Covalent adaptable networks impart smart processability to multifunctional highly filled polymer composites

To tackle the challenge of manufacturing highly filled composite materials via melt compounding and injection molding , the authors proposed a novel approach based on Diels-Alder (DA) chemistry. Polycaprolactone oligomers (PCL olig , M w = 2000 g/mol) were firstly crosslinked by DA bonds, and then the resultant network PCL olig -DA was also connected to maleimide functionalized Al 2 O 3 particles (Al 2 O 3 -M) via DA bonds. Upon being heated to the retro-DA reaction temperature, the covalent adaptable composite network exhibited low viscosity due to de-crosslinking, enabling melt processing and well dispersion of high-concentration fillers. During the subsequent cooling, the composite network was regained because of DA reaction, benefiting increase of the composite’s strength . Consequently, the contradictory requirements for molecular weight of matrix polymer under the circumstances, which had better to be as low as possible during the manufacturing but as high as possible in the ultimate composites, were skillfully satisfied.