Sequence of Polyurethane Ionomers Determinative for Core Structure of Surfactant–Copolymer Complexes

Abstract

The core of micelles self-assembled from amphiphiles is hydrophobic and contains little water, whereas complex coacervate core micelles co-assembled from oppositely charged hydrophilic polymers have a hydrophilic core with a high water content. Co-assembly of ionic surfactants with ionic-neutral copolymers yields surfactant–copolymer complexes known to be capable of solubilizing both hydrophilic and hydrophobic cargo within the mixed core composed of a coacervate phase with polyelectrolyte-decorated surfactant micelles. Here we formed such complexes from asymmetric (PUI-A2) and symmetric (PUI-S2), sequence-controlled polyurethane ionomers and poly(N-methyl-2-vinylpyridinium iodide)29-b-poly(ethylene oxide)204 copolymers. The complexes with PUI-S2 were 1.3-fold larger in mass and 1.8-fold larger in radius of gyration than the PUI-A2 complexes. Small-angle X-ray scattering revealed differences in the packing of the similarly sized PUI micelles within the core of the complexes. The PUI-A2 micelles were arranged in a more ordered fashion and were spaced further apart from each other (10 nm vs. 6 nm) than the PUI-S2 micelles. Hence, this work shows that the monomer sequence of amphiphiles can be varied to alter the internal structure of surfactant–copolymer complexes. Since the structure of the micellar core may affect both the cargo loading and release, our findings suggest that these properties may be tuned through control of the monomer sequence of the micellar constituents.

The Physical Chemistry and Chemical Physics (PCCP) Section of the International Journal of Molecular Sciences in Its Publications: The First 300 Thematic Articles in the First 3 Years

“…Much less space is occupied by the works related to polymeric (in fact, to a high molecular weight) compounds [ 113 , 114 , 134 , 149 , 152 , 160 , 173 , 177 , 179 , 181 , 182 ]; moreover, they are all, in one way or another, related to the study of proteins (polypeptides). There are practically no works on the structure/dynamics of synthetic polymers in the list of these 300 publications; the only exception, and even then with a stretch, that can be considered is article [ 177 ], in which polyurethane fibers are one of the objects of research. In fact, in this list, there are no articles in which the object of study would be ions, free radicals, and clusters, although, with a certain stretch, they can be attributed to them [ 118 , 155 , 169 ], in particular, publication [ 118 ] devoted to the N,N–di(4–Bromo)nitrenium.…”