Chitosan is known for its hemostatic and antimicrobial properties and might be useful for temporary coating of removable dentures or intraoral splints to control bleeding after oral surgery or as a supportive treatment in denture stomatitis. This study investigated a new method to adhere chitosan to polymethyl methacrylate (PMMA) and polyethylene terephthalate (PET). There were 70 cylindrical specimens made from PMMA and 70 from PET (13 mm diameter, 6 mm thickness). The materials with ten specimens each were sandblasted at 2.8 or 4.0 bar with aluminum oxide 110 μm or/and aluminum oxide coated with silica. After sandblasting, all specimens were coated with a 2% or 4% acetic chitosan solution with a thickness of 1 mm. Then the specimens were dried for 120 min at 45 °C. The precipitated chitosan was neutralized with 1 mol NaOH. After neutralization, all specimens underwent abrasion tests using the tooth-brushing simulator with soft brushes (load 2N, 2 cycles/s, 32 °C, 3000 and 30,000 cycles). After each run, the specimen surfaces were analyzed for areas of remaining chitosan by digital planimetry under a light microscope. The best chitosan adhesion was found after sandblasting with aluminum oxide coated with silica (U-Test, p < 0.05) in both the PMMA and the PET groups. Hence, with relatively simple technology, a reliable bond of chitosan to PMMA and PET could be achieved.

Chitosan is a cationic natural polymer that is widely used as a topical dressing in wound management. Temporary coatings of removable denture bases with chitosan might be useful as supportive treatment in oral medicine. The aim of this study was to analyze the thickness, uniformity, and adhesive strength of chitosan coatings on simulated denture bases made from polymethyl methacrylate (PMMA). According to a standardized protocol, 20 PMMA cylinders (13 mm diameter, 5 mm in height) as well as 20 cubes (a = 25 mm) with intaglio U-shaped profiles were manufactured to simulate average sized alveolar ridges. Cylinders as well as cubes were divided into four test series with n = 5 each. After sandblasting with silica-modified alumina, one frontal surface of the PMMA cylinders and the intaglio surfaces of the U-shaped profiles was coated with chitosan acetate solution according to the following protocols: one layer of 2% chitosan acetate solution (test series I), one layer of 4% chitosan acetate solution (test series II), two layers of 2% chitosan acetate solution (test series III), and two layers of 4% chitosan acetate solution (test series IV). After drying and neutralization with NaOH, each cube was cut transversely and the coating thickness across the U-shaped profile assessed with a light microscope. Adhesive strength was evaluated by simulated tooth brushing and the loss of chitosan coating was evaluated qualitatively. Statistical analysis used Friedman ANOVA test for dependent samples and Kruskal-Wallis test for independent samples, post-hoc Dunn’s test (p < 0.05), and binomial test (p = 0.05). The mean chitosan coating thicknesses in the depth of the U-profiles were 71 µm (test series I), 77 µm (test series II), 121 µm (test series III), and 517 µm (test series VI). The thickness continuously decreased with rising angulation of the U-profile side walls. In test series I, the chitosan coating thickness significantly dropped above a 30° angulation of the U-profile side walls. In test series II to IV, the chitosan thickness drop was not statistically significant at angulations of 30° and 60°, but was at 90° angulation of the U-profile side walls. Adhesion strength was rated fair to good and did not differ significantly among the four test series. The coating technique described revealed chitosan layers with overall good adhesion strength but differing thicknesses. Coatings with one or two layers of 4% chitosan acetate solution allowed a relatively uniform chitosan thickness and thus might be usable in oral medicine.

In oral sciences, chitosan application is of interest due to its antimicrobial and hemostatic activity. Chitosan coating of dentures and other intraoral devices could be beneficial for treatment of denture stomatitis or in the management of postoperative bleeding. Disinfection of dentures and prosthodontic materials is crucial before their use in patients. This study investigated the influence of chemical disinfectants on chitosan-coated surfaces. A total of 100 specimens were made: 50 of PMMA (polymethyl methacrylate), and 50 of PETG (polyethylene terephthalate glycol-modified) material and coated with 2% chitosan acetate solution. In each material, 5 groups (10 specimens each) were established and disinfected with Printosept-ID (L1), MD 520 (L2), Silosept (L3), or Dentavon (L4), or stored in distilled water (L0, control group). After disinfection, all specimens underwent abrasion tests (30,000 cycles in a tooth-brushing simulator). Areas without chitosan coating were measured by digital planimetry both before and after the disinfection/abrasion procedure and a damage-score was calculated. Regarding chitosan coating, the statistical analysis showed a significant influence of the disinfectants tested and significant differences between disinfectants (p < 0.05). Chitosan coating was most stable on PMMA and PETG after disinfection with MD 520 (L2). Otherwise, active oxygen containing disinfectants (L3, L4) led to the greatest alterations in the chitosan coating.

