English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The glass transition is a long-standing unsolved problem in materialsscience. For polymers, our understanding of glass-formation is particularlypoor due to the added complexity of chain connectivity and flexibility;structural relaxation of polymers thus involves a complex interplay betweenintra- and inter-molecular cooperativity. Here we study how the glasstransition temperature Tg varies with molecular weight M for different polymerchemistries and chain flexibilities. We find that Tg(M) is controlled by theaverage mass (or volume) per conformational degree of freedom, and that a`local' molecular relaxation (involving a few conformers) controls thelarger-scale cooperative alpha relaxation responsible for Tg. We propose thatdynamic facilitation where a `local' relaxation facilitates adjacentrelaxations, leading to hierarchical dynamics, can explain our observationsincluding logarithmic Tg(M) dependences. Our study provides a new understandingof molecular relaxations and the glass transition in polymers, which paves theway for predictive design of polymers based on monomer-scale metrics.

Cooperative intramolecular dynamics control the chain-length-dependent glass transition in polymers