Synthesis and characterisation of polythersulphone poly(dimethyl siloxane) block copolymers.

The objectives of this project were to investigate synthetic routes to form block copolymers of polyethersulphone and polydimethylsiloxane, linked through =Si-C= bonds.The work carried out has included the synthesis and characterisation of hydroxyl terminated polyethersulphone oligomers (PES). This material has then been quantitatively functionalised to give vinyl ended PES.A number of hydride terminated polydimethylsiloxane oligomers (PDMS) have also been synthesised and characterised. These materials have been successfully functionalised with epoxy groups through a vinyl addition reaction in the presence of chloroplatinic acid catalyst, incorporating the =Si-C= bond into the PDMS.These polymers, along with purchased carboxy propyl PDMS allowed the investigation of three principle routes to PES/PDMS copolymers (i) the catalysed addition reaction of vinyl PES with hydride terminated PDMS. (ii) the reaction of hydroxyl terminated PES with epoxy functionalised PDMS. (iii) the condensation reaction of hydroxyl terminated PES with carboxy propyl PDMS in the presence of stannous octoate catalyst.All three routes produce (A-B)[n] PES/PDMS block copolymers linked through =Si-C= bonds.Due to the large difference in solubility parameters between PES and PDMS homopolymers, there is great difficulty in producing a homogeneous solution of the reacting polymers. A wide range of solvent systems were investigated before 1,1,2,2-tetrachloroethane (TCE) was found to be the most suitable. Routes (i) and (ii) were investigated as solution reactions in TCE and the reaction products characterised by proton nuclear magnetic resonance spectroscopy (1-H nmr) and differential scanning calorimetry (dsc). Both reactions showed only limited success. Route (iii) could not be investigated in solution as a homogeneous solution of the oligomers could not be formed.All three synthetic routes were investigated as reactions in the melt and the products characterised by 1-H nmr and dsc. Routes (ii) and (iii) proving to be the more successful.All three reaction schemes were examined extensively using model compounds and short chain polymeric oligomers and were shown to be suitable routes to form the required block copolymers.