40-year-old prediction of how plastics 'mix' confirmed for the first time
A "mixing" phenomenon between plastic layers that had been predicted only in theory for 40 years has now been experimentally confirmed.
After 40 years of theoretical predictions, researchers have experimentally confirmed a phenomenon where the mixing of plastic layers can be controlled by altering the polymer's topology. A team led by Professor So Youn Kim from Seoul National University College of Engineering and Professor Kyoung Taek Kim from SNU College of Natural Sciences discovered that changing a linear polymer into a ring-shaped one enhances interfacial mixing at the interface between two plastic layers.
This finding, published in ACS Central Science, demonstrates that polymer topology, or architecture, can directly influence interfacial mixing, a concept proposed theoretically approximately 40 years ago. The research focused on polylactide (PLA) polmer, a biodegradable plastic, and showed that when one polymer was altered from linear to ring architecture, the interfacial mixing width increased from 1.9 nm to 5.0 nm, a 2.6-fold increase.
The study validates the topological entropy effect, where a long chain passing through a ring polmer can increase molecular configurations and improve interfacial miscibility. The findings could lead to new design principles for controlling the miscibility and stability of plastic interfaces, potentially eliminating the need for additional compatibilizers in multilayer films and coatings.
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