In Situ Nanofibrillar Networks Composed of Densely Oriented Polylactide Crystals as Efficient Reinforcement and Promising Barrier Wall for Fully Biodegradable Poly(butylene succinate) Composite Films

Developing a sustainable and environmently friendly scheme to fabricate fully degradable barrier films with robust mechanical properties is still a great challenge. Here, we first put forward a methodology that through taking advantage of an elongational flow field followed by woven hot compaction, in situ nanofibrillar networks of polylactide (PLA) are creatively constructed within a poly(butylene succinate) (PBS) matrix serving as an efficient "barrier ball" and reinforcement. The in situ PLA nanofibrils tend to overlap to constitute into a kind of interwoven network, in which highly oriented PLA lamellae are regularly arranged. Simultaneously, this network produces a spatial confinement effect on the crystallization of PBS, resulting in a confined environment around the nanofibrillar networks. This unparalleled hierarchical structure can availably attribute to an exceptional gas barrier and mechanical properties of the composite films. Ultimately, the oxygen permeability coefficient of the composite films can be reduced more than 60%, and the tensile strength increases nearly twice compared with that of pure PBS film. Meanwhile, the ductility certainly does not deteriorate. Of more practicable significance is that this processing method provides a new route to manufacture multiphase biopolymers with high performance and multifunctional sustainability.