Octafluorobiphenylene-linked bis(cyclopentadienone) was prepared bearing one perfluoro-4-tolyl and one tert-butyl substituent on the terminal diene rings. Polymerizations with 1,4- and 1,3-diethynylbenzene afforded linear Diels-Alder polyphenylenes (DAPPs) having lateral tert-butyl and perfluoro-4-tolyl substituents. The perfluoro-4-tolyl-substituted DAPPs are thermally stable, glassy solids (Tg ~ 230 deg C) that could not be cast into stable films (Mn ~ 10kDa, DPn ~ 10). New compounds perfluoro(1-phenyl-1-octanone) and perfluoro(1,1-diphenyl-1-octanol) were prepared from pentafluorophenylmagnesium bromide and perfluorooctanoyl chloride by nucleophilic acyl substitution and addition reactions. Diels-Alder reactions of 1,2-bis(nonafluorobiphenyl-4-yl)-4-tert-butylcyclopentadiene (CPD-1) with N-(4-fluorophenyl)maleimide (FMI) were explored as models for cyclopentadiene-maleimide-based Diels-Alder polymerizations. Mixtures of five endo/exo adducts were obtained, dependent upon CPD-1 tautomers present at reaction temperatures. The thermodynamic adduct (B3LYP/6-31G* geometry optimizations) was found to be the exo DA adduct of FMI and 2,3-bis(nonafluorobiphenyl-4-yl)-5-tert-butylcyclopentadiene. Five of the six possible isomers were observed and characterized including two by single-crystal X-ray diffraction. Parallel reactions of FMI and 1,2-bis(pentafluorophenyl)-4-tert-butylcyclopentadiene yielded three crystallographically characterized isomers, and with 1H NMR and 19F NMR spectrometry, including 1-D NOE, allowed five isomeric products to be identified. Diene CPD-1 is reactive toward nucleophiles (such as potassium 4-methylphenoxide) at the 4-positions of the C12F9 groups. Using this reactivity pattern, CPD-1 was polymerized with bis(phenol) A (BPA) and bis(phenol-A-6F) (BPAF) to form linear poly(arylene ethers) (Mn ~35 kDa) containing backbone cyclopentadienes. These polymers are glassy solids (Tg ~ 220 deg C) with good thermal stability (Td ~ 290 deg C), and they form stable, creaseable films cast from chloroform solutions. Treatment with 1.5-5.0% of 1,6-bis(N-maleimido)dodecane in N,N-dimethylacetamide (DMAc) at 165 deg C gave insoluble, solvent-swellable networks confirmed using ATR-FTIR. CPD-1 was also used as a cyclopentadiene-based linking group for chain extension of phenol-terminated methyl-PEEK oligomers (PEEKMOHs) with Mn values of 2, 5, and 10 kDa. These polymers are glassy solids (Tg ~ 156 deg C) with good thermal stability (Td ~ 400 deg C), that form stable, creaseable films from chloroform. Segmented polymers were treated with FMI in NMP, and showed functionalization density of approximately 50% by 19F NMR. Segmented polymers were also cross-linked by reaction of 1,6-bis(N-maleimido)hexane (cyclopentadiene to maleimide functional group ratio of 1:1) in NMP at 140 deg C. / Ph. D.

Telechelic associating polymer networks consist of polymer chains terminated by endgroups that have a different chemical composition than the polymer backbone. When dissolved in a solution, the endgroups cluster together to form aggregates. At low temperature, a strongly connected reversible network is formed and the system behaves like a gel. Telechelic networks are of interest since they are representative for biopolymer networks (e.g. F-actin) and are widely used in medical applications (e.g. hydrogels for tissue engineering, wound dressings) and consumer products (e.g. contact lenses, paint thickeners). In this thesis such systems are studied by means of a molecular dynamics/Monte Carlo simulation. At first, the system in rest is studied by means of graph theory. The changes in network topology upon cooling to the gel state, are characterized. Hereto an extensive study of the eigenvalue spectrum of the gel network is performed. As a result, an in-depth investigation of the eigenvalue spectra for spatial ER, scale-free, and small-world networks is carried out. Next, the gel under the application of a constant shear is studied, with a focus on shear banding and the changes in topology under shear. Finally, the relation between the gel transition and percolation is discussed.

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.

No description available.

