Three-dimensional (3D) printing has an important role for fabrication of degradable scaffoldsfor soft tissue regeneration. Among the 3D printing techniques, photopolymerization-based 3Dprinting is one of fastest growing, offering environmental benefits and high precision of 3Dobjects. In this approach, photocurable macromonomers/monomers are cross-linked layer bylayer in the presence of photoinitiators under visible or UV light to fabricate 3D designedobjects. However, a limited biomedical material selection has prevented it from spreading overclinical application. Furthermore, poly(ε-caprolactone), a common degradable polymer usedfor 3D printing, shows not satisfactory physical properties for soft tissue regeneration. Thedearth of materials with proper properties raises the need for novel degradable materials,which should be not only compatible for photopolymerization-based 3D printing but alsosuitable for soft and gel-like scaffold fabrication. Here, the aim was to design photocurable macromonomers consisting of oligo(ε-caprolactoneran-p-dioxanone), oCLDX, with acrylate chain-end groups. A metal-free synthetic strategy wasdeveloped for the bulk ring-opening of ε-caprolactone (CL) and p-dioxanone (DX) at roomtemperature using diphenyl phosphate (DPP) as organocatalyst and multifunctional initiators. The oligomers had low dispersity (<1.2) and targeted molecular weight around 2000 g mol-1.The random sequence and the control over chain growth of oCLDXs were confirmed byreactivity ratios using 1D and 2D NMR analysis. Kinetics study of co-oligomerizationdemonstrated that within DPP-catalysed reaction, DX possessed higher reactivity than CL andthe ring-opening co-oligomerization followed an activated monomer mechanism (AMM). Thetopology of the co-oligomers could also be varied by using different alcohol initiators. The co-oligomers possessed lower degree of crystallinity than homopolymers of DX or CL and,depending on the composition, they were liquid at room temperature. The lower melting pointand gel-like appearance make them good candidates for photopolymerization-based 3Dprinting. The suitability toward photopolymerization was proven for the ethylene glycol-initiatedco-oligomer containing 30 mol% of DX. The cross-linked gels were soft but brittle and showedgood water uptake capacity. / Tredimensionell (3D)-utskrift har en viktig roll vid tillverkning av nedbrytbara matriser förregenerering av mjukvävnad. Bland 3D-utskriftteknikerna är fotopolymerisationsbaserad 3Dutskriften av de snabbast växande, och erbjuder miljöfördelar och hög precision hos 3Dobjekten.För att tillverka 3D-designade objekt med denna teknik är fotohärdandemakromonomerer/ monomerer tvärbundna lager på lager i närvaro av fotoinitiatorer och synligteller UV-ljus. Emellertid har ett begränsat urval av biomedicinska material hindrat tekniken frånatt spridas till kliniska applikationer. Vidare har poly(ε-kaprolakton), en vanlig nedbrytbarpolymer som används för 3D-utskrift, inte tillfredsställande fysikaliska egenskaper förregenerering av mjukvävnad. Bristen på material med rätt egenskaper ökar behovet av nyanedbrytbara material, som inte bara ska vara kompatibla för fotopolymerisationsbaserad 3Dutskriftutan också lämplig för mjuk och gelliknande matristillverkning.Här var syftet att designa fotohärdande makromonomerer bestående av oligo(ε-kaprolaktonsam-p-dioxanon), oCLDX, med akrylatkedjeändgrupper. En metallfri syntetisk strategiutvecklades för bulkringöppning av ε-kaprolakton (CL) och p-dioxanon (DX) vidrumstemperatur genom att använda difenylfosfat (DPP) som organisk katalysator ochmultifunktionella initiatorer. Oligomererna hade den förutbestämda molekylvikten, omkring2000 g mol-1, och en låg dispersitet (<1,2). Den slumpmässiga sekvensen och kontrollen avkedjans tillväxt, till oCLDX, bekräftades genom reaktivitetsförhållanden med hjälp av 1D och2D NMR-analys. Kinetikstudie av samoligomeriseringen visade att med DPP-katalyseradreaktion hade DX högre reaktivitet än CL och att den ringöppnande samoligomeriseringenföljde en aktiverad monomermekanism (AMM). Topologin hos samoligomererna kunde ocksåvarieras genom att använda olika alkoholinitiatorer. Samoligomererna hade lägre grad av kristallinitet än homopolymerer av DX eller CL ochberoende på kompositionen var de flytande vid rumstemperatur. Den lägre smältpunkten ochgelliknande utseendet gör dem till bra kandidater för fotopolymerisationsbaserad 3D-utskrift. Lämpligheten för fotopolymerisation bevisades för den etylenglykolinitierade samoligomerensom innehöll 30 mol% DX. De tvärbundna gelerna var mjuka men spröda och uppvisade godvattenupptagningskapacitet.

