Elfadl Azza Abou, Bashal Ali H, Habeeb Talaat H, Khalafalla Mohammed A H, Alkayal Nazeeha S, Khalil Khaled D
Department of Physics, Faculty of Science, Fayoum University, Fayoum 63514, Egypt.
Department of Chemistry, Faculty of Science, Taibah University, Yanbu 46423, Saudi Arabia.
Polymers (Basel). 2023 Oct 18;15(20):4132. doi: 10.3390/polym15204132.
Polymeric films made from chitosan (CS) doped with metal oxide (MO = cobalt (II) oxide and strontium oxide) nanoparticles at different concentrations (5, 10, 15, and 20% wt. MO/CS) were fabricated with the solution cast method. FTIR, SEM, and XRD spectra were used to study the structural features of those nanocomposite films. The FTIR spectra of chitosan showed the main characteristic peaks that are usually present, but they were shifted considerably by the chemical interaction with metal oxides. FTIR analysis of the hybrid chitosan-CoO nanocomposite exhibited notable peaks at 558 and 681 cm. Conversely, the FTIR analysis of the chitosan-SrO composite displayed peaks at 733.23 cm, 810.10 cm, and 856.39 cm, which can be attributed to the bending vibrations of Co-O and Sr-O bonds, respectively. In addition, the SEM graphs showed a noticeable morphological change on the surface of chitosan, which may be due to surface adsorption with metal oxide nanoparticles. The XRD pattern also revealed a clear change in the crystallinity of chitosan when it is in contact with metal oxide nanoparticles. The presence of characteristic signals for cobalt (Co) and strontium (Sr) are clearly shown in the EDX examinations, providing convincing evidence for their incorporation into the chitosan matrix. Moreover, the stability of the nanoparticle-chitosan coordinated bonding was verified from the accurate and broadly parametrized semi-empirical tight-binding quantum chemistry calculation. This leads to the determination of the structures' chemical hardness as estimated from the frontier's orbital calculations. We characterized the dielectric properties in terms of the real and imaginary dielectric permittivity as a function of frequency. Dielectric findings reveal the existence of extensive interactions of CoO and SrO, more pronounced for SrO, with the functional groups of CS through coordination bonding. This induces the charge transfer of the complexes between CoO and SrO and the CS chains and a decrease in the amount of the crystalline phase, as verified from the XRD patterns.
采用溶液浇铸法制备了由壳聚糖（CS）掺杂不同浓度（5%、10%、15%和20%重量比的金属氧化物/CS）的金属氧化物（MO = 氧化钴和氧化锶）纳米颗粒制成的聚合物薄膜。利用傅里叶变换红外光谱（FTIR）、扫描电子显微镜（SEM）和X射线衍射（XRD）光谱研究了这些纳米复合薄膜的结构特征。壳聚糖的FTIR光谱显示出通常存在的主要特征峰，但与金属氧化物的化学相互作用使其发生了显著位移。壳聚糖 - 氧化钴纳米复合材料的FTIR分析在558和681 cm处出现显著峰。相反，壳聚糖 - 氧化锶复合材料的FTIR分析在733.23 cm、810.10 cm和856.39 cm处出现峰，这分别可归因于Co - O和Sr - O键的弯曲振动。此外，SEM图显示壳聚糖表面有明显的形态变化，这可能是由于与金属氧化物纳米颗粒的表面吸附所致。XRD图谱还揭示了壳聚糖与金属氧化物纳米颗粒接触时结晶度的明显变化。能谱（EDX）检查清楚地显示了钴（Co）和锶（Sr）的特征信号，为它们掺入壳聚糖基质提供了令人信服的证据。此外，通过精确且广泛参数化的半经验紧束缚量子化学计算验证了纳米颗粒 - 壳聚糖配位键的稳定性。这导致了根据前沿轨道计算估计结构的化学硬度。我们根据实部和虚部介电常数随频率的变化来表征介电性能。介电研究结果表明，氧化钴和氧化锶通过配位键与壳聚糖的官能团存在广泛相互作用，氧化锶的这种作用更为明显。这导致了氧化钴和氧化锶与壳聚糖链之间配合物的电荷转移以及晶相量的减少，这从XRD图谱中得到了证实。