PTMO-urethane and urea diacrylates (UtDA, UrDA) were synthesized from a two-step reactions of bis (4-isocyanatocyclohexyl) methane (HMDI) with either α,Ï -hydroxy-terminated poly (tetramethylene oxide) (PTMO Mn 250, 1000, 2000 and 2900 g/mol) or α,Ï -aminopropyl-terminated PTMO and 2-hydroxyethyl acrylate (HEA). PTMO-based ester precursors (EtDA) were also synthesized from α,Ï -hydroxy-terminated PTMO (Mn 1000 and 2000 g/mol). Two bis acetoacetates were synthesized from acetoacetylation of 1,4-butanediol and 250 g/mol hydroxy-terminated PTMO with tert-butyl acetoacetate. ¹H NMR spectroscopy confirmed the structure and average molecular weights (Mn)of diacrylates. Mn of these precursors were in the range of 950 to 3670 g/mol by ¹H NMR. The rheological properties of diacrylates were studied and activation energies for flow were calculated. Activation energies increased with increasing Mn and hydrogen-bond segment content. Michael carbon addition was employed to covalently crosslink the precursors resulting in networks with gel fractions better than 90%. DSC and DMA experiments revealed that networks had a broad distribution of glass transition temperatures depending on Mn and degree of hydrogen bonding present in the diacrylates. Their Tg's varied from -61 ºC to 63 ºC depending on the crosslinking density and hydrogen-bonding segment content. TGA revealed that UtDA and UrDA networks had an improved thermal stability compared to their EtDA counterparts. Tensile properties showed a variation depending on the structure and Mn of diacrylate and BisAcAc precursors. The storage moduli of networks precursor change from 25.3 MPa to 2.0 MPa with increasing Mn of the urethane diacrylate Elongation at break increased from 255% to 755 % for the same networks. The Young's moduli increased from 3.27 MPa for EtDA 2000 to 311.1 MPa for UrDA 2000 which was attributed to increasing degree of hydrogen-bonding. Acid functionalization of C70 P Baytubes multiwalled carbon nanotubes (MWCNT) generated acid-functionalized nanotubes (MWCNT-COOH). Suspension of MWCNT-COOH in organic solvents (chloroform, toluene, THF, DMF and 2-propanol) were prepared. DLS indicated average particle diameters of MWCNT-COOH in DMF and in 2-propanol were 139 nm and 162 nm respectively. FESEM of suspensions revealed aggregate free dispersion of MWCNT-COOH in DMF and 2-propanol. MWCNT-COOH containing composite networks were prepared. FESEM images of fracture surfaces of UtDA showed MWCNT-COOH were well-dispersed in the composites. DMA showed an increase in the rubbery plateau modulus which correlated with the MWCNT-COOH content in the networks. Tensile testing also revealed a relationship between MWCNT-COOH content and young's moduli and strain at break of networks. Storage moduli of networks increased from 25 MPa to 211 MPa with increasing MWCNT-COOH content whereas elongation at break decreased from 255 % to 146 %. UtDAs and pentaerythritol tetraacrylate (PETA) were crosslinked under UV radiation (6 passes, 1.42 ± 0.05 W.cm2 for each pass) in the presence of 2,2-dimethoxy-2-phenylacetophenone (DMPA) (1 wt. % of the mixture) UV initiator. DMA demonstrated the presence of broad glass transition regions with a range of Tg's which varied from -60 °C to -30°C. Tensile testing also revealed the relationship between Young's moduli, strain at break and the molecular weight of the diacrylates. The increasing molecular weight of urethane diacrylate precursors caused a drop in the storage moduli of networks from 15.8 MPa to 1.4 MPa and an increase in elongation at break from 76 % to 132 %. / Master of Science

Conjugated organic polymers have attracted immense interest for use in the active layer of photovoltaic cells, electroluminescent displays and diagnostic sensors. Precise control of the chemical structure of these conjugated materials is essential to achieve better device performance and certain structural aspects which have received minimal investigation include; the nature of the end groups, the precise control of the molecular weight and the formation of novel polymer topologies. Absolute control of these factors, in particular the end groups, has the potential to further tune the electro-optical properties, eliminate charge trapping and reactive sites, and facilitate block copolymer formation. The ring opening metathesis polymerisation of highly strained cyclophanediene monomers has proven to be an advantageous route to obtain soluble poly(p-phenylenevinylene)s (PPVs). In an extension of this previous work PPVs with both a pristine polymer backbone microstructure and a range of well-defined functional end groups have been prepared. These polymers exhibited excellent degrees of functionality, relatively narrow unimodal distributions and degrees of polymerisation much higher than those attainable by alternate routes. In particular the incorporation of an α-bromoester end group directly resulted in PPVs which were effective macroinitiators in the atom transfer radical polymerisation of methyl methacrylate. The diblock copolymers prepared by this route were isolated with narrow polydispersities, unimodal distributions and were free from homopolymer impurities. This method of preparing rod-b-coil diblock copolymers, where the properties of the two segments can readily be modified, provides access to materials which are of interest for both their self-assembly ability and for the development of a much required phase diagram in this area. Cyclic PPVs are of synthetic interest both for the absence of any end groups and for an infinitely long π-conjugated backbone, both of which are expected to contribute to unique electro-optical properties. The preparation of these target polymers was investigated by the ring expansion metathesis polymerisation of the cyclophanediene monomers. The formation of purely cyclic, low molecular weight PPVs was found to be highly dependent on both the reaction conditions used and the nature of the solubilising substituents. For example the preparation of purely cyclic PPVs with alkoxy side chains was unsuccessful, however the incorporation of alkyl side chains allowed for the successful isolation of the desired cyclic polymers.

