Summary: Grafting of terminal epoxide‐functionalized polystyrene onto poly[styrene‐co‐(2‐hydroxyethyl methacrylate)] or poly[(butyl acrylate)‐co‐(2‐hydroxyethyl methacrylate)] backbones was carried out by coupling reactions catalyzed by boron trifluoride. The functionalized backbones were prepared by free radical copolymerization of 2‐hydroxyethyl methacrylate (HEMA) with styrene or butyl acrylate. For the synthesis of terminal functionalized polymer chains a side reaction of the TEMPO‐mediated free radical polymerization of methacrylates could be used successfully to convert TEMPO‐terminated polymers into terminal epoxide‐functionalized polymers by the use of glycidyl methacrylate. The number of epoxide units attached to the backbone was directly related to the TEMPO concentration during the disproportionation reaction. Taking P(S‐co‐HEMA) as well as P(BuA‐co‐HEMA) backbones in coupling reactions with different epoxy‐functionalized polystyrenes in the presence of boron trifluoride, graft polymers with up to 7 and 37 side chains per backbone were produced.Molecular weight distribution curves of a linking experiment between P(BuA‐co‐HEMA) backbones and epoxide‐functionalized polystyrene side chains.magnified imageMolecular weight distribution curves of a linking experiment between P(BuA‐co‐HEMA) backbones and epoxide‐functionalized polystyrene side chains.
Summary: Coupling reactions between terminal functionalized polymer chains were chosen for the synthesis of star‐like polymers consisting of polystyrene and polystyrene‐block‐poly[styrene‐co‐(butyl acrylate)] arms. For the preparation of terminal functionalized polymer chains a side reaction of the 2,2,6,6‐tetramethylpiperidine‐N‐oxyl (TEMPO) mediated free radical polymerization of methacrylates could be used successfully to convert TEMPO terminated polymers into end functionalized polymers. The number of functionalized monomer units attached to the polymer chain is directly related to the TEMPO concentration during this reaction. Different polystyrenes and polystyrene‐block‐poly[styrene‐co‐(butyl acrylate)] block copolymers were functionalized with a variable number of epoxide and alcohol groups at the chain end. For the determination of the optimal reaction parameters for the coupling reactions between these polymer chains, epoxy functionalized polystyrenes were converted with hydroxy functionalized polystyrenes under basic and acidic conditions. By activation with sodium hydride or boron trifluoride star‐like polymers were synthesized under mild conditions. The transfer of the reaction conditions to coupling reactions between end functionalized polystyrene‐block‐poly[styrene‐co‐(butyl acrylate)] copolymers showed that star‐like polymers with more than 12 arms were formed using boron trifluoride as activating agent.image
ZUSAMMENFASSUNG:Hochpolymere Verarbeitungshilfsmittel auf der Grundlage von PMMA werden seit vielen Jahren bei der Verarbeitung von Hart-PVC eingesetzt. Die damit erreichbaren Verbesserungen sind bekannt. Wenig bekannt sind dagegen die Wirkungsmechanismen. Die Verbesserung des Aufschmelzverhaltens von Hart-PVC wird auf die Erhohung des Reibungsbeiwertes PVC/Metall und die Umwandlung von einem nichtwandhaftenden in einen wandhaftenden Kunststoff zuruckgefuhrt. Diese Umwandlung erklart auch, warum die Zugabe von PMMA-Verarbeitungshilfsmitteln bei der Extrusion das Auftreten des Schmelzbruches vermeidet. Beim SpritzgieDen laDt sich die Vermeidung von Ablosungen der Schmelze nicht allein durch das verbesserte Haften erklaren, sondern auch durch die Anreicherung des PMMA-Zusatzmittels in den auDeren Schichten der eingespritzten Schmelze.
SUMMARY:High-molecular PMMA-based processing aids are used for rigid PVC for many years. Their possible performances are known. However, the mechanisms are largely unexplained.The improvement of plastifying behaviour of rigid PVC is based on the increase of
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.