Amphiphilic Linear PEO−Dendritic Carbosilane Block Copolymers

Abstract

A new class of amphiphilic linear-dendritic diblock copolymers based on hydrophilic linear PEO and hydrophobic dendritic carbosilane were synthesized using a divergent approach at the allyl end group of the allyl-terminated PEO. The amphiphilic nature of these block copolymers was highly dependent on the size of the hydrophobic dendritic block. The block copolymer with the dendritic moiety of a third generation could not be dispersed in water. The block copolymers with the first (PEO-Si-1G) and, the second (PEO-Si-2G) generation of dendritic carbosilane blocks form micelles in an aqueous phase. The critical micelle concentrations of PEO-Si-1G and PEO-Si-2G, determined by a fluorescence technique, were 82.6 and 2.3 mg/L, respectively. The mean diameters of the micelles of PEO-Si-1G and PEO-Si-2G, measured by dynamic light scattering, were 120 and 170 nm. The partition equilibrium constants, Kv, of pyrene in the micellar solution increased by increasing the size of the dendritic block, e.g., 9.13 × 10 3 for PEO-Si-1G and 1.75 × 10 5 for PEO-Si-2G. The steady-state fluorescence anisotropy values (r) of 1,6diphenyl-1,3,5-hexatriene (DPH) were 0.08 for PEO-Si-1G and 0.10 for PEO-Si-2G. The r values were lower than the linear polymeric amphiphiles, suggesting that the microviscosity of the dendritic micellar core is lower than those of other polymeric micelles.

Temperature sensitivity and drug encapsulation of star‐shaped amphiphilic block copolymer based on dendritic poly(ether‐amide)

“…Both are much lower than that of low molecular weight surfactants, for example, 2.3 g/L for sodium dodecyl sulfate (SDS), and also quite lower than that of other dendritic micelles. 2,33 This indicates that the synthesized star-shaped block copolymers in this study possess strong thermodynamic stability in the aqueous solutions and can perform as favorable hydrophobic drug carriers.…”

Interfacial properties of amphiphilic dendritic polymers

“…57 A similar approach also served to synthesize diblock and triblock copolymers by growing carbosilane dendrons from allyl-terminated PEO chains. 58,59 The major distinction between amphiphilic dendritic-linear hybrids and other amphiphilic dendritic molecules is that most hybrids behave like surfactants and block copolymers, forming micelles by aggregation once a minimum concentration (CMC) is attained.…”

Effect of the Branching Pattern of Hydrophobic Dendrons on the Core Structure of Linear‐Dendritic Copolymer Micelles

“…Therefore, tuning the macromolecular architecture to study its effect on the morphology and aggregation behavior is an important theme in this area. [ 1 ] Amphiphilic copolymers of various architectures such as linear, cyclic, brush, and dendritic have attracted great interest recently due to their promise of novel and controlled morphologies in solution that can be tuned in terms of hydrophobic dendron with hydrophilic linear chain [9][10][11] or by connecting hydrophilic dendron to hydrophobic linear chain. [12][13][14] Typically, the micellar behavior and the morphology of such linear-dendritic copolymers have been studied with reference to dendron generation.…”