Microalgae are gaining more attention for several reasons such as being potential producers of sustainable fuel, for use as health supplements and in skincare. Simris Alg is a Swedish company that produces Omega 3 supplements from a primary producer of these fatty acids - the algal diatom Phaeodactylum tricornutum, which is a sustainable alternative to Omega 3 derived from fish. Omega 3 fatty acids constitute a small fraction of the total algal biomass, and to increase profitability and utilize all of the biomass, the purpose of this thesis project is to present potential applications for the residual material that is left after oil extraction. A general composition study was made of Simris Alg algal residue material, and results are compared to those found in previous studies of P. tricornutum biomass. An optimization of the fractionation is needed to separate the storage carbohydrate chrysolaminarin and cell wall component glucuronomannan, followed by analysis for confirmation. Also, it would be interesting to separate chitin, if there is any, since despite the presence of chitin synthases, it is unclear whether the diatom actually produces chitin. When gathering information, no actual experimental characterization of carbohydrate active enzymes involved in synthesis of the main carbohydrates investigated were found. Such information would be useful to increase production of the carbohydrate of interest, if valuable applications are found. Potential applications of various cell components, such as carbohydrates, in skincare would be interesting to investigate, as well as optimizing fucoxanthin extraction for use as an additional high value product next to Omega 3.

Diffusion of liquids into and through polymers is an important factor that negatively may influence the durability or lifetime of a polymer structure used in industrial applications. In this work two types of polymers, a liquid crystalline polymer (LCP, Vectra A950) and various thermoset resins as used in fibre reinforced plastics (FRP) process equipment were studied with regard to barrier properties, chemical resistance and long-term performance. LCP are known for their outstanding chemical resistance and barrier properties. FRP used in process equipment may be a cost-efficient solution in chemically aggressive environments where standard carbon or stainless steel cannot be used due to its limited corrosion resistance. Transport properties of typical industrial environments were determined for the LCP and the influence of annealing and orientation was investigated to study whether the barrier properties can be improved. The possibility to use LCP as cost-effective lining for FRP was explored. Special focus was put on the diffusion of water and its effect on long-term transport properties and stability of thermoset resins as the performance of FRP is strongly related to the diffusion of water. The results showed that Vectra A950 was suitable for organic solvent and non-oxidising acid environments. Its transport properties were gravimetrically determined and found to be 10 to 102 times lower than that of a high barrier fluoropolymer of type FEP. The degree of molecular packing increased with annealing time both below and above the melting point. Below the melting point this was – at least – partly due to crystal formation whereas above the melting point other mechanisms were involved. The effects of annealing and orientation on the transport properties in LCP were, however, very small or not significant and probably significantly longer annealing times are required. LCP has potential to be used as lining material for FRP as the use of an LCP-lining substantially reduced the permeability of and the solute sorption in a bisphenol A epoxy-based vinyl ester resin. The bonding strength was improved significantly by a combined abrasive and oxygen plasma treatment. The long-term sorption of water in thermoset resins including bisphenol A epoxy-based vinyl ester, novolac-based vinyl ester, urethane modified vinyl ester and bisphenol A polyester resins was found to increase with exposure time whereas the diffusion coefficient was not significantly affected. It was shown that the presence of water induced relaxation processes that were considered to be the primarily reason for the increase in sorption coefficient in comparison to degradation processes, such as hydrolysis, causing osmotic processes. A general relationship for the estimation of the sorption coefficient at 80ºC in dependence of the water activity and the sorption coefficient at unit activity independent of the resin type was established.