Cette thèse concerne l’étude de phase de séparation de deux polymères thermosensibles connus-poly(N-isopropylacylamide) (PNIPAM) et poly(2-isopropyl-2-oxazoline) (PIPOZ). Parmi des études variées sur ces deux polymères, il y a encore deux parties de leurs propriétés thermiques inexplicites à être étudiées. Une partie concerne l’effet de consolvant de PNIPAM dans l’eau et un autre solvant hydromiscible. L’autre est l’effet de propriétés de groupes terminaux de chaînes sur la séparation de phase de PIPOZ. Pour ce faire, nous avons d’abord étudié l’effet de l’architecture de chaînes sur l’effet de cosolvant de PNIPAMs dans le mélange de méthanol/eau en utilisant un PNIPAM en étoile avec 4 branches et un PNIPAM cyclique comme modèles. Avec PNIPAM en étoile, l’adhérence de branches PNIPAM de à un cœur hydrophobique provoque une réduction de Tc (la température du point de turbidité) et une enthalpie plus faible de la transition de phase. En revanche, la Tc de PNIPAM en étoile dépend de la masse molaire de polymère. La coopérativité de déhydratation diminue pour PNIPAM en étoile et PNIPAM cyclique à cause de la limite topologique. Une étude sur l’influence de concentration en polymère sur l’effet de cosolvant de PNIPAM dans le mélange méthanol/eau a montré qu’une séparation de phase liquide-liquide macroscopique (MLLPS) a lieu pour une solution de PNIPAM dans le mélange méthanol/eau avec la fraction molaire de méthanol entre 0.127 et 0.421 et la concentration en PNIPAM est constante à 10 g.L-1. Après deux jours d’équilibration à température ambiante, la suspension turbide de PNIPAM dans le mélange méthanol/eau se sépare en deux phases dont une phase possède beaucoup plus de PNIPAM que l’autre. Un diagramme de phase qui montre la MLLPS pour le mélange PNIPAM/eau/méthanol a été établi à base de données expérimentales. La taille et la morphologie de gouttelettes dans la phase riche en polymère condensée dépendent de la fraction molaire de méthanol. Parce que la présence de méthanol influence la tension de surface des gouttelettes liquides, un équilibre lent de la séparation de phase pour PNIPAM/eau/méthanol système a été accéléré et une séparation de phase liquide-liquide macroscopique apparait. Afin d’étudier l’effet de groupes terminaux sur les propriétés de solution de PIPOZ, deux PIPOZs téléchéliques avec groupe perfluorodécanyle (FPIPOZ) ou groupe octadécyle (C18PIPOZ) comme extrémités de chaîne ont été synthétisés. Les valeurs de Tc des polymères téléchéliques ont beaucoup diminué par rapport à celle de PIPOZ. Des micelles stables se forment dans des solutions aqueuses de polymères téléchéliques. La micellization et la séparation de phase de ces polymères dans l’eau ont été étudiées. La séparation de phase de PIPOZs téléchéliques suit le mécanisme de MLLPS. Des différences en tailles de gouttelettes formées à l’intérieur de solutions de deux polymères ont été observées. Pour étudier profondément les différences dans le comportement d’association entre deux polymères téléchéliques, les intensités des signaux de polymères correspondants et les temps de relaxation T1, T2 ont été mesurés. Des valeurs de T2 de protons correspondants aux IPOZs sont plus hautes. / This thesis focused on the phase separation of two well-known thermoresponsive polymers, namely PNIPAM (poly(N-isopropylacrylamide)) and PIPOZ (poly(2-isopropyl-2-oxazoline). Despite various studies of the two polymers, two aspects of their thermal properties remained unclear and needed to be investigated. One is the cononsolvency effect of PNIPAM in water and a second water miscible solvent. The other is the effect of the end group properties on the phase separation of PIPOZ. With this in mind, we first studied the effect of the chain architecture on the cononsolvency of PNIPAM in water/methanol mixture, employing a 4-arm star shape PNIPAM and a cyclic PNIPAM as model. Tethering PNIPAM arms to a hydrophobic core resulted in a reduced Tc (cloud point temperature) and a lower phase transition enthalpy change. The Tc of the star shape PNIPAM was inversely dependent on the polymer molecular weight. The dehydration cooperativity was depressed for the star PNIPAM and cyclic PNIPAM due to topological constraints. A study of the effect of polymer concentration on the cononsolvency of PNIPAM in water/methanol mixture revealed a macroscopic liquid-liquid phase separation (MLLPS) for PNIPAM in water/methanol mixtures of methanol molar fraction ranging from 0.127 to 0.421 at a polymer concentration of 10 g·L-1. The turbid suspension of PNIPAM/water/methanol separated into a polymer rich phase coexisting with a polymer poor solution phase after equilibration for two days at room temperature. The phase diagram showing the MLLPS for the PNIPAM/water/methanol mixtures was constructed based on experimental data. The droplets in the condensed polymer rich phase showed a dependence on the methanol molar fraction. Methanol affects the surface tension of the liquid droplets. The slow equilibrium kinetics of PNIPAM phase separation was sped up and a macroscopic liquid-liquid phase separation realized. In order to study the effect of end groups on the solution properties of PIPOZ, two telechelic PIPOZ end capped with perfluorodecanyl groups (FPIPOZ) and octadecyl groups (C18PIPOZ), respectively, were synthesized. The Tc values of the telechelic polymers were greatly reduced after end-functionalization. Stable micelles formed in aqueous solutions of the telechelic polymers. The micellization and phase separation of the telechelic polymers in water were studied. The phase separation of the telechelic PIPOZs in water followed a liquid-liquid phase separation mechanism. Differences in the sizes of droplets formed inside of the two polymer solutions were observed. To further investigate the differences in the association behaviour between the two telechelic polymer, NMR signal intensities and T1 and T2 relaxation times were examined. Higher 1H T2 values were obtained for the IPOZ unit in FPIPOZ than that in C18PIPOZ, indicating a higher mobility of the main chain in the FPIPOZ micelles than that in the C18PIPOZ micelles. Together with the 13C NMR and 19F NMR relaxation studies, we obtained better knowledge of the association properties of the telechelic PIPOZ in water. NMR relaxation studies proved to be efficient way of probing the solution behaviour of the polymers.

