| Double hydrophilic block copolymers (DHBCs) are composed of two water-soluble blocks with different chemical properties:one block just promotes dissolution; whereas the other interacts with a certain substrate, which can be designed with appropriate functional group. Double hydrophilic block copolymers are water-soluble and friendly to the environment, which agree with the development of ecology and society. In this doctoral dissertation, brief research background of this work is introduced, in which the history and recent progress in double hydrophilic block copolymer are reviewed from a worldwide angle of view. The objective and the scientific significance of this doctoral dissertation are also pointed out. In our work, a series of double hydrophilic block copolymers with polyethylene glycol have been synthesized and their properties have been investigated. The details and key conclusions are summarized as follows:(1) The macroazoinitiator PEG-ACPC was synthesized by polyethelene glycol and 4,4’-azobis(4-cyano pentanoic acid). A series of double hydrophilic multiblock copolymer poly(ethylene glycol)-b-poly(2-acrylamido-2-methyl propanesulfonic sodium) (PEG-b-PAMPSNa) were synthesized by radical polymerization of 2-acrylamido-2-methyl propanesulfonic sodium (AMPSNa) and PEG-ACPC. The structures of the PEG-b-PAMPSNa were confirmed by 1H-NMR, FT-IR and elemental analysis. The composition of the copolymers was determined by elemental analysis. The molecular weight and dispersity were determined by gel permeation chromatography combined with multiangle laser light scattering (GPC-MALLS), and the value of Rg/Rh, which could confirm the chain structure of the copolymer, was also obtained from the GPC-MALLS result. The result showed that the molecular weight and the flexibility of the copolymer increased with the PEG contents. It was because that the presence of PEG weakened the steric hindrance and ion-exclusion effect of AMPSNa.The aggregation behaviors of the copolymer in aqueous solution and salt solution were studied by dynamic laser light scattering. The aggregation of PEG-b-PAMPSNa in aqueous solution had great relationship with the copolymer composition and concentration, which was mainly due to the strong ion-exclusion effect of sulfonic group in PAMPSNa block. But in 0.1 mol/L NaCl the presence of plenty countra-ion, which shield the ion-exclusion effect, made the copolymer aggregated as common neutral polymers. When the NaCl concentration increased to a point, the aggregation was inhibited greatly and hard to assemble in solution.PEG-b-PAMPSNa was used as mineralization template for the crystal growth of barium sulfate. The size and morphology had great changes with the increase of copolymer concentration. It indicates that the copolymer was an effective mineralization template for barium sulfate. It was thought that the copolymer has various formations in its aqueous solution at different concentrations, which made barium sulfate crystals with different morphologies formed.(2) Poly(ethylene glycol)-b-poly(sodium 4-styrenesulfonate) (PEG-b-PSSS) was synthesized by radical polymerization of sodium 4-styrenesulfonate and PEG-ACPC which prepared by PEG2000 and PEG4000.The structures of the PEG-b-PSSS were confirmed by 1H-NMR, FT-IR and elemental analysis. The compositions of PEG2000-b-PSSS and PEG4ooo-b-PSSS were determined by elemental analysis. The molecular weight and dispersity were determined by gel permeation chromatography combined with multiangle laser light scattering (GPC-MALLS), and the result showed that the molecular weight had no crucial difference for PEG2000-b-PSSS and PEG4000-b-PSSS, the molecular weight increased with the PSSS content. The value of Rg/Rh, which could confirm the chain structure of the copolymer, was also obtained from the GPC-MALLS result. The result showed that the molecular weight and the flexibility of the copolymer increased with the PEG contents.PEG-b-PSSS was used as mineralization template for the crystal growth of barium sulfate. The influences of copolymer concentration, pH of solution, aging time and [Ba2+]/[SO42-] ratio were studied. The copolymer concentration had great influence to the crystal size and morphology. With the increase of copolymer concentration, the crystals tend to be spherical. The other conditions had less influence to the growth of barium sulfate.(3) Poly(ethylene glycol)-b-poly(methacylic acid-co-4-vinyl benzylamine hydrochloride salt) (MPEG-b-PMAA/PVBAHS) was synthesized by radical polymerization of Methacylic acid,4-vinyl benzyl amine hydrochloride salt and MPEG-ACPC which prepared by Poly(ethylene glycol) monomethyl ether and 4,4’-azobis(4-cyano pentanoic acid). The structures of the MPEG-b-PMAA/PVBAHS were confirmed by 1H-NMR, FT-IR and elemental analysis. The thermal stability of MPEG-b-PMAA/PVBAHS was studied, and the side chain was more stable with increase VBAHS content. It was mainly due to the formation of inner salt and crosslinking increased with more VBAHS content.The solution properties of MPEG-b-PMAA/PVBAHS were studied by spectrophotometer, dynamic laser light scattering and florescence. MPEG-b-PMAA/PVBAHS was pH-responsive. The isoelectric point (IEP) and pH titration curves were determined. The copolymer was insoluble in water at isoelectric point. At a certain pH the copolymer could form big aggregation. For the MPEG-b-PMAA/PVBAHS with MAA and VBAHS ratio, spherical aggregation could be observed by transmission electron microscope (TEM) when the pH around the IEP. When the pH was far away from the IEP, the big aggregation hardly formed in the copolymer aqueous solution.(4) A series of poly(ethylene glycol)-b-polymethacrylamide (MPEG-b-PMAM) with different compositions were synthesized. The structures of the MPEG-b-PMAM were confirmed by 1H-NMR, FT-IR and elemental analysis. The thermal stability of the side chain of MPEG-b-PMAM inceased with the MAM content, but the thermal stability of the main chain decreased with the MAM content.The solution properties of MPEG-b-PMAM were studied by dynamic laser light scattering, transmission electron microscope (TEM) and florescence. With the potentiometric titration, there was an obvious complexation effect between Ca2+ and MPEG-b-PMAM. And the complexation effect had great relationship with the composition of the copolymer:it was more effective with increasing MPEG content. The copolymer was taken as the mineralization template for the growth of calcium carbonate. It revealed that the morphology of calcium carbonate could be controlled by MPEG-b-PMAM at different pH in the solution. The calcium carbonate crystals with different morphologies were all confirmed to be calcite structure. It indicated that MPEG-b-PMAM only had influence to the morphology of calcium carbonate crystal, the crystal form had no change.(5) Poly(ethylene glycol)-b-poly (N,N-dimethyl-N-methacryloyloxyethyl-N-(3-sulfo-propyl) ammonium) (MPEG-b-PDMPS) was synthesized by radical polymerization of macroazoinitiator MPEG-ACPC and N,N-dimethyl-N-methacryloyloxyethyl-N-(3-sulfo-propyl) ammonium. The structures of the MPEG-b-PDMPS were confirmed by 1H-NMR, FT-IR and elemental analysis. The thermal stability of the side chain of MPEG-b-PDMPS increased with the PDMPS content.The solution properties of MPEG-b-PDMPS were studied by spectrophotometer, dynamic laser light scattering and florescence. The influence of copolymer concentration, salt and pH of the solution to the aggregation behaviors were studied. From the transmission electron microscope (TEM) result, the ratio of MPEG to PDMPS in the copolymer had crucial influce to the aggregation structure in the solution. |
PDF Full Text Request