Diblock self-assembly behavior

A pH dependent self-assembly behavior was also observed for PNHOS-PEO diblock copolymers [12]. The presence of basic and acidic groups on the same segment of the PNHOS block allows for variation of the solubility and the internal structure of the aggregates formed at different pH values, as it was confirmed by dynamic light scattering and fluorescence spectroscopy. 

Synthesis and self-assembly behavior of amphiphilic diblock copolymer dextran-block-poly(e-caprokictone) (DEX-b-PCL) in aqueous media. eXPRESS Polym. Lett., 4, 599. 

Weaver, J.V.M., Liu, S. and Armes, S.P. (2003) Holy trinity of micelles in aqueous solution at ambient temperature unprecedented self-assembly behavior from a binary mixture of a neutral-cationic diblock copolymer and an anionic polyelectrolyte. ACS Polym. Prepr. (Div. Polym. Chem.), 44(1), 651-652. 

Taton and Lecommandoux reported the self-assembly behavior of AB diblock copolymers and miktoarm AB2 star polymers comprised of PS (=A) and poly(glutamic acid) (=B) segments (Babin et al, 2005). AFM image and X-ray scattering data indicated that those polymers displayed hexagonally packed cylinders of helical rods within lamellar phase. 

Hsu C-H et al. Self-assembly behavior of A-B diblock and C-D random copolymer mixtures in the solution state through mediated hydrogen bonding. Langmuir 2008 24(15) 7727-7734. 

Minich E.A., Nowak A.P., Deming T.J., and Pochan, D.J. Rod-rod and rod-coil self-assembly and phase behavior of pol3fpeptide diblock copolymers. Polymer, 45, 1951, 2004. 

In the simplest case of linear AB diblock and ABA triblock copolymers, the phase behavior has been the subject of numerous theoretical and experimental studies over recent decades and is relatively well understood [89-96]. As mentioned before, the self-assembly process is driven by an unfavorable mixing enthalpy and small mixing entropy, while the covalent bond connecting the blocks prevents... 

Summary PDMS-6-PEO short-chain diblock copolymers were prepared via anionic ring-opening polymerization of cyclosiloxanes. Applying this method, various well-defined block copolymers with different compositions were synthesized and their phase behavior was investigated. The polymers predominantly showed lamellar phases in aqueous solutions. At small surfactant concentrations, vesicles were formed, as observed via cryogenic TEM. The aggregates of the diblock copolymers were used for the formation of lamellar thin films, applying the evaporation-induced self-assembly approach. 

PFS block co-polymers in which the blocks are immiscible (which is generally the case) would be expected to self-assemble to form phase-separated organometallic domains in the solid state. Based on the classical behavior of organic block co-polymers, thin films of polyferrocene diblock co-polymers would be expected to form domains such as spheres, cylinders (or their anti-structures), double diamonds (or gyroids), or lamellae (Section 1.2.5). The preferred domain structure would be expected to be controlled by the ratio of the blocks, their degree of immiscibility (as defined by the Flory-Huggins interaction parameter y), and the overall molecular weight of the block co-polymer. 

A number of theoretical studies have been devoted to analysis of the self-assembly of amphiphilic ionic/hydrophobic diblock copolymers [13-24]. Most of these studies considered copolymers with strongly dissociating (also referred to as quenched ) PE blocks [13-18, 20] and extensively exploited the analogy between the conformation of PE blocks in a corona and that in a spherical PE brush [25-33] or PE stars (see [10] for a review). The micellization and the responsive behavior of nanostructures formed by copolymers with pH-sensitive PE blocks have also been systematically studied in recent years [19, 21-23]. 

We start with a brief reminder of the theory of self-assembly in a selective solvent of non-ionic amphiphilic diblock copolymers. Here, the focus is on polymorphism of the emerging copolymer nanoaggregates as a function of the intramolecular hy-drophilic/hydrophobic balance. We then proceed with a discussion of the structure of micelles formed by block copolymers with strongly dissociating PE blocks in salt-free and salt-added solutions. Subsequently, we analyze the responsive behavior of nanoaggregates formed by copolymers with pH-sensitive PE blocks. The predictions of the analytical models are systematically complemented by the results of a molecularly detailed self-consistent field (SCF) theory. Finally, the theoretical predictions are compared to the experimental data that exist to date. 

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