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Liquid carbon dioxide (LCO2) or supercritical carbon dioxide (ScCO2) can be used as an important solvent medium for preparing polymer particles through dispersion polymerization. However, based on the weak solvent characteristics of CO2, the development of stabilizers used in dispersion polymerization has always been an important challenge. These stabilizers are progressing toward the low‐cost, pollution‐free, and simple synthesis routes, et al. In this research, pentaerythritol tetra (3‐mercaptopropionate) (PTMP) is used to control the homopolymerization or copolymerization of vinyl acetate (VAc)/vinyl propionate (VPr), the homopolymers or copolymers with thiol group are synthesized by the one‐pot method. These homopolymers or copolymers are used as the stabilizers to stabilize the dispersion polymerization of N‐vinyl‐2‐pyrrolidone (NVP) in ScCO2. The results show that the structural unit proportion of the stabilizers, the concentration of stabilizers or 2, 2´‐azobis(isobutyronitrile) (AIBN), and the time interval for dispersion polymerization have significant impacts on the conversion percentage of NVP and the molecular weight of polymers. The maximum conversion percentage of NVP can get to 95%, and the molecular weight of poly(N‐vinyl‐2‐pyrrolidone)(PNVP) can reach 22.3 kPa. SEM analysis indicates that the PNVP obtained has regular spherical characteristics. [ABSTRACT FROM AUTHOR]

A new strategy was developed to build a CO2-philic/hydrophilic surfactant by combining the common free radical polymerization and the grafting modification technology, and a brush polymer was synthesized with poly(vinyl acetate)(PVAc) based copolymer as the CO2-philic group (as the main chain) and the methoxy poly(ethylene glycol) (mPEG) as the hydrophilic part (as the branched chain) (PVAc-g-mPEG). The CO2-philic ability can be controlled by adjusting the chain length of the CO2-philic fragment. The results indicate that PVAc-g-mPEG has excellent surfactant activity, and can emulsify the CO2/H2O system to obtain the CO2-in-water (C/W) high interval phase emulsion (HIPE 80%, v/v), which can remain stable for more than 20 h. If using the monomers/crosslinking agent solution instead of water, the highly porous monolithic materials will be obtained after the continuous phase is polymerized. In this paper, polyacrylamide (PAM) and poly(acrylamide/diethyl aminoethyl methacrylate) (PADM)-based porous monolithic materials were prepared. These materials were used to remove bovine serum albumin (BSA, as the model matter) from the solution, and the results indicated that PAM-based porous monolithic materials had almost no enrichment capacity for protein, while PADM-based porous monolithic materials can adsorb BSA up to 129.3 mg/g. [ABSTRACT FROM AUTHOR]

The separation of the proteins is of great theoretical and practical importance for biotechnological application. Considering the requirement of non‐destructive separation, the stimulus–response method is an alternative to the separation of protein. In this work, a cellulose‐based composite with CO2 stimulus–response property is prepared by a simple coprecipitation of poly (N, Nˊ‐diethylamino ethyl methacrylate)‐co‐poly (hydroxyethyl methacrylate) (PDH) and cellulose mixture solution. Subsequently, these composites as the adsorption medium are used to separate the bovine serum albumin (BSA, as the model protein) from solution through stimulus–response course (by CO2/N2 alternation). The results indicate that the ratio of the copolymers/cellulose composite have an obvious effect on the separation of BSA. The average maximum adsorption capacity can get to 562.6 mg/g, and the composites exhibits good adsorption/desorption cycling characteristics. After the composite materials are cycled for three times, the adsorption capacity can still decrease to 300 mg/g. Due to its high adsorption capacity and low preparation cost, the composite is expected to be widely used in industry. [ABSTRACT FROM AUTHOR]