion polymerization; latexes are commonly used in paints, coatings, elastomers, inks/toners, household products, cosmetics, and adhesives. However, latex-based PSAs often underperform compared to their organic solvent-polymerized counterparts due to a lack of cohesive strength in the cast latex films. The environmental benefit of using latex-based PSAs synthesized in water is significant, but the development of strategies to improve their performance are required. CNCs are hydrophilic rod-shaped nanoparticles with high mechanical strength. Adding CNCs to latex-based PSAs has been shown to improve both adhesive (i.e., tack and peel strength) and cohesive (i.e., shear strength) properties and offers a degree of sustainability because CNCs are derived from natural cellulose sources such as wood pulp. However, their hydrophilicity, particularly relative to the hydrophobic polymers used in PSAs, has constrained CNCs to the continuous (i.e., water) phase of the latex. To improve CNC compatibility with the dispersed (i.e., polymer) phase and improve their distribution in cast latex films, hydrophobic polymers can be grafted from CNCs. However, CNCs with a high polymer graft density are required to ensure their compatibility with monomers/polymers during latex synthesis. To begin, grafting poly(butyl acrylate) (PBA) from CNCs using SI-ATRP in polar dimethylformamide (DMF) versus non-polar toluene was directly compared. The enhanced colloidal stability of initiator-modified CNCs in DMF led to improved accessibility to surface initiator groups during polymer grafting. As such, PBA-grafted CNCs produced in DMF had up to 30 times more grafted polymer chains than PBA-grafted CNCs produced in toluene. The PBA-grafted CNCs produced in DMF showed high contact angles when cast in a film and formed stable suspensions in toluene. This work highlights that optimizing CNC colloidal stability in a given solvent prior to polymer grafting is a more crucial consideration than solvent–polymer compatibility in the context of obtaining high graft densities and thus hydrophobic CNCs via SI-ATRP. The improved polymer grafting method in DMF was then used to produce PBA and poly(methyl methacrylate) (PMMA)-grafted CNCs at two polymer chain lengths. Polymer grafted CNCs were incorporated in situ during a seeded semi-batch emulsion polymerization to produce PBA latex nanocomposite PSAs. Viscosity measurements revealed significant differences between latexes prepared with CNCs versus polymer-grafted CNCs, with the lower viscosities of the latter suggesting their incorporation inside the polymer particles. When CNCs with short polymer grafts were introduced into PSAs at 1 wt. % loading, they exhibited comparable tack and improved peel strength compared to unmodified CNCs (and all properties improved relative to the base latex without any CNCs). This is attributed to their improved distribution throughout the PSA, the enhanced wettability of the substrate with the CNC containing latex, and the increased polymer chain mobility achieved based on the low molecular weight of the grafts. CNCs with long polymer grafts aggregated in the latex and did not improve PSA properties. PMMA-grafted CNCs slightly outperformed PBA-grafted CNCs likely due to the higher glass transition temperature of PMMA. These results provide insight into future optimization of more sustainable latex-based PSA formulations as well as new commercial CNC-latex products, where the presence of low molecular weight grafts on CNC surfaces could improve polymer mobility and tack and peel strength. / Thesis / Master of Applied Science (MASc) / When the adhesives used in tapes, labels or sticky notes are produced using water-based reactions, they normally underperform compared to conventional adhesives produced using toxic solvents. To improve such water-based adhesives, adding nanocellulose (tiny particles derived from wood pulp) during synthesis has been shown to be an asset. Nanocellulose can be chemically modified to improve its compatibility with adhesive ingredients, and thus change the role of nanocellulose during adhesive manufacturing. In this thesis, modified nanocelluloses were added to water-based adhesives to evaluate their effect on performance (i.e., strength and stickiness). It was found that the reaction conditions during nanocellulose modification were crucial for obtaining highly modified particles that are compatible with adhesive ingredients. This work aims to provide insight for future production of less environmentally taxing adhesives made in water and expand the use of nanocellulose in new commercial products.

The research presented in this dissertation focuses on the design and synthesis of novel hybrid conjugated polymer materials using two different approaches: 1) inorganic/organic hybrid semiconductors through the incorporation of carboranes into the polymer structure and 2) the modification of surfaces with conjugated polymers via grafting approaches. Hybrid conjugated polymeric materials, which are materials or systems in which conjugated polymers are chemically integrated with non-traditional structures or surfaces, have the potential to harness useful properties from both components of the material to help overcome hurdles in their practical realization in polymer-based devices. This work is centered around the synthetic challenges of creating new hybrid conjugated systems and their potential for advancing the field of polymer-based electronics through both greater understanding of the behavior of hybrid systems, and access to improved performance and new applications. Chapter 1 highlights the potential applications and advantages for these hybrid systems, and provides some historical perspective, along with relevant background materials, to illustrate the rationale behind this work. >Chapter 2 explores the synthesis of poly(fluorene)s with pendant carborane cages. The Ni(0) dehalogenative polymerization of a dibromofluorene with pendant carborane cages tethered to the bridging 9-position produced hybrid polymers produced polymers which combined the useful emissive characteristics of poly(fluorene) with the thermal and chemical stability of carborane cages. The materials were found to display increased glass transition temperatures and showed improved emission color stability after annealing at high temperatures relative to the non-hybrid polymer. The design and synthesis of a poly(fluorene)-based hybrid material with carborane cages in the backbone, rather than as pendant groups, begins in chapter 3. Poly(fluorene) with p-carborane in the backbone is synthesized and characterized, and the material is found to be a high MW, soluble blue emitter which shows a higher glass transition temperature and greater stability than a non-hybrid polymer. UV absorbance and fluorescence spectroscopy indicated some electronic interaction between the conjugated polymer and the cages, but they did not appear to be fully conjugated in the traditional sense. Chapter 4 describes the design, synthesis, and characterization of poly(fluorene) with o-carborane in the backbone. Profound changes in the behavior of the polymer, from its polymerization behavior to its emission characteristics, were observed and their origins are discussed. Experiments to explore the nature of the cage/polymer interactions were performed and possible applications which take advantage of the unique nature of the o-carborane hybrid polymer are explored and discussed. Hybrid conjugated polymer materials via grafting approaches to surfaces and surface modification are discussed starting in chapter 5. The synthesis of a dibromofluorene-based silane coupling agent for the surface functionalization of oxide surfaces is presented, and the surface directed Ni(0) dehalogenative polymerization of poly(dihexylfluorene) is explored. Chapter 6 focuses on the exploration of conjugated polymer/cellulose hybrid materials. Surface medication of cellulose materials with monomer-like anchor points is discussed. Grafting of the modified cellulose with conjugated polymers was explored and the grafting of three different repeat structures based on fluorene-, fluorenevinylene-, and fluoreneethynylene motifs were optimized to provide a general route to cellulose/conjugated polymer hybrid materials. Characterization and possible applications of such hybrid materials are discussed. Finally, chapter 7 is devoted to the simultaneous surface patterning and functionalization of poly(2-hydroxyethylmethacrylate) thin films using a silane infusion-based wrinkling technique. While not a conjugated polymer system, the spontaneous patterning and functionalization methods explored in this chapter produce hybrid organic/inorganic polymer thin films which have applications that range from optics, to adhesion, to polymer-based electronics, and the research compliments the other chapters. The spontaneous generation of complex patterns, of a small scale approaching 100nm feature size, over a large area with simultaneous control over surface chemistry is explored. Examples of complex, hierarchically patterned films which integrate lithographic processes such as nanoimprint lithography and electron beam lithography with spontaneous patterning via wrinkling are presented.

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