Polydispersity-Driven Block Copolymer Amphiphile Self-Assembly into Prolate-Spheroid Micelles

The aqueous self-assembly behavior of polydisperse poly­(ethylene oxide-<i>b</i>-1,4-butadiene-<i>b</i>-ethylene oxide) (OBO) macromolecular triblock amphiphiles is examined to discern the implications of continuous polydispersity in the hydrophobic block on the resulting aqueous micellar morphologies of otherwise monodisperse polymer surfactants. The chain length polydispersity and implicit composition polydispersity of these samples furnishes a distribution of preferred interfacial curvatures, resulting in dilute aqueous block copolymer dispersions exhibiting coexisting spherical and rod-like micelles with vesicles in a single sample with a O weight fraction, <i>w</i>_O, of 0.18. At higher <i>w</i>_O = 0.51–0.68, the peak in the interfacial curvature distribution shifts and we observe the formation of only American football-shaped micelles. We rationalize the formation of these anisotropically shaped aggregates based on the intrinsic distribution of preferred curvatures adopted by the polydisperse copolymer amphiphiles and on the relief of core block chain stretching by chain-length-dependent intramicellar segregation

Poly(vinyl acetate-<i>b</i>-vinyl alcohol) Surfactants Derived from Poly(vinyl ester) Block Copolymers

Poly(vinyl acetate-b-vinyl alcohol) Surfactants Derived from Poly(vinyl ester) Block Copolymer

Potential Artifacts in Sample Preparation Methods Used for Imaging Amyloid Oligomers and Protofibrils due to Surface-Mediated Fibril Formation

Accurate imaging of nanometer-sized structures and morphologies is essential to characterizing amyloid species formed at various stages of amyloid aggregation. In this article, we examine the effect of different drying procedures on the final morphology of surface-mediated fibrils formed during the incubation period, which may then be mistaken as oligomers or protofibrils intentionally formed in solution for a particular study. Atomic force microscopy results show that some artifacts, such as globules, flakelike structures, and even micrometer-long fibrils, can be produced under various drying conditions. We also demonstrate that one can prevent drying artifacts by using an appropriate spin-coating procedure to dry amyloid samples. This procedure can bypass the wetting/dewetting transition of the liquid layer during the drying process and preserve the structure of interest on the substrate without generating drying artifacts