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Abstract Over the past three decades, studies have indicated a mobile surface layer with steep gradients on glass surfaces. Among various glasses, polymers are unique because intramolecular interactions — combined with chain connectivity — can alter surface dynamics, but their fundamental role has remained elusive. By devising polymer surfaces occupied by chain loops of various penetration depths, combined with surface dissipation experiments and Monte Carlo simulations, we demonstrate that the intramolecular dynamic coupling along surface chains causes the sluggish bulk polymers to suppress the fast surface dynamics. Such effect leads to that accelerated segmental relaxation on polymer glass surfaces markedly slows when the surface polymers extend chain loops deeper into the film interior. The surface mobility suppression due to the intramolecular coupling reduces the magnitude of the reduction in glass transition temperature commonly observed in thin films, enabling new opportunities for tailoring polymer properties at interfaces and under confinement and producing glasses with enhanced thermal stability. 

Cannabidiol (CBD) is viewed as a promising therapeutic agent against a variety of health ailments; however, its efficacy is limited by poor aqueous solubility. Amorphous solid dispersions (ASDs) can enhance the solubility of therapeutics by distributing them throughout a polymer matrix. In consideration of ASD formulations with CBD, we investigate the interactions of CBD with various polymers: poly(vinylpyrrolidone) (PVP), poly(vinylpyrrolidone)/vinyl acetate (PVP/VA) copolymer, hydroxypropyl methylcellulose phthalate (HPMCP), hydroxypropyl methylcellulose acetate succinate (HPMCAS), and poly(methyl methacrylate) (PMMA). Both the experiment and molecular dynamics simulation reveal diverse mixing behavior among the set of polymers. Detailed structural and nanoscale interaction analyses suggest that positive deviations from ideal mixing behavior arise from the formation of stable polymer–CBD hydrogen bonds, whereas negative deviations are associated with disruptions to the polymer–polymer hydrogen bond network. Polymer–water interaction analyses indicate the significance of polymer hydrophobicity that can lead to poor dissolution of CBD. These results have implications for drug dissolution rates based on how CBD and water interact with each polymer. Furthermore, these insights may be used to guide ASD formulations for CBD or other small-molecule therapeutic agents. 

Matrix-assisted pulsed laser evaporation enables precise control of polymer film deposition, facilitating the creation of well-oriented epitaxial polymer films and offering insights into confined crystallization. 

In addition to the repulsive and attractive interaction forces described by Derjaguin–Landau–Verwey–Overbeek (DLVO) theory, many charged colloid systems are stabilized by non-DLVO contributions stemming from specific material attributes. Here, we investigate non-DLVO contributions to the stability of polymer colloids stemming from the intra-particle glass transition temperature ( T g ). Flash nanoprecipitation is used to fabricate nanoparticles (NPs) from a library of polymers and dispersion stability is studied in the presence of both hydrophilic and hydrophobic salts. When adding KCl, stability undergoes a discontinuous decrease as T g increases above room temperature, indicating greater stability of rubbery NPs over glassy NPs. Glassy NPs are also found to interact strongly with hydrophobic phosphonium cations (PR 4 + ), yielding charge inversion and intermediate aggregation while rubbery NPs resist ion adsorption. Differences in the lifetime of ionic structuration within mobile surface layers is presented as a potential mechanism underlying the observed phenomenon.