Molecular mobility and morphology change of poly(vinyl alcohol) (PVA) film as induced by plasticizer glycerol

Abstract

The addition of small molecular plasticizer is an efficient strategy to increase the process ability and macroscopic performance of poly(vinyl alcohol) (PVA). However, how the plasticizer influences the chain dynamics and morphology deserves further investigation. In this work, the PVA film with varying glycerol addition levels was used as the model system. The increasing glycerol addition‐level results in the depression of the melting temperature and crystallization temperature, which in line with Flory's theory. The enhanced chain dynamics in the mobile domain was accessed by low‐field NMR, whereas that in the crystalline region remains constant. The domain size as well as the morphology of the mobile phase are accessed by 1H spin‐diffusion NMR. The results indicate the increasing dimensionality of the plasticized PVA film with increasing the addition level of glycerol, where the addition level below 25 wt% leads to the dimensionality of 1D, and higher than 25 wt% results in the dimensionality of 2D. Current results elucidate the critical role of the plasticizer in modulating the dynamics heterogeneity of the plasticized polymer film, which is closely related to the macroscopic performance of the products.

Synergistic Coassembly of Folic Acid-Based Supramolecular Polymer with a Covalent Polymer Toward Fabricating Functional Antibacterial Biomaterials

“…The depression of the T m indicates that the incorporation of folic acid reduced the ordered association and enhanced the chain dynamics of PVA, hence acting as a plasticizer to the PVA film. 37 It has been observed previously that the decrease in melting point of a crystalline polymer upon incorporation of a polymeric diluent can be correlated with the amount of interaction between the components. 38,39 Herein, the decrease in melting point (Figure 4e,f) in the coassembled FP gels (T m = 198.5 °C), compared to only PVA (T m = 216 °C), demonstrates the role of folic acid supramolecular polymers as a polymeric diluent, and their strong interactions with PVA.…”

“…The addition of folic acid (0.3% w / v ) resulted in a decrement of T m value to 198.5 °C (Figure f). The depression of the T m indicates that the incorporation of folic acid reduced the ordered association and enhanced the chain dynamics of PVA, hence acting as a plasticizer to the PVA film …”

Solid-State Utilization of Chitin to Construct Flexible Films with Enhanced Biocompatibility and Mechanical Performance

“…34−36 However, the strong hydrogen bonds between PVA molecules also make the decomposition temperature (220−250 °C) close to the melting point (226 °C), making it difficult to thermally process. 37,38 Our research group has realized the thermal processing of PVA via utilizing water and compounds containing amid or hydroxyl groups as the plasticizer, which destroyed the hydrogen boding and broadened the processing window of PVA. 39,40 Worku et al had prepared a PVA/chitin composite film with less than 10 wt % of chitin added, but the tensile strength of the composite film had been reduced from 23.40 to 18.85 MPa.…”

“…Poly­(vinyl alcohol) (PVA) is a polyhydric, highly polar, environmentally friendly polymer material with good biocompatibility and perfect film-forming performance, which can be produced on a large scale by nonpetroleum routes with low cost. , The polyhydroxy structure and adhesive bonding endow PVA with good interaction with chitin and further formability of the composites, exhibiting great potential in the biomedical application field . The abundant hydroxyl groups on the PVA molecular chain can form hydrogen bonds with chitin, which also helps to obtain composite materials with better performance. − However, the strong hydrogen bonds between PVA molecules also make the decomposition temperature (220–250 °C) close to the melting point (226 °C), making it difficult to thermally process. , Our research group has realized the thermal processing of PVA via utilizing water and compounds containing amid or hydroxyl groups as the plasticizer, which destroyed the hydrogen boding and broadened the processing window of PVA. , Worku et al had prepared a PVA/chitin composite film with less than 10 wt % of chitin added, but the tensile strength of the composite film had been reduced from 23.40 to 18.85 MPa . Therefore, there is still a big challenge with facile and scalable preparation of functional polymer-based composites with uniform dispersion of nanomicro fillers because of the limited pulverization mode and production efficiency of the traditional blending methods, such as ball milling, especially under the condition of high filler concentration.…”