Lignin containing cellulose nanofibril application in pMDI wood adhesives for drastically improved gap-filling properties with robust bondline interfaces

•LCNF was prepared as an effective reinforcing material for pMDI wood adhesives.•The resulting adhesives showed significantly improved mechanical performance.•Dramatically enhanced gap-filling properties and robust bondline interphases were both achieved after incorporating LCNF.•Sustainable LCNF could allow pMDI to be more versatile with broader applications.