Effect of Hydrogen Bonding on Dynamic Rheological Behavior of PVA Aqueous Solution

Abstract

The rheological behavior of polyvinyl alcohol (PVA) aqueous solution is crucial to optimizing the processing technology and performance of PVA products. In this paper, the dynamic rheological behavior of PVA aqueous solution was investigated in detail. PVA solution with a concentration of 10 wt% showed unnormal rheological behaviors, that is, the liquid-like behavior in the high frequency (ω) region and the solid-like behavior in the low ω region. A storage modulus (G′) plateau appears in the relatively low ω region as a gel with a network structure. Different from conventional hydrogel, this plateau has a low modulus, and the corresponding size of the relaxation unit is estimated to be 554 nm, being higher than the size of a whole PVA chain. It is believed that the network mesh is formed by the intermolecular hydrogen bonding interactions among PVA chains. The relaxation time of these meshes is longer than the reptation time of a PVA chain. Based on the relaxation spectrum and calculation analysis, it is found that the destruction of intermolecular hydrogen bonds, such as by heating up, adding sodium dodecyl sulfate, and shear operation, will make the relaxation unit (mesh) larger and lead to the left shift of the intersection of G′ and loss modulus (G″). In a PVA solution with a high concentration, multiple meshes of various sizes could be formed and thus generate multiple relaxation peaks. The large-sized meshes mainly contribute to the left shift of the intersection of G′ and G″, and the small-sized meshes contribute to the high plateau modulus. The results in this paper offer a new angle to analyze polymer solutions with strong intermolecular interaction.

Cryostructuring of Polymeric Systems: 67 Properties and Microstructure of Poly(Vinyl Alcohol) Cryogels Formed in the Presence of Phenol or Bis-Phenols Introduced into the Aqueous Polymeric Solutions Prior to Their Freeze–Thaw Processing

“…As it was pointed out in the “Introduction”, various phenolic compounds are capable of H-bonding with the OH-groups of PVA macromolecules [ 86 , 87 , 88 ]. For this reason, already at the stage of preparation of the gel-forming polymer solutions that contained phenolic additives and were intended for the fabrication of the respective PVACGs, similar non-covalent interactions could affect the physico-chemical characteristics of such solutions and, as a consequence, influence the properties of the resultant cryogels.…”

“…These examples evidently testify the need to know how additives of various chemical structure are able to interact with the PVA chains, to influence the cryotropic gel formation of this polymer, and, as a consequence, to affect the release behavior of substances entrapped in the cryogel bulk. The answer for these questions was the goal of the present study, where phenolic compounds, namely, o -, m -, and p -bis-phenols, as well as phenol itself, were used as water-soluble additives potentially capable of H-bonding with the OH-groups belonging to the PVA macromolecules [ 86 , 87 , 88 ]. It was also of interest to elucidate the effects of the interposition of hydroxyls in the molecules of bis-phenols in terms of their influence on the PVA cryotropic gel formation and the release of solutes from the respective PVACGs.…”

A biodegradable PVA coating constructed on the surface of the implant for preventing bacterial colonization and biofilm formation

“…Notably, the 15% PVA and 20% PVA groups exhibited only sporadic red fluorescence, indicating a significant reduction in bacterial presence on the titanium plate surface. We attribute this phenomenon to the hydrogen bonds and van der Waals forces between molecules in high concentration PVA solutions, which form tiny and dense pore structures [45]. This makes it difficult for bacteria to penetrate the PVA coating, proliferate and form a biofilm on the surface of the titanium plate [46].…”