Structural Organisation of Oligohydroxyethylaminoethylurethane Dendrimers

This study investigates the structural and colloidal properties of oligohydroxyethylaminoethyl urethane dendrimers from the first to the fourth generations (G1-G4). All generations demonstrate an amorphous phase state, confirmed by X-ray structural analysis, with a characteristic broad peak at 2θ = 10-30°. Molecular modelling (PM3 method) reveals the evolution of the structure with increasing generation: the sizes of dendrimers increase from 1.45×0. 76 nm (G1) to 4.12×2.71 nm (G4), while the aspect ratio decreases (1.91 → 1.52), indicating the progressive formation of a spherical architecture. The growth of dendrimer generations reflects hierarchical tree-like self-organisation. Dynamic light scattering (DLS) demonstrates the dependence of hydrodynamic diameters on concentration: G1: 977 → 137 nm (1×10⁻³ → 1×10⁻⁶ mol·l⁻¹), G2: 1621 → 119 nm, and G3: 598 → 105 nm. Dendrimer G4 (~360 nm) exhibits unique resistance to aggregation. Analysis of dendrimers using scanning electron microscopy (SEM) confirms the presence of monodisperse spherical particles (90-120 nm) in G1, G3 and G4, while larger aggregates (150-200 nm) are observed in G2. It is noteworthy that the discrepancy between the DLS and SEM results for G4 (360 nm vs. 90-120 nm) is likely due to the influence of G4 hydration in DLS and drying artifacts in SEM. The aggregates remain stable after drying (90-200 nm), which is extremely important for applications such as drug delivery, catalysis, and the creation of functional materials. The results obtained allow the development of dendritic systems with programmable properties for nanotechnology and biomedicine.