Dans une thématique de sécurité incendie, la prédiction de la propagation d’une flamme le long d’une paroi verticale solide nécessite la quantification du rayonnement. L’objectif de la thèse est de quantifier et caractériser les suies d’une flamme de PMMA. La flamme stationnaire d’un brûleur gaz sera également étudiée. La méthode optique de LII, une fois calibrée (extinction), permet d’obtenir des champs 2D de la fraction volumique ainsi que le taux de combustion en fonction de la hauteur pour la flamme de PMMA. Ensuite, la morphologie des agrégats de suie est déterminée grâce à des clichés MET et des mesures de la distribution en taille. Les propriétés optiques sont obtenues avec des mesures in-situ et ex-situ (effet de la température) de l’extinction spectrale, couplées avec une mesure de la concentration massique pour remonter à la fonction d’indice. Cette base de données permettra la perspective de calculer le rayonnement des suies et de l’utiliser dans un modèle de propagation. / In the field of fire safety, the propagation prediction of a flame along a solid vertical wall requires radiation quantification. The thesis objective is to quantify and characterize the PMMA flame soot. Gaseous burner steady flame will also be studied. The LII optical method, after calibration (extinction), provides 2D volume fraction fields and the combustion rate in function of the height for the PMMA flame. Then, the soot aggregate morphology is determined by TEM images and size distribution measurements. The optical properties are obtained with in-situ and ex-situ measurements (temperature effect) of the spectral extinction, coupled with a mass concentration measurement to obtain the index function. This database will allow the prospect to calculate the soot radiation and to use it in a propagation model.

Purpose – The aim of the study is to investigate the possibilities for circular economy in acrylicplastic in the lighting industry. To answer the purpose, it was broken down into two researchquestions: [1] What characterizes the handling of acrylic plastic waste by lighting manufacturers? [2] How can lighting manufacturers achieve a more circular handling of acrylic plastic waste? Method – To be able to answer the research questions, a case study was conducted at acompany active in the lighting industry. The data collection consisted of observations,interviews, and document studies. The observations were unmasked and of a direct nature. Theinterviews that were held were both unstructured and semi-structured. The documents wereinvoices and quotations mostly collected from the case company. Furthermore, four differentsolutions were developed with help of the theoretical framework and collected data. The empiricand the theoretical chapters were compared to be able to analyse and answer the researchquestions. Findings – The study shows that a company in the lighting industry throw away plastic lensesas they believe that they have no use for them. The lenses are made of acrylic plastic and arethrown in combustible waste. The waste goes to energy recovery that provides electricity,district heating and district cooling. During the combustion process, carbon dioxide is releasedwhich affects the environment. It is better to let the waste go to energy recovery than landfilling.To achieve a more circular handling of acrylic plastic waste, it is recommended to first andforemost reduce the waste. It is the result of one of the solution proposals "Minimize worksteps" which involves a point effort to take advantage of acrylic plastic instead of throwing itaway. In situations where there is no possibility of reducing, companies should instead try toreuse the acrylic lenses, which is a result of the solution proposal "reuse". In 2024, there willopen a new chemical recycling centre in Sweden that companies should keep track of. Implications – The study has implications for companies in the lighting industry that useacrylic plastic. It is also suitable for companies outside the lighting industry that handle acrylicplastic waste, as the study contributes to increased knowledge about circular economy and howacrylic plastic waste should be handled to benefit the circular economy. The study helps tohighlight potential approaches for environmentally friendly handling of acrylic plastic. A newrecycling centre opens 2024 in Stenungsund, which is the first in Sweden that can chemicallyrecycle acrylic plastic. It is recommended to talk to them early to review costs and opportunitiesthat arise in connection with the opening of the recycling centre. Limitations – The environmental impact of the study is measured in carbon dioxideemissions. No other environmental aspects are considered as carbon dioxide includes the areasthat are relevant, based on the size of the study. Due to the time constraint, the study wasconducted on only one case company, which may lower credibility. More companies should bestudied in order to further generalize and strengthen credibility even more.

