Near-infrared-driven photothermal atom transfer radical polymerization.

Area of Science:

• Polymer Chemistry
• Nanotechnology
• Materials Science

Background:

• Reversible-deactivation radical polymerization (RDRP) offers control over polymer synthesis.
• Photo-ATRP and photo-RAFT are common RDRP methods but limited by UV light and oxygen sensitivity.
• Biological applications require polymerization methods compatible with aqueous, aerobic conditions.

Purpose of the Study:

• To develop a photothermal method for controlled ATRP and RAFT polymerization in aqueous media under aerobic conditions.
• To utilize gold nanobipyramids (NBPs) for localized heating upon near-infrared (NIR) light irradiation.
• To overcome limitations of existing photo-RDRP techniques for broader applications.

Main Methods:

• Gold nanobipyramids (NBPs) were synthesized and their morphology tuned for efficient photothermal conversion.
• Near-infrared (NIR) light irradiation (780 nm) of NBPs generated localized heating.
• A water-soluble azo initiator (AAPH) was used to initiate polymerization upon photothermal heating.
• Controlled ATRP of OEOMA500 and photo-RAFT polymerization of various monomers were performed in aqueous solution under air.

Main Results:

• The photothermal approach enabled well-controlled ATRP and RAFT polymerization in aqueous solution under aerobic conditions.
• NIR light irradiation of NBPs efficiently triggered radical generation and polymerization.
• The photothermal ATRP demonstrated excellent temporal control with rapid on/off switching via NIR light modulation.
• The method was versatile, successfully polymerizing different monomer classes using both ATRP and RAFT.

Conclusions:

• A robust, nanotechnology-enabled photothermal approach for RDRP in aqueous media under aerobic conditions was established.
• This method overcomes key limitations of traditional photo-RDRP, such as UV light dependence and oxygen sensitivity.
• The developed technique opens new avenues for advanced materials synthesis and high-throughput applications.