Abstract
The design of self-assembling materials in the nanometer scale focuses on the fabrication of a class of organic and inorganic subcomponents that can be reliably produced on a large scale and tailored according to their vast applications for, e.g. electronics, therapeutic vectors and diagnostic imaging agent carriers, or photonics. In a recent publication (Capone et al 2012 Phys. Rev. Lett. 109 238301), diblock copolymer stars have been shown to be a novel system, which is able to hierarchically self-assemble first into soft patchy particles and thereafter into more complex structures, such as the diamond and cubic crystal. The self-aggregating single star patchy behavior is preserved from extremely low up to high densities. Its main control parameters are related to the architecture of the building blocks, which are the number of arms (functionality) and the fraction of attractive end-monomers. By employing a variety of computational and theoretical tools, ranging from the microscopic to the mesoscopic, coarse-grained level in a systematic fashion, we investigate the crossover between the formation of microstructure versus macroscopic phase separation, as well as the formation of gels and networks in these systems. We finally show that telechelic star polymers can be used as building blocks for the fabrication of open crystal structures, such as the diamond or the simple-cubic lattice, taking advantage of the strong correlation between single-particle patchiness and lattice coordination at finite densities.
Highlights
The design of self-assembling materials in the nanometer scale focuses on the fabrication of a class of organic and inorganic subcomponents that can be reliably produced on a large scale and tailored according to their vast applications for, e.g. electronics, therapeutic vectors and diagnostic imaging agent carriers, or photonics
The quantity r denotes the separation between the centers of mass (CM) of the corresponding blobs, which are employed as the dynamical degrees of freedom in the coarse-grained simulation, replacing the underlying coordinates of the microscopic monomers
These effective interactions between blobs are determined by a first principles inversion procedure, that was derived for diblock copolymers [15, 16], generalizing the method used earlier for the simple dumbbell representation of the same [19,20,21]
Summary
The system we are considering, as well as the questions we aim to address, require a detailed knowledge of the phenomena that take place at both the microscopic and mesoscopic levels, and the best strategy is formed by computer simulations, employing various special techniques. The quantity r denotes the separation between the centers of mass (CM) of the corresponding blobs, which are employed as the dynamical degrees of freedom in the coarse-grained simulation, replacing the underlying coordinates of the microscopic monomers These effective interactions between blobs are determined by a first principles inversion procedure, that was derived for diblock copolymers [15, 16], generalizing the method used earlier for the simple dumbbell representation of the same [19,20,21]. In order to determine the intermolecular pair potentials, we consider the six possible combinations of αβ and γ δ dimers and calculate the corresponding blob–blob pair correlation functions hαγ (r ), as functions of the distance r between the CMs of the α-block of dimer 1 and the γ -block of dimer 2 This is achieved from MC-generated histograms, by averaging over allowed monomer configurations for fixed values of r , according to the usual Metropolis algorithm. This particular choice has been made in order to mimic as closely as possible a molecular dynamics simulation featuring the soft blobs as fundamental entities
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