Organotin polymers as components for marine anti-fouling paints

Abstract

The work described in this thesis is concerned with the synthesis of di-n-alkyl bis(hydroxy carboxylate)tin monomers and their reactions with several di- and poly-functional isocyanates to give polyurethanes with tin carboxylate units in the polymer backbone. These polymers were prepared for evaluation as components of marine anti-fouling paints. The first chapter reviews the causes of marine fouling and the methods currently used to reduce corrosion and fouling. The synthesis and characterisation of the di-n-alkyl bis(hydroxy carboxylate)tin monomers required for this work are described in Chapter Two; their polymerisation with commercial di- or poly-functional isocyanates being described in Chapter Three. The polymers prepared by the methods described in Chapter Three were tested using an apparatus designed by the author which simulated a ship's passage through the water, this work is discussed in Chapter Four. The first set of polymers prepared (Chapter Three) were unable to withstand the physical stresses to which they were subjected and so a new set of co-polymers was synthesised using the organotin diols and commercially available diols as comonomers. The synthesis and testing of these copolymers is described in Chapter Five. The polymers prepared in Chapter Five were generally good film forming materials, their hardness being easily controlled, however their inclusion into paint systems was impracticable due to the ease of their hydrolysis and subsequent loss of film integrity.