Structural Insights into Polymethacrylamide-Based LCST Polymers in Solution: A Small-Angle Neutron Scattering Study

Abstract

Copolymerization is a powerful method that offers access to new polymer materials with a tailored response to external stimuli like temperature and pH. Polymers with a lower critical solution temperature are well known to undergo a coil-toglobule transition when the temperature is raised above the transition temperature. In particular, for copolymers, complex inter-and intrachain interactions may complicate this simple picture of a single-chain phase transition. In this work, we study the phase transition of poly((methylacrylamide)-stat-(N-cyclohexylacrylamide)) copolymers at different concentrations in heavy water by using small-angle neutron scattering. Measurements are performed well below and above the respective cloud points of polymers with two different molecular weights. We show that interchain interactions are already present below the cloud point even in the dilute regime. Above the cloud point, polymer−polymer interactions become more prominent and polydisperse aggregates form.

A dual responsive ionic liquid-based polymeric hydrogel: a promising drug delivery vehicle for the treatment of breast cancer

“…The fitting was performed using SASFit analysis software utilising Gaussian coil-like and worm-like micelles fitting models. 32,33…”

Sodium dodecyl sulfate modulates the structure and rheological properties of Pluronic F108–poly(acrylic acid) coacervates)

“…These 1D SAXS profiles were fit to the correlation length model developed by Hammouda 74 that has been shown to describe the scattering of polymer solutions with associations and covalently crosslinked hydrogels. 75,76 This model uses a power law to describe fluctuations at length scales greater than the measured q range and a Lorentzian function to describe the scattering from chains in solution as:…”

“…For network polymers, this xL term is typically associated with the mesh size. 75,76 At low [SDS]sol, there is a clear correlation peak in the scattering that is attributed to the self-assembly of the Pluronic within the coacervate. These micelles act as large associating centers for the coacervates.…”

Molecular Dynamics Calculations for the Temperature Response of Poly(alkylated tri(ethylene oxide)isocyanate) Aqueous Solution

“…Therefore, a coil-globule structural transition is considered a necessary driving force for LCST-type phase transitions to occur. Experimentally, the coil-globule transition at the LCST has been observed by fluorescence measurements [5][6][7], dynamic light scattering (DLS) measurements [8][9][10], small-angle X-ray scattering [11], and small-angle neutron scattering [12]. Molecular dynamics (MD) can be used to explain the correlation between the phase transition and coil-globule transition.…”