Hydrogen-Bonding-Induced Clusteroluminescence and UCST-Type Thermoresponsiveness of Nonconjugated Copolymers

Stimuli-responsive light-emitting polymers (SRLEPs) have many promising applications. However, the synthesis of SRLEPs from nonconjugated and water-soluble monomers remains a challenge. Herein, for the first time, nonconjugated luminescent polymers with an upper critical solution temperature (UCST) in aqueous solution are reported. The polymer is synthesized through copolymerization of a strong hydrogen-donating monomer, acrylic acid (AAc), and a strong hydrogen-accepting monomer, N-vinylcaprolactam (NVCL). The polymer-polymer hydrogen-bonding rigidifies the chain conformation and enhances the clustering of the heteroatoms and carbonyl groups, resulting in an improved clusteroluminescence. Meanwhile, the polymer-polymer hydrogen bonding also brings in dynamic chain association that can be switched with temperature, yielding a UCST-type thermoresponsiveness in aqueous solution. This work demonstrates a novel and facile method of designing SRLEPs through tailoring the hydrogen bonds in the polymer. The properties of clusteroluminescence and thermoresponsiveness of the AAc-NVCL copolymers may render themselves with applications as temperature-sensitive biosensing.

Automated summary

Nonconjugated luminescent polymers with an upper critical solution temperature (UCST) in aqueous solution have been synthesized through copolymerization of a strong hydrogen-donating monomer, acrylic acid (AAc), and a strong hydrogen-accepting monomer, N-vinylcaprolactam (NVCL). The polymer demonstrates improved clusteroluminescence and thermoresponsiveness, making it suitable for temperature-sensitive biosensing applications.