Doctor of Philosophy / Department of Chemistry / Takashi Ito / We have investigated the orientation of cylindrical domains in thin films of a polystyrene–poly(methylmethacrylate) diblock copolymer (PS-b-PMMA) on planar substrates having different surface roughnesses and hydrophilicities. The research in this dissertation covers the substrate surface modifications, the enhancement of the diblock copolymer film coating, and the refinement of the treatments leading to nanoporous material. Treatment of the substrate with organic mercaptans forming self-assembled-monolayer (SAM), leading to various hydrophilicities of the surfaces, was inconclusive as far as orienting the PMMA domains in the PS matrix due to thermal instability of some thiols. This directed us to a different approach involving substrate roughness. PS-b-PMMA films of 20~200 nm thick were prepared via spin-coating on silicon, gold or indium tin oxide (ITO) substrates, and annealed in vacuum at 170 °C for 60 hours to induce the formation of cylindrical PMMA domains. Atomic force microscopy (AFM) images indicated the domain orientation at the free surface. In PS-b-PMMA films much thicker than the domain periodicity (L0), the domains were oriented perpendicularly to the free surface regardless of underlying substrates, reflecting the balanced interactions of PS and PMMA blocks at the polymer–vacuum interface. In films having thickness similar to L0, vertically oriented domains were observed on the Au and ITO surfaces that are covered with nanoscale grains, whereas horizontal domains were observed on the smooth Si substrates. In particular, the cylindrical PMMA domains were efficiently perpendicularly aligned when the grain size nearly was equal to L0. The perpendicular domain alignment induced by the substrate roughness was corroborated using cyclic voltammetry (CV) for gold substrates coated with PS-b-PMMA films whose PMMA domains were removed by UV and subsequent acetic acid treatments. The CV data also suggested that the PMMA domains were successfully removed, leaving a nanoporous stable PS matrix on the substrate.

Cancerous solid tumors can migrate and lead to metastatic bone disease. Drugs prescribed to reduce bone resorption from metastasis, such as zoledronic acid and the RANKL-inhibitory antibody Denosumab, cause side effects such as osteonecrosis of the jaw when delivered systemically. This project used two biocompatible materials, acrylic bone cement (PMMA) and poly(lactic-co-glycolic acid) (PLGA), to incorporate and sustain release of anti-resorptive agents. Results showed similar mechanical properties for acrylic bone cements loaded up to 6.6% drug by weight. Results showed sustained zoledronic acid release for 8 weeks from both systems, with PMMA releasing up to 22% of loaded drug and PLGA films releasing over 95%. The antibody release rate was lower, with the majority of antibody still inside the PLGA films after 8 weeks. In vitro bioactivity remained above 50% for zoledronic acid eluted from both materials at early, middle, and late time points. This study sheds light on the behavior of these biocompatible polymers at high drug weight percent loadings compared to previous studies. PLGA demonstrated superior release kinetics but inferior bioactivity of eluted drug. By incorporating anti-resorptive drugs into locally implantable materials, this work could lead to a treatment offering improved quality of life for cancer patients.

La dégradation par fretting-corrosion des prothèses de hanche cimentées est l'une des principales causes de réintervention chirurgicale. L'étude du fretting-corrosion est effectuée entre un acier inoxydable 316L, matériau utilisé pour les tiges fémorales, et un polymère PMMA, matériau modèle du ciment chirurgical, dans différentes solutions, plus ou moins proches du liquide physiologique.L'étude a d'abord été réalisée à potentiel libre (OCP) pour être proche des conditions in vivo. L'influence des chlorures et le rôle de l'albumine, principale protéine du liquide physiologique, sur la dégradation du 316L et de sa couche passive sont ainsi évalués.Pour pouvoir obtenir des informations sur le courant de corrosion, des essais sont effectués à potentiel imposé. Le potentiel choisi est proche de la valeur de potentiel pendant fretting : E = -400 mV(ECS). Ce potentiel permet d'observer la transition entre courant cathodique et courant anodique en fonction de la force ionique. Lors d'un essai de fretting-corrosion, l'albumine joue le rôle d'inhibiteur de corrosion.La dégradation du 316L par fretting-corrosion est une combinaison entre l'usure corrosive, due au milieu physiologique contenant des chlorures, et l'usure mécanique. Il existe un terme de synergie entre usures corrosive et mécanique. L'influence de la force ionique et de l'albumine sur ce terme de synergie est aussi quantifiée.La forme de la trace d'usure en "W", caractéristique du fretting-corrosion, est due à un gradient de pH et à un mécanisme de corrosion proche de la corrosion caverneuse. Une étude à pH global imposé a permis d'estimer les valeurs probables de pH dans et à une courte distance de la zone d'usure.

