The Synthesis Of Structued Amphiphilic Polymer And Its Appliction In Preparation Of Nano-silica

Amphiphilic polymer as a surface active functional materials has attracted much attention due to the hydrophilic group and hydrophobic groups contained in the molecular structure at the same time, and amphiphilic polymer with regular structure especially has great value in many areas such as nano-materials, bio-medicine and so on. In this paper, the amphiphilic polymer with regular structure PtBMA-b-PAA was prepared by the method of catalytic chain transfer polymerization(CCTP) with low dosage of the metal catalysts and reversible addition-fragmentation chain transfer polymerization(RAFT) with the narrow molecular-weight distribution of the products, and it is applied to prepare nano-silica as a macromolecular surfactant by the method of reverse microemulsion at the first time.The synthesis of catalytic chain transfer agent was selectived as the first part for the CCTP. Benzil and hydroxylamine hydrochloride were used to sythetize α-benzildioxime selectively, and the yield of α-benzildioxime was improved from 65% to 83.5% through the optimization of reaction conditions. The α-benzildioxime obtained before, cobalt acetate and boron trifluoride were used to prepare CoBFPh by complexation without water and oxygen, and the yield of CoBFPh was 83.9%. t-BMA with the catalyst CoBFPh polymerized to a series of Pt-BMA(C=C) by altering the dosage of catalyst. The molecular weight Mn of t-BMA was 5081 ~ 9839. The polydispersity index(PDI) of t-BMA was1.61~1.77.The common synthesis process of RAFT reagent(CDB) was improved, and the yield of CDB was increased from 25% to 45.6%. t-BMA with the catalyst CDB polymerized to a series of structued PtBMA-CDB by altering the dosage of catalyst. The molecular weight Mn of PtBMA-CDB was 1062~8391, and the polydispersity index(PDI) of t-BMA was1.14 ~ 1.33. The structued PtBMA-b-PAA was perpared by PtBMA-CDB(Mn=3304,PDI=1.14) and AA, which Mn was 4091~6474 and the PDI was 1.24~1.32. The kinetic of polymerization process analysis indicated that the polymerization of t-BMA under the controlling of CDB and the copolymerization of PtBMA-CDB and AA ware controlled/living radical polymerization, which indicated that the PtBMA-b-PAA with the controlled chain length and neat structure could be obtained under the appropriate proportion of raw materials.The PtBMA-b-PAA obtained before as surfactant was uesd to prepare nano-silica by reverse microemulsion method. The minimum amount of PtBMA-b-PAA was 2.0g duringthe configuration process of reverse microemulsion, and minimum amount of market small molecule surfactant was 4.0g, which indicated that PtBMA-b-PAA had more excellent emulsifying properties. The nano-silica which prepared by PtBMA-b-PAA with different hydrophilic chain segment was spherical and had high dispersibility. And the particle size range of nano-silica 145nm~272nm, which was clearly different from the nano-silica that prepared by small molecule surfactant(10nm~110nm).