Background: Separation science is heavily reliant on materials to fulfill ever more complicated demands raised by other areas of science, notably the rapidly expanding molecular biosciences and environmental monitoring. The key to successful separations lies in a combination of physical properties and surface chemistry of stationary phases used in liquid chromatographic separation, and this thesis address both aspects of novel separation materials. Methods: The thesis accounts for several approaches taken during the course of my graduate studies, and the main approaches have been i) to test a wild-grown variety of published methods for surface treatment of fused silica capillaries, to ascertain firm attachment of polymeric monoliths to the wall of microcolumns prepared in silica conduits; ii) developing a novel porogen scheme for organic monoliths including polymeric porogens and macromonomers; iii) evaluating a mesoporous styrenic monolith for characterization of telomers intended for use in surface modification schemes and; iv) to critically assess the validity of a common shortcut used for estimating the porosity of monoliths prepared in microconduits; and finally v) employing plasma chemistry for activating and subsequently modifying the surface of rigid, monodisperse particles prepared from divinylbenzene. Results: The efforts accounted for above have resulted in i) better knowledge of the etching and functionalization parameters that determine attachment of organic monoliths prepared by radical polymerization to the surface of silica; ii) polar methacrylic monoliths with a designed macroporosity that approaches the desired "connected rod" macropore morphology; iii) estab¬lishing the usefulness of monoliths prepared via nitroxide mediated polymerization in gradient polymer elution chromatography; iv) proving that scanning electron microscopy images are of limited value for assessing the macroporous properties of organic monoliths, and that pore measurements on externally polymerized monolith cocktails do not represent the porous properties of the same cocktail polymerized in narrow confinements; and v) showing that plasma bromination can be used as an activation step for rigid divinylbenzene particles to act as grafting handles for epoxy-containing telomers, that can be attached in a sufficiently dense layer and converted into carboxylate cation exchange layer that allows protein separations in fully aqueous eluents.

In this study, dendronization and grafting via controlled polymerization techniques, atom transfer radical polymerization (ATRP) and ring-opening polymerization (ROP), have been explored. Modification of surfaces and cellulose using these techniques, which enable grafting of well-defined polymer architectures, has been investigated. The interest in using cellulose stems from its renewability, biocompatibility, high molecular weight, and versatile functionalization possibilities. Dendronization was performed using disulfide-cored didendrons of 2,2-bis(methylol)propionic acid (bis-MPA) on gold surfaces, for the formation of self-assembled monolayers. It was found that the height of the monolayer increased with increasing dendron generation and that the end-group functionality controlled the wettability of the modified surface. Superhydrophobic cellulose surfaces could be obtained when a ‘graft-on-graft’ architecture was obtained using ATRP from filter paper after subsequent post-functionalized using a perfluorinated compound. The low wettability could be explained by a combination of a high surface roughness and the chemical composition. Biobased dendronized polymers were synthesized through the ‘attach to’ route employing dendronization of soluble cellulose, in the form of hydroxypropyl cellulose (HPC). The dendronized polymers were studied as nanosized objects using atomic force microscopy (AFM) and it was found that the dendron end-group functionality had a large effect on the molecular conformation on surfaces of spun cast molecules. ATRP of vinyl monomers was conducted from an initiator-functionalized HPC and an initiator-functionalized first generation dendron, which was attached to HPC. The produced comb polymers showed high molecular weight and their sizes could be estimated via AFM of spun cast molecules on mica and from dynamic light scattering in solution, to around 100-200 nm. The comb polymers formed isoporous membranes, exhibiting pores of a few micrometers, when drop cast from a volatile solvent in a humid environment. HPC was also used to initiate ROP of ε-caprolactone, which was chain extended using ATRP to achieve amphiphilic comb block copolymers. These polymers could be suspended in water, cross-linked and were able to solubilize a hydrophobic compound. / QC 20100826

