A new water-soluble lignin incorporation enhanced the barrier performance of liquid mulching film

In modern agriculture, the eco-friendly liquid mulching film is a promising alternative to traditional plastic mulching films but challenged by its limited barrier performance. In this work, a facile cyanoethylation technique route was proposed to produce water-soluble lignin from industrial waste lignin, which was further used as a biomimetic bonding adhesive and functional additive to cellulose nanowhisker (CNW) to form the building block of liquid mulching film. It was shown that at low degree of cyanoethylation, the water-solubility was improved through disrupting the strong hydrogen bonding of lignin, while remaining its UV light barrier and antioxidant activity. The well designed liquid mulching film fabricated with cyanoethyl lignin (CEL) coated CNW (CEL@CNW) building block and polyvinyl alcohol (PVA) matrix showed excellent UV barrier (reached ∼ 0 % transmittance at 200 nm with 10 wt% of CEL@CNW) and oxygen barrier ability (oxygen transmission rate reached ∼ 0.12 cm3 m−2 d−1 kPa−1 with 5 wt% of CEL@CNW), which could be used for the protection of photo-sensitive avermectin pesticide against photo-degradation. The real application potential of the fabricated PVA/ CEL@CNW liquid mulching film was verified through the good soil water resistance property and the facilitation of corn seed germination and seedling growth. It was proposed that the CEL incorporation mediated the layered structure of liquid mulching film thus significantly enhancing its overall barrier performance. This work provided a new strategy to valorize industrial waste lignin through water-soluble lignin pursuing, while tailoring a technique platform for the fabrication and application of liquid mulching film toward a more sustainable agriculture.