The Design and Synthesis of Dendrimers for Applications in the Pulp & Paper Industry

Dendrimers find applications in many diverse fields including biology, catalysis, the pulp and paper industry, etc. The distinctive properties of dendrimers leading to their wide applicability include tailorability and high surface group density. In this thesis the design and synthesis of water soluble dendrimers for potential applications as anti-scalants and bactericides, two important areas within the pulp and paper industry, are explored. The dendrimers were constructed on a tetrafunctional core which allows us to obtain a higher number of end groups at a lower generation than in the bi- and trifunctional cores generally employed. We utilized "click" chemistry, or more specifically the copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) reaction, for both dendrimer synthesis and post-functionalization. The implementation of this methodology required the selection of appropriate acetylene- and azide-terminated building blocks. For this purpose we chose i) an acetylene-terminated molecule having a carboxylic acid end group; and ii) an azide-terminated building block with a diol group at its other end. Using a divergent synthetic methodology in which the azide unit was first linked to the tetrafunctional acetylene core, followed by an esterification with the carboxylic acid group of the acetylene-terminated building block, we constructed acetylene-terminated dendrimers of generations 1-3. Generations 0-2 with terminal acetylene groups were subsequently functionalized with cationic amino groups for an evaluation of their behaviour as bactericides, and phosphonate groups for potential application as anti-scalants. The cationic amino-functionalized dendrimers, G0-NH3+, G1-NH3 + and G2-NH3+, as well as one of the OH-terminated dendrimers, G1, were then evaluated for their bactericidal efficacy. The generation one dendrimer, G1-NH 3+, was found to be the most effective bactericide. Additionally it was determined to be more potent than several previously studied dendrimers. The deprotection of the phosphonate-terminated dendrimers from their ethyl esters to the corresponding alcohols was found to be cumbersome, and prevented their evaluation as anti-scalants.