Synthesis of Amphiphilic Poly(organosiloxane) Nanospheres with Different Core−Shell Architectures

Abstract

Core-shell and core-shell-shell nanospheres with different amphiphilicities were synthesized by sequential condensation of trimethoxymethylsilane (T), diethoxydimethylsilane (D), and the functional monomer (chloromethylphenyl)trimethoxysilane (ClBz-T) and mixtures thereof. The condensation was performed in aqueous dispersion in the presence of surfactant. Saturation of reactive surface SiOH groups with monofunctional trimethylsilane monomers prevents interparticle condensation and leads to nanoparticles, which are redispersable in organic solvents. The diameters of the particles range between 20 and 40 nm, depending on the composition. The thickness of the outer, nonfunctionalized shell is determined by asymmetrical flow field-flow fractionation (AF-FFF) and dynamic light scattering (DLS) of the core and core-shell particles, respectively. It varies between 1.5 and 3 nm and is proportional to the volume of added monomer. Incorporating (chloromethylphenyl)siloxane groups in the core and performing a subsequent quaternization reaction of dimethylaminoethanol yield amphiphilic nanospheres with an ionic, hydrophilic core and a hydrophobic outer shell. The amount of ionic moieties is found to be proportional to the amount of functional (chloromethylphenyl)siloxane groups incorporated in the spheres. Additionally, multiple shell topologies were successfully prepared, i.e., particles with a poly(dimethylsiloxane) (PDMS) core, an ionic inner and a hydrophobic outer shell. If linear PDMS chains forming the core are prevented to chemically bind to the inner shell, they may be removed by ultrafiltration, resulting in the formation of hollow spheres.

Dye Loading of Amphiphilic Poly(organosiloxane) Nanoparticles

“…[b] n N = amount of quaternary ammonium ions in mmol per 10 mg of nanoparticle. [12] [c] n dye = amount of dye in mmol per 10 mg of nanoparticle. No data: nanoparticles partially precipitated at the interface.…”

“…The synthesis of amphiphilic nanoparticles is described in detail in reference [12] . The preparation is based on the hydrolysis and cocondensation of dialkoxydialkylsilane (D) and trialkoxyalkylsilane (T) in aqueous dispersion by sequential addition of monomer mixtures in the presence of a surfactant.…”

“…After surface modification they may be re-dispersed in organic solvents such as toluene. [12] Core-shell arrangements are formed through sequential monomer addition. Quaternary ammonium groups in the siloxane network provide the hydrophilic character of the core (QCx-S) or the inner shell (QC-Sx-S, QSx-S).…”

Bionanocomposites Assembled by “From Bottom to Top” Method

“…Besides, clays are ecologic and their antimicrobial properties are widely accepted in pharmaceutics, cosmetics, and food industry [252,253]. Layered silicates from smectite family [254][255][256][257][258] or fiber clays, such as sepiolites are used as inorganic reinforcing components in new materials like native bone and tissues [259]. The ways of formation of biohybrid materials based on layered silicates are similar to synthetic polymers and can be presented on the example of hemoglobin intercalation in organically modified magadiite (Fig.…”

Preparation of Functionalized Polysilsesquioxane and Polysilsesquioxane‐Metal Nanoparticle Composite Spheres

“…Polysilsesquioxanes (PSQ) are among the most promising materials for preparing spheres of narrow size distributions that contain functional groups. PSQ are especially interesting because many alkyltrialkoxysilane (ATAS) can be easily polymerized into spherical shapes [1][2][3][4][5][6] and different functionalized ATAS are easily available. PSQ also exhibit a variety of technologically important properties, with applications in coatings, optics, fabrication of fiber materials for photoconductors, and chromatography.…”