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A novel approach to synthesize narrow particle size distribution cationic latex particles based on styrene and butyl acrylate was proposed. The effect of monomer/water ratios, surfactant (cetyltrimethylammonium chloride) concentrations, and monomer compositions on the evolution of particle size, distribution, number, and morphology as a function of monomer conversion was concerned in order to confirm the optimum polymerization condition. As expected, the particle size of the ultima latex increased with monomer/water ratios and styrene contents decreased with increasing surfactant concentrations. Continuous nucleation phenomena occurred when monomer/water ratio was lesser than 30/70, resulting in a gradual increase in the number of particles in the whole polymerization process. Combined with the previous work (Colloid and Polymer Science, 2014, 292: 519–525), it was concluded that particle coagulation easily took place in cationic emulsion polymerization of styrene. Thus, the narrow particle size distribution cationic latexes with particle scale between 50 nm and 80 nm, 30 wt% solid content could be prepared in a short reaction time. [ABSTRACT FROM PUBLISHER]

A novel amphiphilic polymer, APAM, for enhanced oil recovery (EOR), was synthesized by radical copolymerization of acrylamide, dodecyl polyoxyethylene acrylate (DPEA), and N-(1,1,3,3-tetramethyl butyl) acrylamide (TBA), using potassium persulfate-sodium bisulfite as initiator-activator. The aggregation morphological observation of APAM in aqueous and NaCl solutions was performed using scanning electron microscope. The ability of APAM to solubilize and emulsify n-heptane and crude oil was investigated by visual methods, microscopy, and particle size analyses. The results show that APAM forms supramolecular aggregates in aqueous and NaCl solutions and has strong emulsification ability. As a result, the emulsion consisting of APAM aqueous solution and n-heptane (or crude oil) is much more stable than that of HPAM (partially hydrolyzed polyacrylamide, widely used in EOR), indicating a important function of APAM to emulsify oil component. [ABSTRACT FROM AUTHOR]

Nonionic gemini surfactants HBA(EO)80 were synthesized and characterized by means of surface tension measurements. CMCs of two mixed system, nonionic gemini mixed with anionic gemini (HBA(EO)80/C11pPHCNa) and nonionic gemini mixed with anionic monomeric (HBA(EO)80/SL) and the effect of salt on the two mixed system were investigated. Freeze-fracture transmission electron microscopy and scanning electron microscopy were used to investigate the mixed aggregates' morphologies. The results show that large spherical aggregates were formed in the mixed solution, which trend to transfer into micelles with the increases of the salt concentration. [ABSTRACT FROM AUTHOR]

Rheologic properties and the conformations of the mixed system of hydrophobically modified polyacrylamide and surfactants in distilled water with or without NaCl were investigated. The vacuum sublimation freezing-drying technique was employed to maintain the aggregation state of the mixed systems. Scan electron microscopy and transmission electron microscopy were used to investigate microstructure of the mixed systems formed, and obtain the system molecular configuration information. The results showed that the rheologic behavior of the mixed solution revealed by viscosity data and microconformation obtained depend on the salt existence and the hydrophobic group content of the polymer. The relationship between polymer microconformation and the macroscopic properties for the mixed systems was analyzed to explore the aggregating mechanism. [ABSTRACT FROM AUTHOR]

With the vacuum sublimation freezing-drying and rheological techniques, the salt/alkali/surfactant effects on the solution properties and the aggregate conformations of the polymers, synthesized hydrophobically modified poly (acrylamide) (HMPAM), were investigated. The experimental methods included viscosity measurements, the photomicroscopy, scan electron microscopy, and the freeze fracture transmission electron microscopy. The variety of conformations of the ultramolecular aggregates, the hydrophobical region, and the spatial network structures resulted from the hydrophobical interaction were studied. Combined results confirmed that HMPAM could form several of interesting three-dimensional network structures either in distilled water or NaCl solution. The results have revealed the mechanism of the salt/alkali/surfactant effects on the peculiar rheological properties of the solution. [ABSTRACT FROM AUTHOR]

The viscous properties, scanning electronic microscopy (SEM), and water/oil interfacial tension (IFT) of partially hydrolyzed polyacryamide (HPAM) and hydrophobically associating hydrolyzed polyacryamides modified with N-dodecylacrylamide were studied with the objective of investigating the influence on destabilization of emulsions. As expected, the copolymers exhibit significant viscosity enhancing capacity and three-dimensional network structures due to intermolecular hydrophobic associations, and also present high interfacial activities as the IFT decrease with increasing polymer concentration. As a result, the existences of copolymers increased both the viscosity of emulsions and the intensity of interfacial film, in which case slow down the diffusion of demulsifier molecules and enhance the stability of emulsions, finally, the separation of water from oil becomes more difficult. [ABSTRACT FROM AUTHOR]