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Study On The Synthesis And Properties Of Hydrophobically Modified Polyacrylamides And Its Associating Morphology In Solution

Posted on:2005-03-27Degree:DoctorType:Dissertation
Country:ChinaCandidate:C R ZhongFull Text:PDF
GTID:1101360152470022Subject:Materials science
Abstract/Summary:PDF Full Text Request
The nonionic hydrophobically associating water-soluble copolymers (abbreviation: PSAM) of styrene derivatives (abbreviation: STD) and acrylamide (abbreviation: AM) were synthesized by micellar free radical copolymerization technique, while STD is the first time to be used as the hydrophobic monomer against the literature reported. And the ionic copolymer (abbreviation: PASA) was prepared by incorporating the third monomer sodium-2-acrylamido-2-methylpropane sulphonate (abbreviation: NaAMPS) to the molecule structure of PSAM. The two key problems including the very poor water-solubility and heat stability of the hydrophobically associating water-soluble polymers are overcome by this study.During the synthesis of PSAM and PASA, SDS was selected as the surfactant for the micellar polymerization, and the effects of all the reaction conditions on monomer conversion, intrinsic viscosity and the viscosification performance of the polymer solution were studied, and the suitable reaction parameters were obtained. The synthesized product was proved to be the target copolymer by the molecule structure and composition characterization. GPC measurement indicates that the molecular weight of both PSAM and PASA is not high, the block-structure of the two copolymers was proved by DSC measurement, and by TG analysis, PSAM shows very good heat stability, while it's even better for PASA.PASA copolymers displayed excellent water-solubility and viscosification property, which are better than the reference literature reported. The apparent viscosities of both PSAM and PASA are improved remarkably by addition of verysmall amount of the surfactant such as SDS, SDBS and CTAB, and the effect of CTAB on PASA property in brine solution is obviously stronger than SDS and SDBS. It took about one hour for the solid sample of PASA to dissovle in water. The PASA aqueous solution showed excellent storage stability under the temperature of 45, and the apparent viscosity remained unchanging with time. PASA displayed excellent heat stability while its solution with high NaCl concentration aged under 70 D for 30 days and 85 ? for 15 days, and the apparent viscosity increased substantially with time.The kinetics study of the copolymerization of AM and STD shows that the reactivity ratio of AM and STD is r1=0.76, r2=8.55 respectively, which indicates that STD has very high homopolymerization activity. It is found that the polymerization kinetics of acrylamide in aqueous solution can still be applied in the micellar copolymerization process, and the initial conversion of STD is higher than that of AM, which results in the micro-structure homogeneity of STD in the copolymer molecules, leading to the decrease of the thickening properties of PASA. Therefore, the content of hydrophobic monomer and the distribution heterogeneity in the copolymer molecules could be improved effectively by stepwisely feeding of STD or controlling of the hydrophobic monomer /surfactant ratio .The flourescence probe of PASA indicates that the polyer molecules have strong hydrophobically associating effects in pure water and NaCl solution, and the nonpolarity of hydrophobic microstructures become stronger, and the hydrophobic microstructures turn more condensed by the addition of NaCl. The dynamic concentration Cs) of the copolymer PASA is 0.005g/dL, and the non-polarity of the polyer aqueous solution dropped with the increase of polymer concentration. The viscosity measurement of the microenvironment of the polymer solution shows that the microviscosity of"0.05g/dL polymer solution is very high.The studies of dynamic light scattering show that PASA copolymer molecules mainly exist in the form of single molecule in the polymer aqueous solution with the 0.005g/dL polymer concentration. In 0.01-0.2g/dL polymer concentration, thehydrodynamic radiuses(Rh) distribution consists of two regions: single molecules and hydrophobic associating molecules . The distribution of Rh in 0.3g/dL PASA aqueous solution was mono-disperse,and only aggregates exist. The number of aggregates with Rh...
Keywords/Search Tags:Hydrophobically Modified Polyacrylamide, Styrene Derivative, Hydrophobic Association, Micelle Copolymerization, Solution Properties, Flourescence Probe, Environmental Scanning Electron Microscope, Dynamic Light Scattering, Atomic Force Microscope
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