Intrinsic viscosity is “a measure of a solute’s contribution to the viscosity of a solution”. Intrinsic viscosity is a common characterization tool for synthetic polymers in organic solvents because it provides information about the individual macromolecules in your solution. When complementary data is available, the analysis can also provide an estimation for the hydrodynamic radius or molecular weight.
The intrinsic viscosity coefficient quantifies the viscosity enhancement due to the presence of macromolecules in solution independent of pair interactions. In other words, it reflects the characteristics of individual macromolecules in a particular solvent. Molecular weight, solvent quality, and molecular structure (i.e. linear versus branched) will all influence the space or volume occupied by the macromolecules and therefore intrinsic viscosity. As a result, it is common to use the intrinsic viscosity analysis as a means of molecular weight determination once a correlation has been established for a particular polymer-solvent combination.
Typical measurement methods are manual and/or use large sample volumes making the intrinsic analysis inconvenient. The intrinsic viscosity protocol involves measurement of a concentration series in the dilute regime. The analysis is simplified in the dilute limit since viscosity can be expressed as a Taylor series expansion in concentration.
Last August, RheoSense released the new VROC® initium one plus, the leading automatic viscometer that measures viscosity with the highest accuracy (2% of reading) and repeatability (0.5% of reading). With the introduction of the VROC® initium one plus, automated viscosity measurements are now possible for formulations prepared in organic solvents as well as aqueous, allowing the initium one plus to replace the manual/large sample volume methods for aqueous and organic systems. The automated system facilitates dilute solution viscosity measurements and therefore the intrinsic viscosity analysis.
Want to learn more about measuring the intrinsic viscosity of synthetic polymers in organic solvents?
Want to learn more about how the VROC initium one plus is revolutionizing viscosity characterization of Newtonian and non-Newtonian samples? Check out our product page or contact us to learn more!
Written by: Stacey Elliott, PhD, RheoSense Principal Scientist