Facile synthesis of crosslinked core/shell silver nanoparticles with significantly improved thermal stability

• PS-b-PCMS-b-PS triblock copolymer was synthesized by RAFT polymerization.
• Ag NPs protected by a crosslinked PCMS shell and PS brushes were prepared.
• The method combined in-situ reduction and inner-shell crosslinking reaction.
• The Ag NPs were stable in solution for at least 18 h while being heated at 110 °C.
• The preparation of metal NPs with high thermal stability is promising to scale-up.

A facile preparation of highly thermal stability silver nanoparticles (Ag NPs) protected by a crosslinked poly(p-chloromethyl styrene) (PCMS) shell and polystyrene (PS) brushes was reported in this work. Firstly, a triblock copolymer, PS-b-PCMS-b-PS, was synthesized by sequential reversible addition-fragmentation transfer (RAFT) polymerization of styrene and p-chloromethyl styrene using a trithiocarbonate chain transfer agent. Secondly, Ag NPs were obtained by in-situ reduction of silver nitrate using trithiocarbonate-containing PS-b-PCMS-b-PS as the stabilizer. Finally, ethylene diamine was used to quaternize and crosslink the PCMS inner-shell, leaving the outer-shell PS brushes preventing particle aggregation. Due to protection of the crosslinked PCMS inner-shell, Ag NPs were stable in solution for at least 18 h while being heated at 110 °C. Therefore, this method of combined in-situ reduction and inner-shell crosslinking is promising to scale-up the preparation of metal nanoparticles with good dispersibility and thermal stability, which has still remained challenging so far.

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