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The synthesis of a variety of novel functionalized polymers using living polymerization techniques to achieve functional and stimuli responsive coatings on silica surfaces are described. Since microscopic features on a surface influence the overall wetting properties of the surface, a systematic investigation of the influence of polymer architecture on the microscopic characteristics of the modified surfaces was studied using silane-functionalized linear and novel star-branched polystyrene (PS). Star-branched modifiers provide functional and relatively well-defined model systems for probing surface properties compared to ill-defined highly branched systems and synthetically challenging dendrimers. Using these simple star-shaped macromolecules it was shown that the topographies of the polymer-modified surfaces were indeed influenced by the polymer architecture. A model explaining the observed surface features was proposed. A living polymerization strategy was also used to synthesize centrally functionalized amphiphilic triblock copolymers. The amphiphilic copolymers exhibited stimuli responsive changes in surface hydrophobicity. In spite of multiple solvent exposures, the copolymer films remained stable on the surface indicating that the observed changes in surface properties were due to selective solvent induced reversible rearrangement of the copolymer blocks. The chemical composition of the copolymers was tailored in order to tune the response time of the surface anchored polymer chains. Thus, the polymer coatings were used to reversibly change the surface polarities in an on-demand fashion and could find possible applications as smart adhesives, sensors and reusable membrane devices. In contrast to the afore-mentioned covalent modification approach, which often leads to permanent modification of surfaces, renewable surfaces exhibiting "universal" adhesion properties were also obtained through non-covalent modification. By employing hydrogen bonding interactions between DNA bases, surfaces functionalized with adenine groups were found to reversibly associate with thymine-functionalized polymers. This study describing the solvato-reversible polymer coating was the first demonstration on silica surfaces. A systematic investigation of the influence of surface concentration of the multiple hydrogen bonding groups and their structure on the extent of polymer recognition by the modified surfaces is also discussed. / Ph. D.

<p>This thesis describes the synthesis and characterization ofbranched semi-crystalline polymers. Included in this work isthe SEC characterization of a series of dendrimers. Thebranched semi-crystalline polymers were synthesized in order toinvestigate the concept of their use as powder coatings resins.This concept being that the use of branched semi-crystallinepolymers in a UV-cured powder coating system may offer a lowertemperature alternative thus allowing the use of heat sensitivesubstrates and the added benefit of a reduced viscositycompared to linear polymers.</p><p>A series of branched poly(ε-caprolactone)’s (PCL)(degree of polymerization: 5-200) initiated from hydroxylfunctional initiators were synthesized. The final architectureswere controlled by the choice of initiator structure;specifically the dendritic initiators yielded starbranchedPCL’s while the linear initiator yielded comb-branchedPCL’s. The dendritic initiators utilized were: (1) a3rd-generation Boltorn H-30, commercially availablehyperbranched polyester with approximately 32 hydroxyl groups,(2) a 3rd-generation dendrimer with 24 hydroxyl groups, and (3)a 3rd-generation dendron with 8 hydroxyl groups. Linear PCL wassynthesized for comparison. All dendritic initiators are basedon 2,2- bis(methylol) propionic acid. The comb-branchedpolymers were initiated from a modified peroxide functionalpolyacrylate. The resins were end-capped withmethylmethacrylate in order to produce a cross-linkable system.The polymers and films were characterized using 1H NMR, 13CNMR, SEC, DMTA, DSC, FT-IR, FT-Raman, rheometry and a rheometercoupled to a UV-lamp to measure cure behavior.</p><p>The star-branched PCL’s exhibited considerably lowerviscosities than their linear counterparts with the samemolecular weight for the molecular region investigated (2-550kg mol-1). It was also found that the zero shear viscosityincreased roughly exponentially with M.</p><p>The PCL star-branched resins are semi-crystalline and theirmelting points (Tm) range from 34-50°C; films can beformed and cured below 80°C. The viscoelastic behaviourduring the cure showed that the time to reach the gel point, afew seconds, increased linearly with molecular weight. Thecrossover of G’and G’’was used as the gelpoint. Measurement of mechanical properties of films showedthat the low molecular weight polymers were amorphous whilethose with high molecular weight were crystalline after cure.The polymerization of 5,5-dimethyl-1,3-dioxane-2-one (NPC) fromoligo- and multifunctional initiators was evaluated utilizingcoordination and cationic polymerization. Two tin basedcatalysts, stannous(II) 2-ethylhexanoate and stannous(II)trifluoromethane sulfonate, were compared with fumaric acid.Fumaric acid under bulk conditions resulted in lowerpolydispersity and less chance of gelling. The synthesis ofstar-branched polymers was confirmed by SEC data. The starpolymers exhibited a Tg at 20-30°C and a Tm at about100°C.