Cylindrical brush polymers with poly-L-lysine side chains were prepared by grafting lysine NCA from a macroinitiator via living ring-opening polymerization. The main chain degree of polymerization of the methacrylate main chain was P w = 870, the side chains consisted of 25 and 55 lysine repeat units, respectively. Upon deprotection, the cylindrical brush polymers in 0.005 M NaBr exhibited an almost rodlike conformation with a Kuhn statistical segment length of several hundred nanometers. Cryo-TEM as well as AFM in aqueous solution clearly demonstrated pronounced undulations along the main chain at low ionic strength which could not be detected at higher salt concentrations. With increasing concentration of NaClO 4 the PLL side chains underwent a coil-to-helix transition as revealed by CD measurements. The effect of the side chain coil-to-helix transition on the main chain stiffness could not be followed by light scattering due to intramolecular attraction ("folding") of the cylindrical brushes at high salt concentration, which is somewhat more pronounced for the helical as compared to the coiled PLL side chain conformation. Comparison with linear PLL revealed the coil-to-helix transition to be hardly affected by the high grafting density of the PLL side chains in the cylindrical brush structures.

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Transportation of waxy crude oils and mitigation of wax deposition are major challenges especially in regions with cold climate. A viable solution for minimizing organic precipitation and fouling in pipelines or storage tanks is the use of inhibitors and dispersants, however, often those pour point depressants (PPDs) have their own challenges due to their own high product pour points. To overcome these issues a series of high active winterized polymer micro-dispersions were developed. Composition and physical properties of several light to heavy waxy crudes were fully explored based on SARA analysis, wax content and paraffin carbon chain distribution. Performance of candidate chemistries from four major classes of polymeric paraffin inhibitors were studied using industry standard methods. Selected high performing chemistries were processed into micro-dispersions using solvents and surfactants under high shear/ high pressure blending. The new polymer micro-dispersions (MDs) were characterized by their pumpability and stability at cold climates. Series of pour point measurements, rheology profiles and wax deposition tests were carried out for performance comparison of MDs to standard polymers in solution. Processes developed here were versatile to convert polymers from all classes of chemistries into micro-dispersion. Binary and ternary polymeric dispersions were also created showing synergistic effects on the pour point reduction and inhibition of wax deposition of the selected challenging crude oils. The performance of the new polymer micro-dispersions was found comparable to superior with standard polymers in solution. Hence, it was possible to create pumpable inhibitors for extreme cold climates without compromising on performance. The systematic approach used here allowed development of more customized solution based on crude characteristics and desired performance. Micro-dispersions were found stable for long term storage in temperatures ranging from -50°C to +50°C. Multiple global field trials are on-going with very positive results demonstrating early success in lab-to-field deployment. Based on lab and field data, this paper demonstrates that highly active micro-dispersed polymers can perform at significantly lower dosage rate when compared to winterized polymers in solution. Cold storage stability and pumpability eliminated the needs for heated tanks and lines reducing operation and capital expenditures.