Dependence of intrinsic viscosity and molecular size on molecular weight of partially hydrolyzed polyacrylamide

Abstract

As a typical water-soluble polymer, ultra-high molecular weight (UHMW) partially hydrolyzed polyacrylamide (HPAM) has been widely used in various industries as thickeners or rheology modifiers. However, precise determination of its critical physical parameters such as molecular weight, radius of gyration (R g ) and hydrodynamic radius (R h ) were less documented due to their high viscosity in aqueous solution. In this work, the molecular structure of five UHMW-HPAM samples with different MW was elucidated by 1 H and 13 C NMR spectroscopy, and their solution properties were characterized by both static and dynamic light scattering. It is found that all the second virial coefficient (A 2 ) values are positive and approaching zero, indicating of a good solvent of 0.5 M NaCl for UHMW-HPAM. The weight-average molecular weight (M w ) dependence of molecular size and intrinsic viscosity [η] for these series of HPAM polymers with MW ranging from 4.81 to 15.4 × 10 6 gÁmol −1 can be correlated as R g = 3.52 × 10 −2 M w 0.51 , R h = 1.97 × 10 −2 M w 0.51 , and [η] = 6.98 × 10 −4 M w 0.91 , respectively. These results are helpful in understanding the relationship between molecular weight and coil size of HPAM polymers in solution, and offer references for quick estimation of molecular weight and screening of commercial UHMW-HPAM polymers for specific end-users.

Elastic turbulence generates anomalous flow resistance in porous media

“…We also use this quantity to estimate the mean polymer radius of gyration R g using the relation c* ≈ (M w /V)/N A , where M w is the polymer molecular weight, V = 4 R g 3 / 3 is the volume occupied by a single polymer molecule, and N A is Avogadro's number (59), yielding R g ≈ 220 nm. We independently verify this estimate using dynamic light scattering of a dilute 10ppm HPAM solution in the same index-matched solvent used in the flow experiments; we measure a mean hydrodynamic radius R h ranging from 40 to 320 nm, which corresponds to R g ≈ 160 to 210 nm using the shape factor  ≡ R g /R h ≈ 1.3 to 1.7 established previously (60).…”

Turbulent Drag Reduction with an Ultra-High-Molecular-Weight Water-Soluble Polymer in Slick-Water Hydrofracking

“…Thus, we used the conventional viscometry to determine the molecular weight. On the other hand, owing to the high viscosity and ionic groups, the common methods such as gel permeation chromatography and static light scattering are not appropriate for measuring the molecular weight of HVFR [28]. Thus, we used the conventional viscometry to determine the molecular weight.…”

“…1.0 M NaCl aqueous solution and five polymer aqueous solutions with different concentrations prepared by same solvent (1.0 M NaCl) were placed in an IVS400 automatic capillary viscometer (Zonwon Technology Co., Ltd., Hangzhou, China) with a capillary inner diameter of 0.55 mm at 30 • C. The running time of polymer solutions (t 1 ) and the solvent (t 0 ) was used to calculate the relative viscosity η r = t 1 /t 0 , and specific viscosity η sp = (t 1 − t 0 )/t 0 [28]. The intrinsic viscosity, [η], was obtained by extrapolating to infinite dilution and taking the intercept from Huggins and Kraemer diagrams.…”

Research Progress on Typical Quaternary Ammonium Salt Polymers

“…These other typical quaternary ammonium salt polymers frequently use the Mark-Houwink values from anionic polymers [13]. Otherwise, the K and α values of partially hydrolyzed polyacrylamide have also been studied [97]. They are summarized in Table 2.…”