Structural and optical characteristics of poly(vinyl alcohol)/carboxymethyl cellulose/ curcumin nanocomposites

Abstract

ABSTRACT. Curcumin nanoparticles (CurNP’s) were successfully synthesized, characterized, and used as a cross-linking dopant of polyvinyl alcohol/ sodium carboxymethyl cellulose (PVA/CMC) semi-natural polymer blend. Synthesized nanocomposite films of (PVA/CMC/CurNP’s) were characterized using Fourier transforms infrared FTIR spectroscopy and tested for their resistance of different bacterial grams. Obtained data shows that studied PVA polymerized and cross-linked with CMC as a result for hydrogen bonding between the carboxylic groups and with the non-substituted hydroxyl groups of the cellulose molecule. The optical energy gap was found to be sensitive for the CurNP’s doping level, and the indirect transition was dominant in the studied samples. The addition of CurNP’s appears to increase the activity index of all samples against both gram-negative and positive bacteria, and their activity increases with increasing dopant level until a specific optimal concentration.
 
 KEY WORDS: Curcumin nanoparticles, Semi-natural polymer blend, Antibacterial, FTIR, Optical energy gap
 
 Bull. Chem. Soc. Ethiop. 2021, 35(3), 615-624.
 DOI: https://dx.doi.org/10.4314/bcse.v35i3.12

Molecular structure and optical attributes of (Na-CMC/SA) natural polymer blend

“…Figure 4 exhibits the UV/Vis spectra of virgin polymers and polymeric blend film that lie inside the range of invisible UV region. The Na-CMC, SA, and Na-CMC/SA membranes have an absorption rate of 234, 227, and 227 nm, which potentially owing to the charge-relocate complexes' presence for the Na-CMC and polymer blend cases and the (-*) transition of the carbonyl groups (C=O) for SA case [7,13,16,[23][24][25][26]. 2:…”

“…(2) The power (m) indicates the transformation of the direct and indirect at m = 0.5 and 2, respectively. Furthermore, the bandgap can be determined as follows [13,[25][26][27]:…”

“…The computed (HOMO/LUMO) orbitals of the virgin samples secured using the Gaussian program in addition to those reported in Table 3 were demonstrated in Figure 6. The (LUMO) of Na-CMC is situated in the carboxylate group (-COO) however the (HOMO/LUMO) orbitals of SA are located at (-COONa) [26,27,30]. As a result, the carboxylate group served as a crucial eventful site for virgin polymers.…”

“…Figure 5 showed the optical properties studies as (a) absorption coefficients (α), (b and c) direct and indirect band gap (Eg d and Ed in ), and (d) Urbach energy (EU) and collected in Table2:(1) The absorption coefficients (α) can be estimated by Beer-Lambert's formula[25][26][27]:…”