Solution properties and electrospinning of polyacrylamide and ε-polylysine complexes

Abstract The key to achieve electrospinning easiness and defect-free fibers for biopolymers mainly lies in the tune of solution properties. In this work, we uncovered the tunable effects of e-polylysine (ePL, Mw ∼4000 g/mol) on improving electrospinning easiness and harvesting defect-free fiber for ultra-high molecular-weight polyacrylamide (PAAm, Mw ∼4,000,000 g/mol) by characterizing solutions properties and electrospinning morphologies of their complexes. The function of ePL is to promote PAAm solvation by displacing the intra-molecular hydrogen bonds among –CONH2 groups, resulting in much looser structural domains. We also found a critical molar ratio (Rc) at 0.9%, the repeated units of ePL against that of PAAm. Above the Rc, ePL can significantly decrease PAAm solution viscosity and facilitate the harvest of defect-free fibers, ascribing to the transformation of their interactions from NH3+/COO− ion pairs to NH3+/-CONH2 hydrogen bonds. At last, we summarized from electrospinning of biopolymer complexes that the enhancement of solvation and “entanglement” are considered as the two fundamentals to improve electrospinning easiness and harvest defect-free fibers.