Direct Thiol-Ene Photocoating of Polyorganosiloxane Microparticles

Titelangaben

Kuttner, Christian ; Maier, Petra C. ; Kunert, Carmen ; Schlaad, Helmut ; Fery, Andreas:
Direct Thiol-Ene Photocoating of Polyorganosiloxane Microparticles.
In: Langmuir. Bd. 29 (2013) Heft 52 . - S. 16119-16126.
ISSN 1520-5827
DOI: https://doi.org/10.1021/la4039864

Volltext

Link zum Volltext (externe URL):

Abstract

This work presents the modification of polyorga- nosiloxane microparticles by surface-initiated thiol−ene photochemistry. By this photocoating, we prepared different core/shell particles with a polymeric shell within narrow size distributions (PDI = 0.041−0.12). As core particle, we used highly monodisperse spherical polyorganosiloxane particles prepared from (3-mercaptopropyl)trimethoxysilane (MPTMS) with a radius of 0.49 μm. We utilize the high surface coverage of mercaptopropyl functions to generate surface-localized radicals upon irradiation with UVA-light without additional photoinitiator. The continuous generation of radicals was followed by a dye degradation experiment (UV/vis spectroscopy). Surface-localized radicals were used as copolymer anchoring sites ("grafting- onto" deposition of different PB-b-PS diblock copolymers) and polymerization initiators ("grafting-from" polymerization of PS). Photocoated particles were characterized for their morphology (SEM, TEM), size, and size distribution (DLS). For PS-coated particles, the polymer content (up to 24 in 24 h) was controlled by the polymerization time upon UVA exposure. The coating thickness was evaluated by thermogravimetric analysis (TGA) using a simple analytical core/shell model. Raman spectroscopy was applied to directly follow the time-dependent consumption of thiols by photoinitiation.