PLA/AcrylPEG/L101 blend morphology Reactive extrusion of poly(lactide) with low molecular weight acryl-functionalized poly(ethylene glycol). An original and effective methodology to toughen poly(lactide) Georgio Kfoury 1, 2, Fatima Hassouna 1, Valérie Toniazzo 1, Jean-Marie Raquez 2, David Ruch 1, Philippe Dubois 2 1 Department of Advanced Materials and Structures (DAMS), Centre de Recherche Public Henri Tudor, rue Bommel 5 (ZAE Robert Steichen), 4940 Hautcharage, LUXEMBOURG 2 UMons Research Institut for Materials Science and Engineering, Laboratory of Polymeric and Composite Materials, University of Mons (UMONS), Place du Parc 23, 7000 Mons, BELGIUM State of the art Poly(lactide) (PLA) is one of the most extensively studied biodegradable thermoplastics derived from renewable resources. One of the main drawbacks of PLA is its inherent brittleness, which limits its applications. Plasticization of PLA with low molecular weight poly(ethylene glycol) (PEG) is currently carried out to sustain this issue, but it results the migration of plasticizer at high PEG loadings. State of the art Poly(lactide) (PLA) is one of the most extensively studied biodegradable thermoplastics derived from renewable resources. One of the main drawbacks of PLA is its inherent brittleness, which limits its applications. Plasticization of PLA with low molecular weight poly(ethylene glycol) (PEG) is currently carried out to sustain this issue, but it results the migration of plasticizer at high PEG loadings. Conclusions High grafting extent of AcrylPEG: Formation of a low AcrylPEG oligomers (DP~7) fraction (extracted by Soxhlet) and a highly grafted fraction of poly(AcrylPEG) in PLA (not extracted by Soxhlet) Limited plasticizer migration after DMA It comes out a much limited migration of the plasticizer, which needs to be quantified by further physical aging. Efficient plasticization/ductility and improved impact resistance with increasing L101 In situ generation of particular rubbery micro- and nano-domains : soft poly(acrylPEG)-rich cores having an “immiscibility gradient” with surrounding PLA due to the grafting reaction. Conclusions High grafting extent of AcrylPEG: Formation of a low AcrylPEG oligomers (DP~7) fraction (extracted by Soxhlet) and a highly grafted fraction of poly(AcrylPEG) in PLA (not extracted by Soxhlet) Limited plasticizer migration after DMA It comes out a much limited migration of the plasticizer, which needs to be quantified by further physical aging. Efficient plasticization/ductility and improved impact resistance with increasing L101 In situ generation of particular rubbery micro- and nano-domains : soft poly(acrylPEG)-rich cores having an “immiscibility gradient” with surrounding PLA due to the grafting reaction. Acknowledgments Thanks to the AMS Department of CRP Henri Tudor and the Laboratory of Polymeric and Composite Materials (LPMC) for the technical and scientific supports and the Fond National de la Recherche (FNR) for the financial support. Acknowledgments Thanks to the AMS Department of CRP Henri Tudor and the Laboratory of Polymeric and Composite Materials (LPMC) for the technical and scientific supports and the Fond National de la Recherche (FNR) for the financial support. Molecular characterization Original approach In situ polymerization and free-radical grafting of acryl- functionalized PEG onto PLA backbone via reactive extrusion aims to reduce the migration of the plasticizer. Original approach In situ polymerization and free-radical grafting of acryl- functionalized PEG onto PLA backbone via reactive extrusion aims to reduce the migration of the plasticizer. PLA PLA/AcrylPEG/L101 PLA/AcrylPEG Mechanical properties Material/Blend (compositions in wt. %) Extracted ftaction by Soxhlet (%) T g (°C) DMA Storage Modulus E’ at 20°C (MPa) Impact energy a (kJ/m 2 ) Elongation at break b (%) PLA PLA/L101 (99.5/0.5) PLA/AcrylPEG (80/20) PLA/AcrylPEG/L101 (79.5/20/0.5) (No break) Reactive extrusion (REx) Drying PLA under vacuum at 60°C over night Dry PLA Dry material AcrylPEG + L101 Compression moulding on a Carver manual press : Moulding Temperature = 180°C; Moulding time = 10 min REx under N 2 co-rotating twin- screw extruder DSM Xplore (15cc): T melt ~ 175°C; scew speed = 100 rpm; REx time = 5 min PolyAcrylPEG grafted on PLA AcrylPEG OligoAcrylPEG (DP~7) Efficient plasticization resulting in improved ductility and impact resistance with increasing L101 amount In the absence of L101, AcrylPEG migrated to the surface of the specimen after DMA, while it was not the case in the presence of L101 Soft domains (after cryofracture) made of poly(acrylPEG) (core) surrounded with an immiscibility gradient are observed due to the grafting of acrylPEG on PLA (shell) Core-shell microdomains played a stress concentrator role and impact energy dissipation  fracture inhibitors Formation of a low AcrylPEG oligomers (DP~7) fraction (extracted by Soxhlet) Formation of a highly grafted fraction of poly(AcrylPEG) in PLA (not extracted by Soxhlet in methanol) Lupersol101 (L101) 715 nm 440 nm