</p><p>All semi-crystalline resins exhibited a fast decrease inviscosity at Tm. Blends of combbranched semi-crystalline resinsand amorphous resins exhibited a transition behavior inbetweenthat of pure semi-crystalline resins and that of amorphousresins.</p><p>The SEC characterization of a series of dendrimers withdifferent cores and terminal groups showed that the core had animpact on the viscosimetric radius of the core while theterminal groups appeared to have no effect.</p><p><b>Keywords:</b>star-branched, semi-crystalline,comb-branched, ring-opening polymerization,poly(ε-caprolactone), dendritic, thermoset, lowtemperature curing, powder coating, UVcuring,poly(5,5-dimethyl-1,3-dioxane-2-one), size exclusionchromatography, rheology, dendritic aliphatic polyester</p>

This thesis describes the synthesis and characterization ofbranched semi-crystalline polymers. Included in this work isthe SEC characterization of a series of dendrimers. Thebranched semi-crystalline polymers were synthesized in order toinvestigate the concept of their use as powder coatings resins.This concept being that the use of branched semi-crystallinepolymers in a UV-cured powder coating system may offer a lowertemperature alternative thus allowing the use of heat sensitivesubstrates and the added benefit of a reduced viscositycompared to linear polymers. A series of branched poly(ε-caprolactone)’s (PCL)(degree of polymerization: 5-200) initiated from hydroxylfunctional initiators were synthesized. The final architectureswere controlled by the choice of initiator structure;specifically the dendritic initiators yielded starbranchedPCL’s while the linear initiator yielded comb-branchedPCL’s. The dendritic initiators utilized were: (1) a3rd-generation Boltorn H-30, commercially availablehyperbranched polyester with approximately 32 hydroxyl groups,(2) a 3rd-generation dendrimer with 24 hydroxyl groups, and (3)a 3rd-generation dendron with 8 hydroxyl groups. Linear PCL wassynthesized for comparison. All dendritic initiators are basedon 2,2- bis(methylol) propionic acid. The comb-branchedpolymers were initiated from a modified peroxide functionalpolyacrylate. The resins were end-capped withmethylmethacrylate in order to produce a cross-linkable system.The polymers and films were characterized using 1H NMR, 13CNMR, SEC, DMTA, DSC, FT-IR, FT-Raman, rheometry and a rheometercoupled to a UV-lamp to measure cure behavior. The star-branched PCL’s exhibited considerably lowerviscosities than their linear counterparts with the samemolecular weight for the molecular region investigated (2-550kg mol-1). It was also found that the zero shear viscosityincreased roughly exponentially with M. The PCL star-branched resins are semi-crystalline and theirmelting points (Tm) range from 34-50°C; films can beformed and cured below 80°C. The viscoelastic behaviourduring the cure showed that the time to reach the gel point, afew seconds, increased linearly with molecular weight. Thecrossover of G’and G’’was used as the gelpoint. Measurement of mechanical properties of films showedthat the low molecular weight polymers were amorphous whilethose with high molecular weight were crystalline after cure.The polymerization of 5,5-dimethyl-1,3-dioxane-2-one (NPC) fromoligo- and multifunctional initiators was evaluated utilizingcoordination and cationic polymerization. Two tin basedcatalysts, stannous(II) 2-ethylhexanoate and stannous(II)trifluoromethane sulfonate, were compared with fumaric acid.Fumaric acid under bulk conditions resulted in lowerpolydispersity and less chance of gelling. The synthesis ofstar-branched polymers was confirmed by SEC data. The starpolymers exhibited a Tg at 20-30°C and a Tm at about100°C. All semi-crystalline resins exhibited a fast decrease inviscosity at Tm. Blends of combbranched semi-crystalline resinsand amorphous resins exhibited a transition behavior inbetweenthat of pure semi-crystalline resins and that of amorphousresins. The SEC characterization of a series of dendrimers withdifferent cores and terminal groups showed that the core had animpact on the viscosimetric radius of the core while theterminal groups appeared to have no effect. Keywords:star-branched, semi-crystalline,comb-branched, ring-opening polymerization,poly(ε-caprolactone), dendritic, thermoset, lowtemperature curing, powder coating, UVcuring,poly(5,5-dimethyl-1,3-dioxane-2-one), size exclusionchromatography, rheology, dendritic aliphatic polyester / <p>NR 20140805</p>