Complex morphologies of self-assembled block copolymer micelles in binary solvent mixtures: the role of solvent–solvent correlations

Denkova, AG; Bomans, Phh Paul; Coppens, MO; Sommerdijk, Nico A. J. M.; Mendes, Eduardo

doi:10.1039/c1sm05461a

Cited by 44 publications

(49 citation statements)

References 42 publications

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“…Amorphous calcium carbonate with high levels of hydration behaved as a liquid in computer models (14). Furthermore, low image contrast in TEM was observed for a polymer-induced liquid precursor phase (31), as well as in tetrahydrofuran-water mixtures which underwent liquid-liquid phase separation (32). Importantly, the ion activity product derived from the titration curve at all times remained significantly below the solubility of ACC as reported by Brečevic and Nielsen (33) (see Fig.…”

Section: Resultsmentioning

confidence: 51%

A classical view on nonclassical nucleation

Smeets

Finney

Habraken

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

210

212

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Understanding and controlling nucleation is important for many crystallization applications. Calcium carbonate (CaCO 3 ) is often used as a model system to investigate nucleation mechanisms. Despite its great importance in geology, biology, and many industrial applications, CaCO 3 nucleation is still a topic of intense discussion, with new pathways for its growth from ions in solution proposed in recent years. These new pathways include the socalled nonclassical nucleation mechanism via the assembly of thermodynamically stable prenucleation clusters, as well as the formation of a dense liquid precursor phase via liquid-liquid phase separation. Here, we present results from a combined experimental and computational investigation on the precipitation of CaCO 3 in dilute aqueous solutions. We propose that a dense liquid phase (containing 4-7 H 2 O per CaCO 3 unit) forms in supersaturated solutions through the association of ions and ion pairs without significant participation of larger ion clusters. This liquid acts as the precursor for the formation of solid CaCO 3 in the form of vaterite, which grows via a net transfer of ions from solution according to z Ca 2+ + z CO 3 2− → z CaCO 3 . The results show that all steps in this process can be explained according to classical concepts of crystal nucleation and growth, and that long-standing physical concepts of nucleation can describe multistep, multiphase growth mechanisms.calcium carbonate | nucleation | crystal growth | cryo-electron microscopy | molecular simulation I n the process of forming a solid phase from a supersaturated solution, nucleation is the key step governing the timescale of the transition. Controlling nucleation is an essential aspect in many crystallization processes, where distinct crystal polymorphism, size, morphology, and other characteristics are required. It is, therefore, important to obtain a fundamental understanding of nucleation mechanisms.More than 150 years ago, a basic theoretical framework, classical nucleation theory (CNT) (1, 2), was developed to describe such nucleation events. CNT describes the formation of nuclei from the dynamic and stochastic association of monomeric units (e.g., ions, atoms, or molecules) that overcome a free-energy barrier at a critical nucleus size and grow out to a mature bulk phase. Calcium carbonate (CaCO 3 ) is a frequently used model system to study nucleation (3-5); however, despite the many years of effort, there are still phenomena associated with CaCO 3 crystal formation where the applicability of classical nucleation concepts have been questioned (6). These include certain microstructures and habits of biominerals formed by organisms (7), or geological mineral deposits with unusual mineralogical and textural patterns (8).Three anhydrous crystalline polymorphs of CaCO 3 are observed in nature: vaterite, aragonite, and calcite in order of increasing thermodynamic stability. In many cases, the precipitation of CaCO 3 from solution is described as a multistep process, with amorphous phases first pr...

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Section: Resultsmentioning

confidence: 51%

A classical view on nonclassical nucleation

Smeets

Finney

Habraken

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

210

212

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“…Such slow kinetics can lead to a coexistence of multiple metastable morphologies and/or the formation of different distinct morphologies that are kinetically stable (also known as kinetically trapped/locked phases) [266,267]. Formation of kinetically trapped structures is highly path-dependent (i.e., how the materials are being processed) and can be used judiciously to generate novel BCP-NP composite structures that would not be possible to obtain in normal equilibrium states [106].…”

Section: Processing Of Block Copolymer -Nanoparticle Compositesmentioning

confidence: 98%

Block copolymer–nanoparticle composites: Structure, functional properties, and processing

Sarkar

Alexandridis

2015

Progress in Polymer Science

215

159

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“…They found that bicontinuous micelles with distinct patterns formed at water contents between about 27 and 35 wt%, in coexistence with very long, non-branched, worm-like micelles. 25 In the study of Zhonget al, triblock copolymer horseshoe phase. 27 McKenzie et al showed that nanospheres with internal bicontinuous morphologies could be obtained from simple, amorphous diblock copolymer poly(ethylene oxide)-b-poly(n-butyl methacrylate) (PEO-b-PBMA) in a cosolvent of THF/water.…”

Section: Introductionmentioning

confidence: 99%

Morphological transformations of diblock copolymers in binary solvents: A simulation study

et al. 2017

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Morphological transformations of amphiphilic AB diblock copolymers in mixtures of a common solvent (S1) and a selective solvent (S2) for the B block are studied using the simulated annealing method. We focus on the morphological transformation depending on the fraction of the selective solvent C S2 , the concentration of the polymer C P , and the polymer-solvent interactions ε ij (i = A, B; j = S1, S2). Morphology diagrams are constructed as functions of C P , C S2 , and/or ε AS2 . The copolymer morphological sequence from dissolved → sphere → rod → ring/cage → vesicle is obtained upon increasing C S2 at a fixed C P . This morphology sequence is consistent with previous experimental observations. It is found that the selectivity of the selective solvent affects the self-assembled microstructure significantly. In particular, when the interaction ε BS2 is negative, aggregates of stacked lamellae dominate the diagram. The mechanisms of aggregate transformation and the formation of stacked lamellar aggregates are discussed by analyzing variations of the average contact numbers of the A or B monomers with monomers and with molecules of the two types of solvent, as well as the mean square end-to-end distances of chains. It is found that the basic morphological sequence of spheres to rods to vesicles and the stacked lamellar aggregates result from competition between the interfacial energy and the chain conformational entropy. Analysis of the vesicle structure reveals that the vesicle size increases with increasing C P or with decreasing C S2 , but remains almost unchanged with variations in ε AS2 .

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Complex morphologies of self-assembled block copolymer micelles in binary solvent mixtures: the role of solvent–solvent correlations

Cited by 44 publications

References 42 publications

A classical view on nonclassical nucleation

A classical view on nonclassical nucleation

Block copolymer–nanoparticle composites: Structure, functional properties, and processing

Morphological transformations of diblock copolymers in binary solvents: A simulation study

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