(F-225) Parameter Estimation of the Mark-Houwink-Sakurada Equation for the Characterization of the Molecular Weight of PEG/PEO-Based Polymers

Introduction:: Molecular weight (M) characterization plays a fundamental role in understanding the structure and properties of macromolecules in various scientific and industrial fields. Viscometry, a well-established technique, offers a powerful tool for determining the molecular weight of polymers and biomolecules. Compared to other techniques like gel permeation chromatography and light scattering, viscometric analysis is the most cost-efficient technique that can be easily adopted in most laboratories. This study utilizes the polymer-solvent relationship of the Mark-Houwink-Sakurada (MHS) equation, n = KM, to correlate the molecular weight of poly(ethylene glycol)/poly(ethylene oxide) (PEG/PEO) and the inherent/reduced viscosity of aqueous-based polymer solutions as it relates to the polymer’s intrinsic viscosity, n. PEG and PEO are polymers extensively utilized for drug delivery and biomedical applications, but the characterization of viscosity of aqueous solutions has not been carefully characterized or reported in current literature. To calculate the parameters K and ɑ, seven polymers Ms with estimated values of 3.4, 6.0, 10.0, 20.0, 150.0, 250.0, and 325.0 kDa were used at nine different concentrations. Using the intercept of the curve between the inherent/reduced viscosity and the polymer concentration for each M the intrinsic viscosity was estimated. Using the linearized form of the Mark-Houwink-Sakurada equation, the parameters K and ɑ were estimated for PEG/PEO. Our current results will facilitate the estimation of the M of unknown PEG/PEO mixtures by measuring the viscosity of aqueous-based solutions.


Materials and Methods:: https://docs.google.com/presentation/d/1gEuiT4k1pfNkNLKcmchdJPbcmUHxSpmu/edit?usp=drivesdk&ouid=111216799474859154869&rtpof=true&sd=true

Through a process on the desired polymers to be characterized, solutions ranging from four to twelve percent concentrations of the desired polymer were produced within a deionized water solvent, and a five percent salt solution solvent. Upon creating the multiple solutions, The use of an AMETEK Brookfield Viscometer gathered the intrinsic viscosity of each polymer corresponding to its respective concentration/solvent. The MHS equation relates the intrinsic viscosity ([η]) of a polymer to its molecular weight (M) and a set of constants (K and α) that depend on the polymer-solvent system. Upon gathering the intrinsic viscosities, the graph of the polymer’s reduced/inherent viscosity as they relate to the concentrations was obtained to better characterize the values of the constants. The obtained calibration constants were then applied to calculate the molecular weight of the PEG/PEO samples under investigation.


Results, Conclusions, and Discussions:: https://docs.google.com/presentation/d/1gEuiT4k1pfNkNLKcmchdJPbcmUHxSpmu/edit?usp=drivesdk&ouid=111216799474859154869&rtpof=true&sd=true

The parameters K and 𝛼 in the Mark-Houwink-Sakurada equation are function of the ionic strength of the solvent solution.











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