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Upcycling by grafting onto semi‐crystalline polymers using supercritical CO 2
Author(s) -
Camarda Daniel S.,
Lampe Matthew J.,
Lesser Alan J.,
Desbois Philippe,
Stoll Klaus,
Gabriel Claus,
Konradi Rupert
Publication year - 2021
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.51203
Subject(s) - materials science , polystyrene , polymer chemistry , polymer , copolymer , tacticity , polymerization , grafting , polyamide , amorphous solid , chemical engineering , polyethylene , polypropylene , supercritical fluid , composite material , organic chemistry , chemistry , engineering
The creation of graft copolymers by selectively grafting a second polymer to the amorphous fraction of a semi‐crystalline polymer in supercritical CO 2 is demonstrated herein. The graft copolymer is synthesized by free radical polymerization of a vinyl monomer within the semi‐crystalline polymer below its melt temperature. Such conditions afford selective grafting on the amorphous regions (block “B”) while leaving the crystalline domains (block “A”) unmodified. Accordingly, unique A‐B, A‐B‐A, A‐B‐A‐B‐A, and so forth. block structures are formed. In this work, styrene is polymerized within polyamide 6, polyethylene terephthalate, and isotactic polypropylene. Purification of these material is performed to remove the un‐grafted homopolymer, allowing for determination of the graft yield, the portion of polymer which covalently bonds to the semi‐crystalline matrix. Grafting yields achieved in polyamide 6, polyethylene terephthalate, and isotactic polypropylene were 98%, 59%, and 15%, respectively. Property enhancements were observed upon further characterization of polystyrene‐polyamide 6 copolymers, including high glass transition temperatures, the ability to be remelted, and tunable grafting molecular weight. Additionally, hydrophobicity is controlled by varying polystyrene composition. The remarkable range of accessed properties demonstrates this as a potential route to upcycling plastics.