A novel approach for the preparation of organic-siloxane oligomers and the creation of hydrophobic surface

In this paper, poly(acrylate- g-siloxane) with novel comb-like structure was designed and prepared so as to create a strongly hydrophobic polymer surface. In order to achieve this goal, a series of organic-siloxane oligomers with different chain lengths and a double bond were firstly synthesized through the catalytic reforming and hydrosilylation reaction. Then, poly(acrylate- g-siloxane) was prepared by the copolymerization of the resulting oligomers with acrylate via emulsion polymerization. The as-synthesized oligomers were characterized by 1H NMR and UV spectrometry, and the morphologies and surface chemical compositions of the dried membrane were investigated by FT-IR, XPS, as well as AFM. XPS analysis result shows that the chemical composition of the membrane's surface was rich in polysiloxane segments, which could be responsible for an increase of surface water repellency (the contact angle could reach 115° at a lower content of polysiloxane). A further investigation suggest that the side chain length of siloxane in the poly(acrylate- g-siloxane) was the dominant factor in influencing the hydrophobicity of the membrane’ surface. When the siloxane chain length reaches to eight, the membrane's surface could exhibit the strongest hydrophobicity.