To investigate the influence of structure variables of polymeric additives on the pour-point depression and rheological behavior of waxy crude oil, maleic anhydride co-polymer and its derivatives with different polar and/or aromatic pendant chains were designed and synthesized. All prepared additives were characterized by Fourier transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC). The pour-point and rheological properties of Changqing (CQ) crude oil with a low asphaltene content before and after additive beneficiation were studied in detail. Differential scanning calorimetry (DSC) and polarizing light microscopy were employed to gain insight on the interactions between such additives and wax crystals. The results are encouraging and showed that all four polymeric additives exhibited good efficiency as flow improvers in CQ crude oil. The reduction of pour-point and rheological parameters after additive addition largely related to the polymer structure. The polymer containing aromatic units showed the best performance, which could depress the pour point by 19 °C and decrease the yield stress as well as viscosity to a large extent.

Reverse atom transfer radical copolymerization of styrene (St) and butyl acrylate was carried out in emulsion under normal emulsion conditions, using CuBr 2 / bpy complex as catalyst. The effects of surfactant type, initiator type and concentration, and CuBr 2 addition on the system livingness, polymer molecular weight control, and latex stability were examined in detail. It was found that the Polysorbate 80 (Tween 80) and azodiisobutyronitrile gave the best exhibition in this system, polymer samples were got with narrow molecular-weight dispersity (M w /M n ¼ 1.1-1.2) and linear relationships of molecular weight versus monomer conversion, as well as a relatively low polydispersity index (<0.1). Through the GPC and SEM analysis, the polymerization processes under these conditions showed good living/control characteristics relative to the processes under normal emulsion polymerization, although the latex stability was susceptible to the CuBr 2 catalyst.