High-strength and water resistance polyvinyl alcohol fibers modified with lignin nanoparticles and boron nitride nanosheets@hyperbranched polylysine

Development on sustainable and inexpensive polymer fibers with high mechanical and water resistance properties has garnered significant attention in infrastructure application. Herein, lignin nanoparticles (LNP) were used as a modifier, boron nitride nanosheets (BNNS)@hyperbranched polylysine (HBPL) obtained were regarded as the cooperative modifier, and then polyvinyl alcohol (PVA)/LNP/BNNS@HBPL composite fibers were fabricated successfully by wet and dry spinning. Vast free hydrophilic hydroxyl groups in PVA decreased due to hydrogen bonding interactions among LNP, BNNS@HBPL, and PVA, thereby attenuating intramolecular and intermolecular hydrogen bonding within PVA. Thus, significant improvements on mechanical properties for PVA/LNP/BNNS@HBPL composite fibers were achieved simultaneously, which maintained excellent water resistance in air. Notably, with only 0.5 wt% LNP and 0.3 wt% BNNS@HBPL, the tensile strength and initial modulus reached 12.2 cN/dtex and 153.8 cN/dtex, respectively, representing improvements of 74.2 % and 44.8 % compared to pure PVA fibers. Furthermore, the contact angle was 107.3°, 41.2° higher than pure PVA fiber. The remarkable enhancements make the prepared PVA/LNP/BNNS@HBPL a promising candidate for inexpensive fiber-reinforced concrete.