Hydrophilicity improvement of mercerized bacterial cellulose films by polyethylene glycol graft

• Mercerized bacterial nanocellulose (BNCm) was grafted to polyethylene glycol with different molar ratios (BNCm-PEGs).
• Crystallinity of BNCm was preserved after grafting with PEGs.
• Grafting of PEG was observed on C-2, C-3 and C-6 of BNCm mainly on amorphous zones.
• Nanofilms produced with BNCm-PEG showed an increased free energy of surface comparatively to BNCm.
• All BNCm-PEG films retained the biocompatibility of BNCm films.

In this work, polyethylene glycol (PEG), of tree distinct molar masses (200, 300 and 400 g mol−1), was grafted onto mercerized bacterial nanocellulose (BNCm) and applied to produce nanofilms (BNCm-PEG). The products BNCm-PEG were characterized by NMR and thermal analysis. Solid-state NMR and X-ray diffraction analyses exhibited no significant differences in index of BNCm-PEG derivatives compared to BNCm, indicating that grafting reaction did not modify the BNCm crystalline structure. The apparent contact angle of the films showed that BNCm-PEG films exhibited a pronounced increase in the polar components (BNCm: 8.1 mN m−1 vs BNCm-PEG400: 29.4 mN m−1), and a decrease in dispersive components (BNCm: 41.7 mN m−1 vs BNCm-PEG400: 35.2 mN m−1) of the surface free energy. The BNCm-PEG films were more hydrophilic than BNCm and retained the biocompatibility with L929 fibroblast cells culture.