Dendritic‐Linear Hybrid Multiarm Star Polymers: A Straightforward Synthesis of Polymer as Molecular Nanoparticles

Abstract

Synthesis of multiarm star polymers via “core first” method but possibly through two different chain growth fashions has been described. Two distinct styrenyl‐TEMPO‐based G3 and G4 dendritic unimolecular initiators have been used for this method. Polymerization of styrene using these core‐cum‐initiators at 125 °C varying the monomer to initiator ratio and polymerization time yields multiarm star polymers with molecular weight (Mw) in the range of 1.71 × 105 to 4.75 × 105 g mol−1 and polydispersity in the range of 1.34–1.46. Hydrolysis leading to degradation of inner polyurethane core yields highly narrow dispersed—PDI 1.00 to 1.04—polystyrene chains, and the SEC‐MALLS data of these chains confirm the accurate control on predetermination in the number of arms up to 48 of star polymers. The specific refractive index increment (dn/dc) of the polymers is found to be decreased with decreasing weight fraction of core. The transmission electron microscope (TEM) and atomic force microscopy (AFM) images and hydrodynamic radius of chosen polymers confirm the two different chain growth fashions leading to the formation of star polymers as discrete nanoparticle in the case of initiator in which TEMPO is anchored and formation of peripherally low entangled short chains in the case of initiators in which TEMPO is end‐capped.

Multimodal Plasmonic Assay of Copper(II) Ion via Stimuli-Responsive State Transformation of Silver Molecular Nanoparticles

“…Existing MNPs, such as fullerene and polyhedral oligomeric silsesquioxane (POSS), have been demonstrated as essential building blocks for the precise synthesis of giant molecules or well-defined nanostructures. ,,− On the other hand, MNPs exhibit unique properties distinct from conventional molecules. A variety of novel MNPs have been prepared. − ,− Among MNPs, gold and silver MNPs have the potential to be alternatives of their well-explored larger counterparts, plasmonic nanoparticles (PNPs). Au and Ag PNPs possess strong surface plasmon resonance absorption from the visible to near-infrared region .…”