The research presented focused on the synthesis and the characterization of graft polymers, of interest either as model systems or for large-scale applications. The materials selected as substrates for grafting reactions were carbosilane dendrimers, linear and branched polystyrenes, and cross-linked polystyrene latex particles. The synthesis of dendrimer-arborescent polymer hybrids was thus achieved by derivatization of the carbosilane dendrimers with dichlorosilane moieties and coupling with 1,4-polybutadiene side chains with Mn ≈ 1000. A second derivatization and coupling reaction with Mn ≈ 1500, 5000, or 30000 side chains yielded hybrid polymers with narrow molecular weight distributions (Mw/Mn ≤ 1.16). In the second part of the thesis, a procedure for the large-scale (100-g) synthesis of arborescent styrene homopolymers and copolymers incorporating poly(2-vinylpyridine) segments is presented. End-capping of the polystyryllithium chains with 1,1-diphenylethylene in the presence of LiCl, followed by the addition of 3 – 6 equivalents of 2-vinylpyridine per side chain, eliminated side reactions and led to grafting yields of up to 95 %. A systematic investigation of the solution properties of polyelectrolytes obtained by protonation of the poly(2-vinylpyridine) arborescent copolymers with a strong acid (trifluoroacetic acid) is also presented. The relative importance of the electrostatic repulsion and the elastic deformation forces on molecular expansion was investigated by examining the solution properties of the copolymers as a function of structure, protonation level, and the presence of salts in polar solvents (methanol, DMF, H2O). The viscosity of the arborescent copolymer solutions was also found to be much lower than for linear P2VP samples under the same conditions. In the last part of the thesis, the synthesis of model filler particles was achieved by grafting polyisoprene chains onto cross-linked polystyrene latex particles derivatized with acetyl coupling sites. These substrates, which can be viewed as an extreme case of a dense (hard-sphere) arborescent polymer structure, were used to investigate the influence of filler-matrix polymer interactions on the rheological behavior of filled polyisoprene samples. The influence of the filler structure on the rheological behavior of the blends was examined by dynamic mechanical analysis in terms of frequency-dependent complex viscosity, storage modulus, and damping factor. All the blends exhibited enhanced complex viscosity, storage modulus, and decreased damping factor values relative to the matrix polymer.

The research presented focused on the synthesis and the characterization of graft polymers, of interest either as model systems or for large-scale applications. The materials selected as substrates for grafting reactions were carbosilane dendrimers, linear and branched polystyrenes, and cross-linked polystyrene latex particles. The synthesis of dendrimer-arborescent polymer hybrids was thus achieved by derivatization of the carbosilane dendrimers with dichlorosilane moieties and coupling with 1,4-polybutadiene side chains with Mn ≈ 1000. A second derivatization and coupling reaction with Mn ≈ 1500, 5000, or 30000 side chains yielded hybrid polymers with narrow molecular weight distributions (Mw/Mn ≤ 1.16). In the second part of the thesis, a procedure for the large-scale (100-g) synthesis of arborescent styrene homopolymers and copolymers incorporating poly(2-vinylpyridine) segments is presented. End-capping of the polystyryllithium chains with 1,1-diphenylethylene in the presence of LiCl, followed by the addition of 3 – 6 equivalents of 2-vinylpyridine per side chain, eliminated side reactions and led to grafting yields of up to 95 %. A systematic investigation of the solution properties of polyelectrolytes obtained by protonation of the poly(2-vinylpyridine) arborescent copolymers with a strong acid (trifluoroacetic acid) is also presented. The relative importance of the electrostatic repulsion and the elastic deformation forces on molecular expansion was investigated by examining the solution properties of the copolymers as a function of structure, protonation level, and the presence of salts in polar solvents (methanol, DMF, H2O). The viscosity of the arborescent copolymer solutions was also found to be much lower than for linear P2VP samples under the same conditions. In the last part of the thesis, the synthesis of model filler particles was achieved by grafting polyisoprene chains onto cross-linked polystyrene latex particles derivatized with acetyl coupling sites. These substrates, which can be viewed as an extreme case of a dense (hard-sphere) arborescent polymer structure, were used to investigate the influence of filler-matrix polymer interactions on the rheological behavior of filled polyisoprene samples. The influence of the filler structure on the rheological behavior of the blends was examined by dynamic mechanical analysis in terms of frequency-dependent complex viscosity, storage modulus, and damping factor. All the blends exhibited enhanced complex viscosity, storage modulus, and decreased damping factor values relative to the matrix polymer.

