Quantifying the hydrogen bond(H-bond)strength of polymers is essential for rational design of advanced materials.However,direct measurement remains challenging because of the structural complexity of polymers and the ...Quantifying the hydrogen bond(H-bond)strength of polymers is essential for rational design of advanced materials.However,direct measurement remains challenging because of the structural complexity of polymers and the weak nature of H-bonds.Vacuum-based singlemolecule force spectroscopy(Vac-SMFS)offers a new and precise approach for such measurements.Using polyallylamine(PAAm)as a model polymer,the intrinsic strength(i.e.,strength without external influences)of representative N―H…N H-bonds was quantified to be about 5.25 kJ·mol^(–1).Comparative Vac-SMFS analysis across different polymer systems revealed that the N―H…N H-bonds in PAAm are unexpectedly stronger than the N―H…O H-bonds in poly(N-isopropylacrylamide)(PNIPAM)and the O―H…O H-bonds in poly(hydroxyethyl methacrylate)(PHEMA).This trend contrasts with that of established small-molecule systems.These results highlight how side-chain length and spatial configuration dictate polymer H-bond strengths,expanding the fundamental knowledge of polymer interactions and enabling the rational design of next-generation functional materials.展开更多
基金financially supported by the National Natural Science Foundation of China(No.22273079)Fundamental Research Funds for the Central Universities(No.2682025ZTPY004)。
文摘Quantifying the hydrogen bond(H-bond)strength of polymers is essential for rational design of advanced materials.However,direct measurement remains challenging because of the structural complexity of polymers and the weak nature of H-bonds.Vacuum-based singlemolecule force spectroscopy(Vac-SMFS)offers a new and precise approach for such measurements.Using polyallylamine(PAAm)as a model polymer,the intrinsic strength(i.e.,strength without external influences)of representative N―H…N H-bonds was quantified to be about 5.25 kJ·mol^(–1).Comparative Vac-SMFS analysis across different polymer systems revealed that the N―H…N H-bonds in PAAm are unexpectedly stronger than the N―H…O H-bonds in poly(N-isopropylacrylamide)(PNIPAM)and the O―H…O H-bonds in poly(hydroxyethyl methacrylate)(PHEMA).This trend contrasts with that of established small-molecule systems.These results highlight how side-chain length and spatial configuration dictate polymer H-bond strengths,expanding the fundamental knowledge of polymer interactions and enabling the rational design of next-generation functional materials.
