Organophosphorus coupling agents bearing permanently charged functional groups (either cationic quaternary ammonium or anionic sulfonates) were synthesized and used for the modification of zirconia nanoparticles with a diameter <10 nm. Surface functionalization was confirmed by FTIR and solid-state NMR spectroscopy. Surface coverages up to 2.3−2.4 molecules/nm 2 were achieved for modification with these charged coupling agents. The pH-dependent charge measurements of homogeneously modified particles showed stable surface charges over a wide range of pH for both ammonium-and sulfonate-functionalized particles. Surface charge measurements of particles cofunctionalized with charged coupling molecules and uncharged methyl phosphonic acid revealed a decreasing charge density with increasing amount of uncharged coupling agent. Thus, an adjustment of charges by co-functionalization was obtained on the particle surface. The thus-formed surface-charged colloids were used in a second step for electrostatic-driven aggregation phenomena necessary for layer-by-layer processes. Sulfonate-modified negatively charged SiO 2 submicrometer particles of 506 nm in diameter were decorated with ammonium-modified ZrO 2 nanoparticles. In addition, a layer-by-layer deposition of alternating charge-modified TiO 2 nanoparticles was proven by optical spectroscopy. Due to the broad applicability of organophosphorus coupling agents for surface modification, particularly for transition-metal oxides, the shown route represents a general method for the creation of almost pH-independent charges on the surface of nanoparticles.
To abolish the bad reputation of synthetic polymer chemistry, we aimed to produce green polymers in an environmentally friendly way. It is also essential to bypass the application of components from fossil resources; those are not only polluting but also expensive ones. As an addition, we want to form engineered polymers with predetermined chain lengths and copolymerization possibilities. In this paper, we polymerized a terpene using UV triggered reversible‐deactivation radical polymerization, in bulk. No use of components from fossil resources, no high energy nor any solvent consumption; all these together show the right way towards green polymers.
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