Functional Flexible Polyvinyl Chloride Plastics via the Addition of Core‐Shell Star Copolymers <scp>CA</scp> ‐ <scp>HPCL</scp>

ABSTRACT Polyvinyl chloride (PVC) is an important plastic material. How to enhance the stability of plasticizers in PVC materials is crucial. In this work, internal plasticization was achieved through the ring‐opening polymerization (ROP) of polycaprolactone (PCL) grafted from the unsubstituted hydroxyl groups of cellulose acetate (CA). A series of hyperbranched copolymers (CA‐HPCL) with CA acetate‐rich hard core and PCL‐rich soft shell were prepared. Under similar elongation at break conditions, PVC plasticized with CA‐HPCL shows higher modulus, strength, and toughness than linear plasticized PVC and other traditional low‐molar‐mass plasticizers without hard cores. The obtained plasticized PVC material exhibits a high modulus of approximately 30 MPa while ensuring an elongation at break of more than 300%. Further DSC and FTIR characterizations, combined with a comparison with the linear C 5 H 12 O‐PCL plasticizer, reveal that this high rigidity is attributed to the physical cross‐linking effect of CA‐HPCL on PVC chains. Meanwhile, the migration stability test shows that CA‐HPCL exhibits excellent anti‐migration properties in PVC matrix. The migration rates of all CA‐HPCL‐PVC samples are lower than 5%, which is only 0.072 times that of DOP‐PVC. Therefore, such films with excellent flexibility, elongation and high modulus are expected to be widely applied in the medical industry.