Förfrågan efter nya och mer avancerade applikationer är en pågående process vilket leder till en konstant utveckling av nya material. För att förstå relationen mellan en applikations egenskaper och dess sammansättning krävs full förståelse och kontroll över materialets uppbyggnad. En sådan kontroll över uppbyggnaden hos material hittas i en undergrupp till dendritiska polymerer som kallas dendrimerer. I den här doktorsavhandlingen belyses nya metoder för att framställa dendrimer med hjälp av selektiva kemiska reaktioner. Sådana selektiva reaktioner kan hittas inom konceptet klickkemi och har i detta arbete kombinerats med traditionell anhydrid- och karbodiimidmedierad kemi. Denna avhandling diskuterar en accelererad tillväxtmetod, dendrimerer med inre och yttre reaktiva grupper, simultana reaktioner och applikationer baserade på dessa dendritiska material. En accelererad tillväxtmetod har utvecklats baserad på AB2- och CD2-monomerer. Dessa monomerer tillåter tillväxt av dendrimerer utan att använda sig av skyddsgruppkemi eller aktivering av ändgrupper. Detta gjordes genom att kombinera kemoselektiviteten hos klickkemi tillsammans med traditionell syraklorid kopplingar. Dendrimerer med inre alkyn- eller azidfunktionalitet syntetiserades genom att använda AB2C-monomerer. Den dendritiska tillväxten skedde med hjälp av karbodiimidmedierad kemi. Monomererna som användes bär på en C-funktionalitet, alkyn eller azid, och på så sätt byggs får interiören i de syntetiserade dendrimeren en inneburen aktiv funktionell grupp. Ortogonaliteten hos klickkemi användes för att sammanfoga monomerer till en dendritisk struktur. Traditionell anhydridkemi- och klickemireaktioner utfördes samtidigt och på så sätt kunde dendritiska strukturer erhållas med färre antal uppreningssteg. En ljusemitterande dendrimer syntetiserades genom att koppla azidfunktionella dendroner till en alkynfunktionell cyclenkärna. Europiumjoner inkorporerades i kärnan varpå dendrimerens fotofysiska egenskaper analyserades. Mätningarna visade att den bildade triazolen hade en sensibiliserande effekt på europiumjonen. Termiska studier på några av de syntetiserade dendrimerer utfördes för att se om några av dem kunde fungera som templat vid framställning av isoporösa filmer. / The need for new improved materials in cutting edge applications is constantly inspiring researchers to developing novel advanced macromolecular structures. A research area within advanced and complex macromolecular structures is dendrimers and their synthesis. Dendrimers consist of highly dense and branched structures that have promising properties suitable for biomedical and electrical applications and as templating materials. Dendrimers provide full control over the structure and property relationship since they are synthesized with unprecedented control over each reaction step. In this doctoral thesis, new methodologies for dendrimer synthesis are based on the concept of click chemistry in combination with traditional chemical reactions for dendrimer synthesis. This thesis discusses an accelerated growth approach, dendrimers with internal functionality, concurrent reactions and their applications. An accelerated growth approach for dendrimers was developed based on AB2- and CD2-monomers. These allow dendritic growth without the use of activation or deprotection of the peripheral end-groups. This was achieved by combining the chemoselective nature of click chemistry and traditional acid chloride reactions. Dendrimers with internal azide/alkyne functionality were prepared by adding AB2C monomers to a multifunctional core. Dendritic growth was obtained by employing carbodiimide mediated chemistry. The monomers carry a pendant C-functionality (alkyne or azide) that remains available in the dendritic interior resulting in dendrimers with internal and peripheral functionalities. The orthogonal nature of click chemistry was utilized for the simultaneous assembly of monomers into dendritic structures. Traditional anhydride chemistry and click chemistry were carried out concurrently to obtain dendritic structures. This procedure allows synthesis of dendritic structures using fewer purification steps. Thermal analyses on selected dendrimers were carried out to verify their use as templates for the formation of honeycomb membranes. Additionally, a light emitting dendrimer was prepared by coupling of azide functional dendrons to an alkyne functional cyclen core. A Europium ion was incorporated into the dendrimer core, and photophysical measurements on the metal containing dendrimer revealed that the formed triazole linkage possesses a sensitizing effect. / QC 20100629