The third generation of hip resurfacing commenced in the U.K. in the 1990’s with the Birmingham Hip Resurfacing system and is now becoming more commonplace as an attractive alternative for young and active patients due to premature failure in total hip replacement in this patient group. However the Swedish National Hip Arthroplasty Register (2010) suggests that premature failure of resurfacing arthroplasty may be more prevalent than first expected. The aim of this study is to investigate, through Finite Element Analysis, the short, medium and long term performance of Poly Methyl Methacrylate (PMMA) bone cement of the femoral component in hip resurfacing arthroplasty. The study takes a forensic engineering approach, analysing the performance of PMMA bone cement in order to provide understanding, awareness and an insight into lifestyle options. Finite Element Analysis explores and models the effect of resting periods during daily activities, patients’ bone quality and PMMA bone cement Young’s modulus on the PMMA bone cement stresses within the femoral hip resurfacing component. Mechanical tests are used to illustrate the use of the Finite Element Analysis results. Contributing to knowledge, this study verifies the significance of high metal-on-metal friction due to resting periods, developing a dynamic FEA model to quantify the premature fatigue failure of PMMA bone cement, within the femoral component of hip resurfacing arthroplasty. A decrease in bone quality added to the effect of resting periods increase the risk of PMMA fatigue failure and PMMA-metal interface failure due to an increase of PMMA tensile and shear stresses, suggesting that patients with low bone quality should avoid hip resurfacing procedures. The use of low PMMA Young’s modulus could greatly enhance the long term success of hip resurfacing arthroplasty generally and specifically reduce the risk of interface failure and PMMA bone cement failure due to resting periods and patient bone quality. Moreover, this study shows that the consequence of PMMA fatigue failure and PMMA-metal interface failure must be included in the design, patient selection, screening process, post-operative rehabilitation and long term lifestyle attributes. This study suggests that occupational therapists and patients with hip resurfacing arthroplasty should be aware of high metal-on-metal friction situations, which could lead to early failure indicated by this research. The deleterious effect of resting periods indicated by this research could be alleviated by appropriate re-initiation of synovial lubrication by movement prior to full loading. Recommendations for further work include the compilation of a PMMA bone-cement fatigue properties database and further development of the FEA modelling technique for application upon other arthroplasty procedures.

L'objectif de ce travail est l'élaboration de nouveaux matériaux nanocomposites hybrides à propriétés spécifiques (piézoélectricité, optique non-linéaire). Dans un premier temps, des modèles numériques simples portant sur les propriétés mécaniques des nanocomposites sont présentées, ainsi que des simulations de déformation réalisées sur les nanocomposites à nanoparticules piézoélectriques. Les résultats expérimentaux de caractérisation mécanique (par spectrométrie Brillouin) et tribologique de différents nanocomposites sont exposés, y compris de nanocomposites réalisés au sein du laboratoire. L'influence des nanoparticules et de leur fonctionnalisation sur la matrice polymère y est discutée, et en particulier leur incidence sur les volumes libres dans les nanocomposites. Plusieurs procédés de synthèse de nanoparticules aux propriétés piézoélectriques ont parallèlement été étudiées. En particulier, un protocole de synthèse de nanoparticules de LiNbO3 a été mis au point. Ces nanoparticules ont été caractérisées par des techniques structurales, chimiques et d'imagerie. Enfin, ces travaux ont conduit à l'élaboration de films nanocomposites à matrice PVDF-TrFE incorporant des nanoparticules produites en laboratoire ou d'origine commerciale. Les méthodes de polarisation des films sont décrites, et les propriétés piézoélectriques de ces films nanocomposites ont été mesurées. Plus particulièrement, des films nanocomposites PVDF-TrFE/Al2O3 polarisés présentant une bonne réponse piézoélectrique ont été élaborés. / This work aims at the elaboration of new hybrid nanocomposites with specific properties (piezoelectricity, non-linear optic). First, simple numeric modelings on mechanical properties of nanocomposites are presented, as well as simulation of deformation in nanocomposites with piezoelectric nanoparticles. Experimental results on tribological and mechanical (performed by Brillouin Spectroscopy) characterization of different nanocomposites are exposed. The influence of nanoparticles and their fonctionalization on the polymer matrix is discussed, and in particular the incidence on free volume in nanocomposites. Several piezoelectric nanoparticles synthesis processes have been also studied. In particular, a LiNbO3 nanoparticles synthesis protocol has been worked out. These nanoparticles were characterized by structural, chemical and imaging techniques. Finally, these works leads to the elaboration of PVDF-TrFE matrix thin films nanocomposites filled with commercial or produced in laboratory nanoparticles. The methods used to polarize the films are described. The piezoelectric properties of the nanocomposites have been measured. More particularly, PVDF-TrFE/Al2O3 nanocomposites thin films with a good piezoelectric response have been elaborated.