Studies Of The Preparation Of Monodispersed PDMS Silicon Oil/water Emulsion And The Interaction With Nonionic-surfactants

In this work, the principles and characteristics of the photon correlation spectrum (PCS) measurement about particle size distribution and Zeta potential of nanometer systems have been expounded, and monodispersed polydimethylsilane(PDMS) oil/water emulsions are successfully prepared. The influence of nonionic surfactants TritonX-100, TritonX-405 on the stability and Zeta potential of the PDMS emulsion are analyzed. Based on those analyses, we study the interaction between the emulsion and the nonionic surfactants. The major content and conclusions can be described briefly as follows:1. The photon correlation spectrum system of particle size distribution and Zeta potential of nanometer systems are dissertated , and principles , characteristics, equipments and uncertainties of the measurement are adressed.2. Emulsions prepared under acidic conditions are compared with emulsion prepared under basic conditions. Under acidic conditions emulsion has a small average count rate, emulsion particles grow slowly at the early stage and quickly at the latter, with lower zeta potential. However, under basic conditions, those parameters are contrasted. At the same time there is a plateau in which particles almost don't grow. We give an explanation according to principles of emulsion polymerization. Based on the seed-free emulsion polymerization ofdimethyldiethoxysilane in basic condition, mono-disperse polydimethylsilane (PDMS) emulsions are prepared with polydispersity at 0.05 and effective diameter at about 1000nm.3. Experiments have been done to study the law about Zeta potential of PDMS against PH values. The result shows that :the absolute value of the Zeta potential increases with PH. Based on the result, we conclude that :the Zeta potential of PDMS not only relates to the hydroxyl but also to the adsorption of OH- on the lattices interface.4.The influence of Tritonx-100,Tritonx-405 on the Zeta potential of PDMS emulsion are studied. Zeta potential of emulsions is higher frst and then decrease to a plateau with nonionic surfactant concentration increasing. We put forward the reason by analyzing the hydrophobic of the emulsion drop interface and the shield effect of Tritonx-100 and Tritonx-405.5. The influence of Tritonx-100, Tritonx-405 on the stability of PDMS emulsion are studied Adsorption of nonionic surfactant can improve the emulsion stability .However, when Tritonx-100 concentration exceeds 30μmol/L, count rate of emulsions dramatically increases and average diameter of emulsion particles decreases. Those phenomena aren't observed for emulsions added with Tritonx-405. Based on the difference between the interface tension values of the lattices adsorped Tritonx-100 and Tritonx-405,an explanation is given.