Application of asymmetric flow field-flow fractionation (AF4) and multiangle light scattering (MALS) for the evaluation of changes in the product molar mass during PVP-b-PAMPS synthesis

Abstract

The use of polymers for the delivery of drugs has increased dramatically in the last decade. To ensure the desired properties and functionality of such substances, adequate characterization in terms of the molar mass (M) and size is essential. The aim of this study was to evaluate the changes in the M and size of PVP-b-PAMPS when the amounts of the synthesis reactants in the two-step radical reaction were varied. The determination of the M and size distributions was performed by an asymmetric flow field-flow fractionation (AF4) system connected to multiangle light scattering (MALS) and differential refractive index (dRI) detectors. The results show that the M of the polymers varies depending on the relative amounts of the reactants and that AF4-MALS-dRI is a powerful characterization technique for analyzing polymers. Using AF4, it was possible to separate the product of the first radical reaction (PVP-CTA) into two populations. The first population had an elongated, rod-like or random coil conformation, and the second had a conformation corresponding to homogeneous spheres or a microgel structure. PVP-b-PAMPS had only one population, which had a rod-like conformation. The molar masses of PVP-CTA and PVP-b-PAMPS found in this study were higher than those reported in previous studies.

Insights into the internal structures of nanogels using a versatile asymmetric-flow field-flow fractionation method

“…AF4 also offers the opportunity to obtain information on the internal structure or the polymer architecture of a colloidal system. 21,22 This understanding of size and morphology of particles is extremely valuable. Of particular interest for obtaining insight into the internal structure of samples is the combination of DLS and MALS.…”

Recent Advances in Separation-Based Techniques for Synthetic Polymer Characterization

“…The study demonstrated that molar mass of the polymer aggregates decreased, and radius increased, as the pH value of the solution increased. Another emerging trend is the application of AF4-MALS for block copolymer characterization, such as for the evaluation of changes in the product molar mass during poly­( N -vinylpyrrolidone)- block -poly­(2-acrylamido-2-methyl-1-propanesulfonic acid) (PVP- b -PAMPS) synthesis . Additionally, amphiphilic copolymers can be difficult to characterize by SEC.…”

“…Another emerging trend is the application of AF4-MALS for block copolymer characterization, such as for the evaluation of changes in the product molar mass during poly(N-vinylpyrrolidone)-block-poly(2-acrylamido-2methyl-1-propanesulfonic acid) (PVP-b-PAMPS) synthesis. 64 Additionally, amphiphilic copolymers can be difficult to characterize by SEC. For example, adsorption of poly(vinyl alcohol) (PVA) on SEC columns was observed to be dependent on the degree of hydrolysis, but AF4 was successfully applied for molar mass characterization of PVA.…”

Matrix-dependent size modifications of iron oxide nanoparticles (Ferumoxytol) spiked into rat blood cells and plasma: Characterisation with TEM, AF4-UV-MALS-ICP-MS/MS and spICP-MS

“…The absence of a solid stationary phase enhances separation and reduces potential losses from analyte-column interactions. The AF4 fractionation system is equipped with a multi-angle light scattering (MALS) detector which has been applied for the accurate separation, particle size and molar mass characterization of polymers in drug delivery systems [26]. Multi-angle light scattering (MALS) detector generates a unique measurand for light scattering at various angles by individual particles of a macromolecule in solution known as the radius of gyration (R g ); defined as the root mean square distance of the object's mass from either its centre of mass or a given axis [27].…”