Density Functional Study for Homodendrimers and Amphiphilic Dendrimers

Abstract

The conformation of homodendrimers and amphiphilic dendrimers in various solvents is studied using classical density functional theory (DFT), in which the excluded-volume effects are treated explicitly. For homodendrimers in an athermal solvent, DFT results predict a remarkable fold-back behavior for the outer generation of segments, supporting the dense-core model. A coil-to-globule transition is observed for homodendrimers in a poor solvent. The size of the dendrimers, characterized by the radius of gyration, ⟨Rg⟩, is found to follow the scaling relationship, ⟨Rg⟩ ∼ N(ν), where N is the total number of segments of the dendrimers. For amphiphilic dendrimers, DFT results show that chemical modification in the outermost generation is an effective method to drive the ends toward the periphery of the dendrimers. In particular, a conformation with a hollow interior structure could be formed for amphiphilic dendrimers with longer end spacers in a selective solvent. The resulting unimolecular micelles with a hollow core and dense shell could serve as a unique candidate for encapsulation applications, such as sustained-drug-release nanocontainers.

Density functional study of dendrimer molecules in solvents of varying quality

“…Since there is always ambiguity and controversy over the definition of solvent quality and collapse, plus the differences in the details of the study methods, no definitive conclusions have been drawn in this regard. Recently, Chen et al 31 applied classical density functional theory (DFT) to study the conformation of homodendrimers and amphiphilic dendrimers in various solvents and found the existence of dense-core and dense-shell structures under different conditions.…”

Formation of a Hollow Core in Dendrimers in Solvents

“…The formation of hollow core inside copolymer dendrimer molecule is poorly investigated to date. Two reports [ 92,94 ] predicting the existence of hollow core conformation of dendrimer are available. Two different theoretical methods have been used in these studies S cheutjens– F leer s elf‐ c onsistent f ield approach—SF‐SCF [ 171 ] in Ref.…”

“…[ 87–90 ] One of the most straightforward ways to form a hollow core inside a dendrimer is to use terminal groups which pervasion to the inner volume of the molecule is limited, for instance, due to steric reasons (too large volume of terminal groups [ 91 ] or low compatibility with other segments of dendrimer). Both, theory [ 92–95 ] and experimental studies [ 96,97 ] presented in Section 3 of this review suggest a realistic example of hollow core formation in codendrimer with different terminal and inner segments which can be experimentally detected using NMR. At the end of this review, the main results are comprised in Summary.…”

Polymer Brushes Immersed in Two-Component Solvents with Pure Volume Exclusion: Effect of Solvent Molecular Shape

“…We employ the classical DFT approach. 31,41,42 The volume exclusion is the only interaction in our model.…”