Characterization of dual nano-size effects of ACC-cellulose nanofibrils on crystallization behavior of hydrophilic poly(vinyl alcohol)

Abstract

This study attempts to clarify thermodynamic quantification on interaction between poly(vinyl alcohol) (PVA) and wood-derived cellulose nanofibrils (CNFs) obtained by aqueous counter collision (ACC) method. Aqueous mixtures of PVA/ACC-CNFs with various fiber widths were cast as the target materials. The interfacial interactions between the two components were characterized through thermodynamic evaluation of the crystalline PVA component as a probe in the cast mixture. As the result, surface properties of the ACC-CNFs found to reflect on the crystallization behavior of the interacted PVA component, resulting in dual nano-size effects of either diluent or nucleating agent. Melting point depression behaviors of the PVA component indicated that ACC-CNFs with thinner widths induced nucleation effects on PVA crystallization, whereas ACC-CNFs with ca. 100 nm in width encouraged diluent effects on PVA components. It is noted that this trend found to be reverse to the case for PVA/ACC-CNFs of bacterial nanocellulose previously reported.

Adsorption of Janus-Type Amphiphilic Cellulose Nanofibrils onto Microspheres of Semicrystalline Polymers

“…This approach was based on Hoffman−Weeks plots used for mixing semicrystalline/noncrystalline (amorphous) polymers. [38][39][40]45 The difference in the two tentative T m eq (ΔT m eq ) values shown in Figures 2 and 5 can be regarded as an indication of the thermodynamically metastable states present in the i-PP particles coated with ACC-CNFs. That is, the ΔT m eq reflects the thermodynamic affinity between the hydrophobic semicrystalline polymer and the Janus-type amphiphilic ACC-CNFs.…”

“…Among the ACC-CNFs tested, the CNF from microcrystalline cellulose (ACC-MCC) was the least hydrophobic and ACC-BNC derived from bacterial pellicles was the most hydrophobic. 25,39,40 Hydrophilic TEMPO-oxidized cellulose nanofibrils (TOCNs) 14,15 were also investigated for their ability to coat i-PP particles [TEMPO = (2,2,6,6-tetramethylpiperidin-1-yl)oxyl].…”

“…To eliminate the morphological contributions to the two different melting points, a tentative equilibrium T m ( T m eq ) was obtained by plotting the observed T m against the isothermal crystallization temperature, as shown in Figure . This approach was based on Hoffman–Weeks plots used for mixing semicrystalline/noncrystalline (amorphous) polymers. − , …”

“…There have been numerous reports on the miscibility of multicomponent polymeric materials from the following viewpoints: , (i) spectroscopic characterization of morphological changes; (ii) relaxation phenomena with various stimuli in the solid state; and (iii) thermodynamic approaches. − The phenomenon of melting point depression has been used to probe interaction energies that are dependent on the volume fraction and temperature in mixtures of semicrystalline polymers . In previous studies, the authors evaluated miscibility and the formation of interactions between composite films comprising ACC-CNFs and poly­(vinyl alcohol) (PVA). , The present study focused on the interaction between the hydrophilic plane of ACC-CNFs and hydrophilic PVA molecules. As mentioned above, ACC-CNFs are Janus-type amphiphilic fibers that can be used to coat i-PP. − However, the affinity of ACC-CNFs for hydrophobic semicrystalline polymers has still not been examined in detail.…”

“…38 In previous studies, the authors evaluated miscibility and the formation of interactions between composite films comprising ACC-CNFs and poly(vinyl alcohol) (PVA). 39,40 The present study focused on the interaction between the hydrophilic plane of ACC-CNFs and hydrophilic PVA molecules. As mentioned above, ACC-CNFs are Janus-type amphiphilic fibers that can be used to coat i-PP.…”