Understanding the interactions between siloxane polymer melts and polysilicate resin particles is of great importance where practical applications of the properties of polymerbased materials are regulated by the presence of particles. One of these industrial applications for siloxane polymers is as antifoaming agents; most efficient antifoams consist of a dispersion of colloidal particles in silicone and!or mineral oil. Some of these antifoams are small �?« 10 nm) species known in the industry as MQ resins, the chemical properties of these particles are between small silica particles and highly cross-linked silicone polymers. This work involves the use of Nuclear Magnetic Resonance and Neutron Reflection techniques to study the effect of adding nanopolysilicate resins to polysiloxane polymer melts to elucidate the structure of water-polymer-air interfaces in order to identify the specific location of the nanoparticles. Different particle sizes and concentrations of nanopolysilicate resin were used. The results from 1H nuclear magnetic resonance T2 relaxation spectroscopy showed that the nanopolysilicate resin reinforced low molecular weight PDMS but solvated high molecular PDMS melts. The critical entanglement molecular weight was also calculated for the PDMS melt and nanopolysilicate resin! PDMS blends, it was found to be independent of temperature. Neutron reflectometry results highlighted the hydrophobic character of the nanopolysilicate particles and that the particles accumulate in the air! polymer interface. The adsorbed amount of resin on the surface was found to be dependent on the particle size and concentration. This behaviour was also observed in the surface tension and Langmuir trough results.
|Date of Award||2007|