Polyisobutylene-block-poly(methacrylic acid) Diblock Copolymers:  Self-Assembly in Aqueous Media

Abstract

Ionic amphiphilic diblock copolymer polyisobutylene-block-poly(methacrylic acid) (PIBx-b-PMAAy), with various lengths of nonpolar (x=25-75) and polyelectrolyte (y=170-2600) blocks, spontaneously dissolve in aqueous media at pH>4, generating macromolecular assemblies, the aggregation number of which depends on external stimuli (pH and ionic strength). Spherical micellar morphology with a compact core formed by the PIB blocks and a swollen corona built up from the PMAA blocks was deduced by cryogenic transmission electron microscopy. The micelles were further characterized by means of dynamic and static light scattering as well as small-angle neutron scattering. The critical micellization concentration, estimated by means of fluorescence spectroscopy with the use of pyrene as a polarity probe, is decisively determined by the length of the PIB block and is insensitive to changes in the length of the PMAA block.

Interpolyelectrolyte Complexes Based on Polyionic Species of Branched Topology

“…Detailed analysis of the scattering curves obtained by SANS (Fig. 14) strongly suggest that the aggregation number of the original PIB-b-PMANa micelles hardly changes upon their interaction with P4VPQ [67][68][69], i.e., upon formation of the complex particles, although the original micelles exhibit "dynamic" properties [94]. Apparently, interpolyelectrolyte complexation of such micelles with oppositely charged linear PE does not make them "frozen" structures as their aggregation numbers remain sensitive to variations in the pH of the surrounding solution [69].…”

Tandem mass spectrometry of poly(methacrylic acid) oligomers produced by negative mode electrospray ionization

“…where C 8 2 is the total number of possibilities to arrange 2 charged monomers in a series of 8 and C 5 2 the number of these arrangements which allow neutral monomer pairs to exist. In a doubly deprotonated 9-mer, this probability increases to…”

“…Hydrogels, i.e., weakly cross-linked hydrophilic polymers, obtained after copolymerization of polyethylene glycol (PEG) with methacrylic acid were recently demonstrated to be efficient absorbents of uranyl ions [2]. On the other hand, the ability of amphiphilic PMAA-based block copolymers to self-assemble and produce dynamic micelles sensitive to different stimuli was shown to highly depend on the balance between hydrophobic and hydrophilic segments [3][4][5][6]. Since the performance of such copolymer materials is closely associated to structurally related parameters, unambiguous characterization of their microstructure is a crucial analytical issue.…”

Effective short-range Coulomb correction to model the aggregation behavior of ionic surfactants

“…The structural features of these clusters, such as size, shape and packing, are deeply related to some key physico-chemical parameters (temperature, pH, salt concentration, etc.) [1][2][3][4][5][6][7][8] as well as to the molecular architecture of their building blocks [9]. Their spontaneous aggregation or self-assembly, being rather recurrent in soft matter systems, is driven by a complex competition between enthalpic and entropic forces, which might be dramatically altered by almost intangible thermal fluctuations of few k B T , with T the absolute temperature and k B 1.38 × 10 −23 J K −1 the Boltzmann's constant.…”