Under the joint supervision of Professors Li Liangbin and Cui Kunpeng, our postdoctoral researcher Zhang Yunhan and colleagues have, for the first time, unveiled the molecular dynamics of polyvinyl butyral (PVB)—the core material in automotive laminated glass—under mechanical stress. This study, published in the leading international journal Soft Matter, provides a new perspective on the evolution of hydrogen-bond networks in amorphous polymers under mechanical loading.
Using coarse-grained molecular dynamics simulations, the research team captured the dynamic changes of PVB during tensile deformation. Near the glass transition temperature, polymer chains were observed to undergo “slippage” under stress. This microscopic motion led to the breaking of intramolecular hydrogen bonds (“handshakes” within a chain), while unexpectedly promoting the formation of intermolecular hydrogen bonds (“handshakes” between chains)—a process akin to simultaneously “dismantling bridges” and “building new ones” at the molecular level.
By systematically varying three key parameters—vinyl alcohol (VA) content (which regulates hydrogen-bond density), block-structure regularity, and tensile strain rate—the researchers found that increasing VA content significantly enhances chain rigidity. During stretching, this rigidity facilitated more pronounced chain unfolding, which in turn strongly influenced hydrogen-bond lifetimes. The most groundbreaking discovery was that a net reduction in the total number of hydrogen bonds occurred just before fracture. However, after fracture, the hydrogen-bond network exhibited self-healing and reorganization through a mechanical–thermal coupling effect. This dynamic “destruction–reconstruction” balance mechanism provides a plausible explanation for the exceptional energy absorption capacity of PVB materials.
The study not only overcomes the technical challenge of monitoring hydrogen-bond dynamics in amorphous polymers but also establishes a quantitative predictive model linking molecular structure–hydrogen-bond networks–mechanical performance, laying a solid scientific foundation for the rational design of next-generation high-performance PVB films.
This work was supported by the China Postdoctoral Science Foundation (Grant 2023M743377), the Fundamental Research Funds for the Central Universities (Grant WK2310000119), the Hefei Municipal Major Special Guidance and Entrustment Project “Research and Development of Polyvinyl Butyral (PVB) Films for Automotive Safety Glass,” and the Hefei Municipal Major Science and Technology Special ‘Revealing the List and Taking Command’ Project (Grant 2022-SZD-005).
Y. Zhang et al. Investigating hydrogen bonding in poly(vinyl butyral) copolymers near glass-transition temperature under uniaxial stress: acoarse grained molecular dynamics study. Soft Matter, 2025,Advance Article
Paper Link：https://pubs.rsc.org/en/Content/ArticleLanding/2025/SM/D5SM00431D