Certain hydrogel forming de novo proteins that utilize different crosslinking methods are studied experimentally on a rheometer. The stress reaxation modulus of CRC, a telechelic, triblock protein, is shown to be that of a stretched exponential function with a value of β ≅ 0.5. The insertion of an integrin binding domain and changes in pH within the range 6.5–8.5 are shown not to significantly affect the resulting rheological behavior. A selective chemical crosslinker is used on CRC hydrogel systems and is shown to change the rheological behavior of the system to that of a combination of a chemically and physically crosslinked system. Chemically crosslinked hydrogels composed of W6, a wheat gluten-based protein, demonstrate a storage modulus weakly dependent on the angular frequency that is much greater than the loss modulus, with a modulus concentration dependence of c^9/4.

Certain hydrogel forming de novo proteins that utilize different crosslinking methods are studied experimentally on a rheometer. The stress reaxation modulus of CRC, a telechelic, triblock protein, is shown to be that of a stretched exponential function with a value of β ≅ 0.5. The insertion of an integrin binding domain and changes in pH within the range 6.5–8.5 are shown not to significantly affect the resulting rheological behavior. A selective chemical crosslinker is used on CRC hydrogel systems and is shown to change the rheological behavior of the system to that of a combination of a chemically and physically crosslinked system. Chemically crosslinked hydrogels composed of W6, a wheat gluten-based protein, demonstrate a storage modulus weakly dependent on the angular frequency that is much greater than the loss modulus, with a modulus concentration dependence of c^9/4.

Certain hydrogel forming de novo proteins that utilize different crosslinking methods are studied experimentally on a rheometer. The stress reaxation modulus of CRC, a telechelic, triblock protein, is shown to be that of a stretched exponential function with a value of β ≅ 0.5. The insertion of an integrin binding domain and changes in pH within the range 6.5–8.5 are shown not to significantly affect the resulting rheological behavior. A selective chemical crosslinker is used on CRC hydrogel systems and is shown to change the rheological behavior of the system to that of a combination of a chemically and physically crosslinked system. Chemically crosslinked hydrogels composed of W6, a wheat gluten-based protein, demonstrate a storage modulus weakly dependent on the angular frequency that is much greater than the loss modulus, with a modulus concentration dependence of c^9/4.