Hydrogen-Bonding Assembly of Rigid-Rod Poly(p-sulfophenylene terephthalamide) and Flexible-Chain Poly(vinyl alcohol) for Transparent, Strong, and Tough Molecular Composites

Abstract

Molecular composites comprising poly(p-sulfophenylene terephthalamide) (sPPTA), a sulfonated polyaramid rigidrod polyelectrolyte, and flexible-chain poly(vinyl alcohol) (PVA) were prepared by a green and easy-to-scale-up water casting method. Influence of sPPTA on the microstructure and properties of the molecular composites was systematically investigated. Fourier transform infrared spectroscopy confirms the existence of hydrogen bonding between sPPTA and PVA. Wide-angle X-ray diffraction patterns do not show the characteristic of neat sPPTA crystalline aggregates in the composites even when the sPPTA content is as high as 33 wt %, suggesting that the strong interaction between sPPTA and PVA prevents the self-aggregation of sPPTA and leads to the formation of PVA/sPPTA complexes inside the composites. Transmission electron microscopy shows that sPPTA has good compatibility with PVA, and nanoscale fibril-like supramolecular assemblies dispersing uniformly in the composites become observable with the increase of sPPTA content. Moreover, the PVA/sPPTA complexes have a strong effect on the melt point, crystallinity, mechanical properties, and thermal stability of PVA. The PVA/sPPTA composites exhibit both high strength and high ductility. When the content of sPPTA is 5 wt %, the PVA/sPPTA composite exhibits the best mechanical properties, with a tensile strength of 169 ± 13 MPa, which is 54% higher than that of neat PVA (110 ± 10 MPa). Surprisingly, the reinforcement factor is even superior to that of multiwalled carbon nanotubes, vapor grown carbon fibers, and nanodiamonds previously reported for the reinforcement of PVA nanocomposites. Moreover, the PVA/sPPTA molecular composites have a relatively low modulus but a much larger elongation at break than prefabricated nanocomposites, showing good ductility. The strong and tough PVA/sPPTA molecular composites can be potentially used as high performance membranes or fibers in the future.

PVA/Carbon Dot Nanocomposite Hydrogels for Simple Introduction of Ag Nanoparticles with Enhanced Antibacterial Activity

“…Hence, in this experiment, the crystallinity of PVA and PVA/C‐dot hydrogels was estimated from the corresponding dried hydrogels instead. Figure b showed that the dried PVA and PVA/C‐dot hydrogels appeared the same characteristic peak of the crystal at 2 θ , 19.6° (strongest), 22.9°, and 40.8° corresponding to the (101), (200), and (102) planes of PVA crystals . The characteristic peaks of PVA crystal were nearly not changed in dried PVA/C‐dot hydrogel, indicating that C‐dot would not influence the crystal structure of PVA.…”

“…Because the bacterial infection is the main cause of wound infection, the antibacterial property is important for hydrogel used in medical field . Among various antimicrobial agents, silver is common and well‐studied due to its wide spread antimicrobial spectrum . Herein, taking the advantage of the reducibility of C‐dots, PVA/C‐dot hydrogel could adsorb Ag + and directly reduce Ag + to Ag nanoparticle without any other reducing agent, which was more convenient, economic, and green than other methods (introducing Ag nanoparticle in hydrogel).…”

Bioinspired strategy for tuning thermal stability of PVA via hydrogen-bond crosslink

“…Poly (vinyl alcohol) (PVA) is a commercially important semi-crystalline, hydrophilic polymers due to many outstanding features including good biocompatibility, biodegradability, gas barrier and water-solubility [1,2]. These properties make PVA extensively used as membranes for proton-exchange, permeability and separation, drug delivery carriers and flexible packaging films.…”

“…These properties make PVA extensively used as membranes for proton-exchange, permeability and separation, drug delivery carriers and flexible packaging films. [1][2][3] However, PVA is extremely thermally unstable especially during melt, which is primarily attributed to its strong intermolecular interactions through hydroxyl groups, making the melting point (T m ) of PVA very close to the initial degradation temperature (T i ) [3,4]. Thus, creating thermally stable PVA is highly attractive and significant for its melt processing.…”

Understanding the oxygen barrier property of highly transparent poly(lactic acid)/benzoxazine composite film by analyzing the UV‐shielding performance

“…Compared to the pristine PLA, BOZ10 shows less significant changes, but BOZ20 especially BOZ30 presents birefringent texture. These results demonstrate that, with introduction of 0–10.0 wt %, BOZ disperses uniformly and does not form birefringent in PLA matrix . However, when the weight contents of BOZ is more than 10.0 wt %, lots of amorphous BOZ monomers locate between the PLA chains and result in optically anisotropic domains in the PLA/BOZ composite film.…”