Abstract
Low molecular weight compounds were used to model the reaction between a range of substituted methyl-ketones with hydrazides in comparison to amines. The reactions were studied by 1H-NMR spectroscopy at three pH values, in order to establish structure-reactivity relationships and pH control of the reaction. The information gained was used to design four acrylate monomers containing a terminal methyl-ketone moiety. The monomers were incorporated into a methyl methacrylate and n-butyl acrylate polymer backbone at low concentrations. The methyl-ketone group was expected to engage in crosslinking reactions with a water-soluble dihydrazide crosslinker. Tests were performed to show the effect on polymer film properties when such a reaction occurs. Swelling studies were carried out to show the extent of reaction in polymer samples through calculation of the average molecular weight between crosslinks. Mc. An introduction to emulsion polymers and their application in binder compositions is given in chapter 1. Several condensation processes known to occur between carbonyl- and amino-functional groups in different structures, and under different conditions, are also outlined. The experimental procedures and analytical techniques used throughout the research are described in chapter 2. In chapters 3 and 4, model systems were used to determine details of the condensation process (in a dilute aqueous environment) and control of the reaction by pH. This knowledge was applied in chapter 5 to the design of polymer systems which may be crosslinked through such condensations. The resulting systems were compared to a commercially available crosslinking emulsion polymer composition to test their relative performance. These various aspects are discussed at the end of the thesis with suggestions for further research.