Synthesis And Surface Properties Of Amphiphilic Linear-dendritic Carbosilane Block Copolymers

In this paper, based on allylation of hydroxyl-terminated PEG and hydrosilylation of the allylic double bonds, two kind of linear-dendritic amphiphilic block copolymers with carbosilane hydrophobic head groups attached to PEG hydrophilic bridging chain were synthesized. Studied the surface behavior and solution assemblies situation.The first part of this paper mainly covered the synthesis and characterization of amphiphilic linear-dendritic carbosilane block copolymers. This paper used organic silicon group as hydrophobic portion and polyethylene glycol as hydrophilic portion, with the consist of platinum catalyst through allylation and hydrosilylation synthesized two kind of LDBCs. The molecular structures of the LDBCs were characterized with 1H NMR,13C NMR and FT-IR. In addition, the paper studied the influence of the reaction temperature, time and molar ratio. Steric effect the hydrosilylation of triethylsilane with double bonds. With the secondly generation dendritic, the allyl double bond can only react with triethylsilane about 66%(mole percent). The hydrosilylation is still incomplete by introducing an N-containing compound (triethylamine as the ligand or use pyridine as solvent) in the reaction system. Part of the double bond not participate in the hydrosilation reaction.The second part described the surface/interfacial properties and hydrolysis stability of the linear-dendritic amphiphilic block copolymers. The two copolymers showed good surface activities, and the CAC values are 5.13×10-4 and 4.83×10-5 mol·L-1,γCAC values are 32.48 and 32.21 mN·m-1 respectively. Moreover, two breaks were observed in the surface tension vs concentration curve for the two copolymers, which is believed to originate from rearrangement of the copolymer molecules on the air/water surface, and the molecular architecture of the copolymers at the surface layer were effected by the PEG segments and carbosilane branched blocks of the copolymers. The two copolymers showed good hydrolysis stability. The surface tension of solutions with 0.1 wt.%standing 15 days in 0.115 mol·L-1 HCl and 0.102 mol·L-1 NaOH environment were increased about 9%.