Synthesis of silica/PAA NPs via combining RAFT polymerization and thiol‐ene click reaction and postpolymerization modifications with arsenazo (III)

Abstract

Silica/poly(acrylic acid)/arsenazo core‐shell nanoparticles were synthesized by reversible addition‐fragmentation chain transfer (RAFT) polymerization combined with thiol‐ene grafting method. Thiol‐terminated poly(acrylic acid) (PAA‐SH) was prepared by RAFT polymerization of the acrylic acid using azobisisobutyronitrile (AIBN) initiator. The molecular weight and structure of this polymer were characterized by gel permeation chromatography and Fourier transform infrared. Methacrylate‐functionalized silica nanoparticles (MPS‐silica NPs) were prepared by the functionalization of silica nanoparticles with 3‐(trimethoxysilyl)propyl methacrylate in dried toluene. PAA‐SH was coupled to MPS‐silica NPs by click reaction in the presence of AIBN. The chemical nature and structure of product were characterized by a multitechnique approach. The prepared particles consist of silica cores, about 45 nm in size, surrounded by stable PAA shells. Furthermore, after conversion of arsenazo (III) to arsenazoNH2, it was successfully clicked on the surface of PAA shell. It is realized that the postpolymerization kinetics can be tuned by several parameters such as the temperature of reaction medium and concentration of arsenazoNH2. These nanoparticles could be useful in sensor and indicator applications due to the interesting properties that arsenazo has against specific metal ions. Furthermore, the described results give new insights in the synthesis and characterization of silica polymer core‐shell nanoparticles.