<p>Polymers are subjected to physical and chemical changes during their processing, service life, and further recovery, and they may also interact with impurities that can alter their composition. These changes substantially modify the stabilisation mechanisms and mechanical properties of recycled polymers. Detailed knowledge about how the different stages of their life cycle affect the degree of degradation of polymeric materials is important when discussing their further waste recovery possibilities and the performance of recycled plastics. A dual-pronged experimental approach employing multiple processing and thermo-oxidation has been proposed to model the life cycle of recycled high-impact polystyrene (HIPS). Both reprocessing and thermo-oxidative degradation are responsible for coexistent physical and chemical effects (chain scission, crosslinking, apparition of oxidative moieties, polymeric chain rearrangements, and physical ageing) on the microstructure and morphology of polybutadiene (PB) and polystyrene (PS) phases; these effects ultimately influence the long-term stability, and the rheological and mechanical behaviour of HIPS. The PB phase has proved to be the initiation point of HIPS degradation throughout the life cycle. Thermo-oxidation seems to have more severe effects on HIPS properties; therefore, it can be concluded that previous service life may be the part of the life cycle with the greatest influence on the recycling possibilities and performance of HIPS recyclates in second-market applications. The results from the life cycle degradation simulation were compared with those obtained from real samples from a large-scale mechanical recycling plant. A combination of different analytical strategies (thermal analysis, vibrational spectroscopy, and chromatographic analysis) is necessary to obtain a detailed understanding of the quality of recycled HIPS as defined by three key properties: degree of mixing, degree of degradation, and presence of low molecular weight compounds.</p>

<p>The use of synthetic materials for tissue and organ reconstruction, i. e. tissue engineering, has become a promising alternative to current surgical therapies and may overcome the shortcomings of the methods in use today. The challenge is in the design and reproducible fabrication of biocompatible and bioresorbable polymers, with suitable surface chemistry, desirable mechanical properties, and the wanted degradation profile. These material properties can be achieved in various manners, including the synthesis of homo- and copolymers along with linear and star-shaped architectures. In many applications the materials’ three-dimensional structure is almost as important as its composition and porous scaffolds with high porosity and interconnected pores that facilitate the in-growth of cells and transportation of nutrients and metabolic waste is desired.</p><p>In this work linear and star-shaped polymers have been synthesized by ring-opening polymerization using a stannous-based catalyst and a spirocyclic tin initiator. A series of linear copolymers with various combinations of 1,5-dioxepane-2-one (DXO), Llactide (LLA) and ε-caprolactone (CL) have been polymerized using stannous octoate as catalyst. It is shown that the composition of the polymers can be chosen in such a manner that the materials’ mechanical and thermal properties can be predetermined. A solvent-casting and particulate leaching scaffold preparation technique has been developed and used to create three-dimensional structures with interconnected pores. The achieved physical properties of these materials’ should facilitate their use in both soft and hard tissue regeneration.</p><p>Well defined star-shaped polyesters have been synthesized using a spirocyclic tin initiator where L-lactide was chosen as a model system for the investigation of the polymerization kinetics. Neither the temperature nor the solvent affects the molecular weight or the molecular weight distribution of the star-shaped polymers, which all show a molecular weight distribution below 1.19 and a molecular weight determined by the initial monomer-to-initiator concentration.</p>