Graft copolymers with a dendritic (arborescent) architecture and unimolecular micelle properties have been synthesized and examined for their solution properties as well as their ability to serve as templates for the preparation of metallic nanoparticles. The research focused on two types of arborescent copolymers, namely core-shell (CS) and core-shell-corona (CSC) architectures. Copolymer amphipolarity was provided by a hydrophobic polystyrene (PS) component and a polar poly(2-vinylpyridine), P2VP, phase. The CS copolymers were obtained by grafting P2VP onto linear or branched PS substrates to yield PS-g-P2VP unimolecular micelles. These copolymers exhibited solubility with limited aggregation in aqueous environments after protonation with HCl. Coordination of the coronal P2VP phase with HAuCl4 was achieved, and the resulting polymer-stabilized metallic nanoparticles had a spherical morphology. The tri-layered copolymers were synthesized in similar fashion, by grafting PS-b-P2VP block copolymers onto linear or branched PS substrates to afford a CSC morphology with a PS core, a P2VP inner shell, and a PS corona. While the grafting reaction proceeded with lower than expected grafting yields as compared to grafting reactions of homopolymer side-chains, significant P2VP content and molecular weight increases were achieved. It was determined that aggregation of the block copolymer side-chains hindered the coupling reaction of the reactive centers with the substrate. After purification of the PS-g-(P2VP-b-PS) arborescent copolymers, in part by developing a cloud-point centrifugation purification technique, the spherical copolymers were successfully loaded with various metallic compounds. The uptake of compounds such as HAuCl4 by the P2VP phase of the copolymers induced intramolecular phase segregation for copolymers of generations (G) 2 and above. Phase segregation produced some unique and intricate morphologies different from the ones observed previously for other unimolecular metal scaffolds. Intramolecular toroidal, nodular, and cylindrical morphologies were observed for the G2, G3, and G4 arborescent copolymers, respectively. Templates of generations 0 and 1 displayed a spherical morphology similar to their PS-b-P2VP intermolecular micelle analogues when loaded with metals. Phase segregation is believed to be mediated mainly by the characteristics of the PS core, the length of the P2VP segments having less influence on the morphologies obtained. Reduction of the metallic salts was performed using various agents and protocols. Stronger reducing agents yielded smaller and more narrowly distributed gold nanoparticles, while other reduction methods also removing the polymer scaffold resulted in larger nanoparticles.

Graft copolymers with a dendritic (arborescent) architecture and unimolecular micelle properties have been synthesized and examined for their solution properties as well as their ability to serve as templates for the preparation of metallic nanoparticles. The research focused on two types of arborescent copolymers, namely core-shell (CS) and core-shell-corona (CSC) architectures. Copolymer amphipolarity was provided by a hydrophobic polystyrene (PS) component and a polar poly(2-vinylpyridine), P2VP, phase. The CS copolymers were obtained by grafting P2VP onto linear or branched PS substrates to yield PS-g-P2VP unimolecular micelles. These copolymers exhibited solubility with limited aggregation in aqueous environments after protonation with HCl. Coordination of the coronal P2VP phase with HAuCl4 was achieved, and the resulting polymer-stabilized metallic nanoparticles had a spherical morphology. The tri-layered copolymers were synthesized in similar fashion, by grafting PS-b-P2VP block copolymers onto linear or branched PS substrates to afford a CSC morphology with a PS core, a P2VP inner shell, and a PS corona. While the grafting reaction proceeded with lower than expected grafting yields as compared to grafting reactions of homopolymer side-chains, significant P2VP content and molecular weight increases were achieved. It was determined that aggregation of the block copolymer side-chains hindered the coupling reaction of the reactive centers with the substrate. After purification of the PS-g-(P2VP-b-PS) arborescent copolymers, in part by developing a cloud-point centrifugation purification technique, the spherical copolymers were successfully loaded with various metallic compounds. The uptake of compounds such as HAuCl4 by the P2VP phase of the copolymers induced intramolecular phase segregation for copolymers of generations (G) 2 and above. Phase segregation produced some unique and intricate morphologies different from the ones observed previously for other unimolecular metal scaffolds. Intramolecular toroidal, nodular, and cylindrical morphologies were observed for the G2, G3, and G4 arborescent copolymers, respectively. Templates of generations 0 and 1 displayed a spherical morphology similar to their PS-b-P2VP intermolecular micelle analogues when loaded with metals. Phase segregation is believed to be mediated mainly by the characteristics of the PS core, the length of the P2VP segments having less influence on the morphologies obtained. Reduction of the metallic salts was performed using various agents and protocols. Stronger reducing agents yielded smaller and more narrowly distributed gold nanoparticles, while other reduction methods also removing the polymer scaffold resulted in larger nanoparticles.