Modification of the paraffin crystallization and flow ability of waxy crude oil is of vital importance during transportation and restart processes at low temperature. To investigate the influence of pendants in comb-type copolymers on the cold flow ability of crude oil, maleic anhydride-α-octadecene copolymer and its derivatives with octadecyl (MAC), phenyl (AMAC), or naphthalene (NMAC) pendants were synthesized. These derivatives, when added to waxy crude oil, change the size and quantity of the paraffin crystals observed by polarizing light microscopy (PLM), improve the flow ability of waxy oils by reducing the viscosity and yield stress revealed by rheometer, and decrease the paraffin crystallization temperature and quantity of wax precipitation determined by differential scanning calorimetry (DSC). AMAC had the greatest effect followed by MAC and NMAC, respectively. It seems that small aromatic pendants improve the flow ability of waxy oils by adsorbing on the surface of asphaltenes, while large aromatic pendants impair the assembly of copolymers with asphaltenes by a higher steric hindrance.

Recent studies of the high energy‐conversion efficiency of the nanofluidic platform have revealed the enormous potential for efficient exploitation of electrokinetic phenomena in nanoporous membranes for clean‐energy harvesting from salinity gradients. Here, nanofluidic reverse electrodialysis (NF‐RED) consisting of vertically aligned boron‐nitride‐nanopore (VA‐BNNP) membranes is presented, which can efficiently harness osmotic power. The power density of the VA‐BNNP reaches up to 105 W m−2, which is several orders of magnitude higher than in other nanopores with similar pore sizes, leading to 165 mW m−2 of net power density (i.e., power per membrane area). Low‐pressure chemical vapor deposition technology is employed to uniformly deposit a thin BN layer within 1D anodized alumina pores to prepare a macroscopic VA‐BNNP membrane with a high nanopore density, ≈108 pores cm−2. These membranes can resolve fundamental questions regarding the ion mobility, liquid transport, and power generation in highly charged nanopores. It is shown that the transference number in the VA‐BNNP is almost constant over the entire salt concentration range, which is different from other nanopore systems. Moreover, it is also demonstrated that the BN deposition on the nanopore channels can significantly enhance the diffusio‐osmosis velocity by two orders of magnitude at a high salinity gradient, resulting in a huge increase in power density.

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Adding comb copolymers as chemical additives is considered an effective and convenient method to improve the cold flow ability of crude oils. To improve the effectiveness of comb copolymers on the flow ability modification for crude oils with asphaltenes, poly(maleic acid amide-α-octadecene) with benzimidazolyl pendants (MACB) were designed and synthesized. In comparison to reported comb maleic anhydride copolymers (MAC) with octadecyl (MACO) or phenyl (MACP) pendants, MACB with heteroaromatic pendants are more efficient in reducing the yield stress of both model oil and Liaohe crude oil, as revealed by rheological measurements, in modifying the morphology of wax crystals, as observed by polarizing light microscopy (PLM), in lowering the wax appearance temperature (WAT) and quantity of wax precipitation, as determined by differential scanning calorimetry (DSC), and in decreasing the crystallinity of paraffins, as measured by X-ray diffraction (XRD). The benzimidazolyl pendants in MACB can provide both hydrogen bonding by amino groups and π−π stacking by benzyl groups with asphaltenes in crude oil, which improves the interactions with asphaltens and, thus, the effectiveness in modification the cold flow ability of crude oils.