<p>Cross-linked films of ε-caprolactone (CL) and 1,5-dioxepan-2-one (DXO) having various mole fractions of monomers and different cross-link densities were prepared using 2,2’-bis-(-caprolactone-4-yl) propane (BCP) as cross-linking agent and Sn(Oct)2 as catalyst. Reaction parameters were examined to optimize the film-forming conditions. Networks obtained were elastomeric materials, easy to cast and remove from the mould. Effect of CL content and cross-link density on the final properties of the polymer network was evaluated. Thermal, mechanical and surface properties of the films were controlled by monomer feed composition and cross-link density. The films have potential to be used for tissue engineering applications as shown by preliminary cell growth studies. To avoid organometallic catalysts in the synthesis of poly(1,5-dioxepan-2-one) (PDXO), the enzyme-catalyzed ring-opening polymerization (ROP) of DXO was performed with lipase-CA (derived from Candida antarctica) as a biocatalyst. A linear relationship between number-average molecular weight (Mn) and monomer conversion was observed, which suggested that the product molecular weight can be controlled by the stoichiometry of the reactants. The monomer consumption followed a first-order rate law with respect to monomer and no chain termination occurred. Effect of reaction water content, enzyme concentration and polymerization temperature on monomer conversion and polymer properties was studied. An initial activation by heating the enzyme was sufficient to start the polymerization as monomer conversion occurred at room temperature afterwards. Terminal-functionalized polyesters and tri-block polyesters were synthesized by lipase-CA catalyzed ROP of DXO and CL in the presence of an appropriate alcohol as initiator. Alcohol bearing unsaturation introduced a double bond at the chain end of the polyester, which is a useful pathway to synthesize comb polymers. Dihydroxyl compounds were used as macro-initiators to form tri-block polyesters. The enzyme-catalyzed polymerization of lactones has been shown to be a useful method to synthesize metal-free polyesters.</p>

This thesis presents the results of computer simulation studies of the structure, dynamics, and deformation of cross-linked polymer gels. Obtaining a fundamental understanding of the interrelation between the detailed structure and the properties of polymer gels is a challenge and a key issue towards designing materials for specific purposes. A new off-lattice method for constructing a closed network is presented that is free from defects, such as looping chains and dangling ends. Using these model networks in Brownian dynamics simulations, I show results for the structure and dynamics of bulk gels and describe a novel approach using spherical boundary conditions as an alternative to the periodic boundary conditions commonly used in simulations. This algorithm was also applied for simulating the diffusion of tracer particles within a static and dynamic network, to illustrate the quantitative difference and importance of including network mobility for large particles, as dynamic chains facilitate the escape of particles that become entrapped. I further investigate two technologically relevant properties of polymer gels: their stimuli-responsive behaviour and their mechanical properties. The collapse of core-shell nanogels was studied for a range of parameters, including the cross-linking degree and shell thickness. Two distinct regimes of gel collapse could be observed, with a rapid formation of small clusters followed by a coarsening stage. It is shown that in some cases, a collapsing shell may lead to an inversion of the core-shell particle which exposes the core polymer chains to the environment. This thesis also explores the deformation of bimodal gels consisting of both short and long chains, subject to uniaxial elongation, with the aim to understand the role of both network composition as well as structural heterogeneity on the mechanical response and the reinforcement mechanism of these materials. It is shown that a bimodal molecular weight distribution alone is sufficient to strongly alter the mechanical properties of networks compared to the corresponding unimodal networks with the same number-average chain length. Furthermore, it is shown that heterogeneities in the form of high-density short-chain clusters affect the mechanical properties relative to a homogeneous network, primarily by providing extensibility.