Molecular Dynamics Simulations of Linear and Cyclic Amphiphilic Polymers in Aqueous and Organic Environments

Abstract

We have studied the conformational changes of two novel amphiphilic homopolymers in water and toluene relevant to delivery applications using molecular dynamics simulations supplemented with enhanced sampling techniques. The individual homopolymer repeating units are amphiphilic with a hydrophobic dodecyl chain and a hydrophilic tetra(ethylene glycol) chain attached via ether linkages to each repeating unit of the polymer backbone. Two polymer topologies were examined: one cyclic and one an exact linear analog. Here we show that these polymers exhibit highly dynamic conformations with the side arm orientations driven by the solvent polarity. In water these polymers exhibit a compact conformation with the hydrophobic arms retracted toward the backbone core, whereas in toluene the hydrophobic arms extended into the solvent. Different from the hydrophobic arms, the hydrophilic ethylene glycol chain orientations and backbone conformations are largely unperturbed by the solvent polarity. Probing the polymer microenvironment in different solvents to examine solute uptake supports the hypothesis that these polymers can selectively encapsulate/release guest molecules depending on the solvent polarity, highlighting the potential of these polymers as drug delivery vehicles.

Polarity of Cationic Lignin Polymers: Physicochemical Behavior in Aqueous Solutions and Suspensions

“…The charge density of the insoluble part of CHLs was also measured by the PCD instrument following the back titration method according to previously established work. Finally, the overall charge densities of CHLs considering the soluble and insoluble charge densities of CHLs were reported herein …”

“…Finally, the overall charge densities of CHLs considering the soluble and insoluble charge densities of CHLs were reported herein. [77] The phenolic hydroxy group of CHLs was measured using an automatic potentiometric titrator, 785 Titrino. In this analysis, 0.06 g of CHLs was dissolved in 1 mL of KOH (0.8 M) and then 4 mL of para hydroxybenzoic acid (0.5 wt %) was added to the system as an internal standard.…”

ATRP Synthesis of Sunflower Polymers Using Cyclic Multimacroinitiators

“…Polymer nanostructures with advanced architectures (e.g. cyclic polymers, 1-3 polymer brushes, 4,5 star polymers, 6,7 and hyperbranched polymers) 8,9 are a promising class of materials for this application. 10 Indeed, Szoka and coworkers have demonstrated that cyclic polymers and PEG-grafted cyclic polymers exhibit longer circulation times than their analogous, molecular weight-matched linear polymers.…”

Analyzing PEGylation through Molecular Dynamics Simulations

“…Starovoytov et al, developed a quantum chemistry‐based polarizable potential for PEO in aqueous solution (PFF‐4) that provided a description of PEO‐water and DMP‐water solutions consistent with experimental observations . Several groups studied the conformation and dynamics properties of PEG in water and other organic solvents such as methanol, chloroform, carbon tetra‐ chloride, and n‐heptane …”