Effect of MWCNTs Functionalization on Thermal, Electrical, and Ammonia-Sensing Properties of MWCNTs/PMMA and PHB/MWCNTs/PMMA Thin Films Nanocomposites

Raina Aman Qazi; Rozina Khattak; Luqman Ali Shah; Rizwan Ullah; Muhammad Sufaid Khan; Muhammad Sadiq; Mahmoud M Hessien; Zeinhom M El-Bahy

doi:10.3390/nano11102625

Effect of MWCNTs Functionalization on Thermal, Electrical, and Ammonia-Sensing Properties of MWCNTs/PMMA and PHB/MWCNTs/PMMA Thin Films Nanocomposites

Nanomaterials (Basel). 2021 Oct 6;11(10):2625. doi: 10.3390/nano11102625.

Authors

Raina Aman Qazi^{1

2}, Rozina Khattak², Luqman Ali Shah¹, Rizwan Ullah¹, Muhammad Sufaid Khan³, Muhammad Sadiq⁴, Mahmoud M Hessien⁵, Zeinhom M El-Bahy⁶

Affiliations

¹ National Centre of Excellence in Physical Chemistry, Polymer Laboratory, University of Peshawar, Peshawar 25120, Pakistan.
² Department of Chemistry, Shaheed Benazir Bhutto Women University, Peshawar 25000, Pakistan.
³ Department of Chemistry, University of Malakand, Chakdara 18800, Pakistan.
⁴ Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan.
⁵ Department of Chemistry, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia.
⁶ Department of Chemistry, Faculty of Science, Al-Azhar University, Nasr City, Cairo 11884, Egypt.

Abstract

Partially biodegradable polymer nanocomposites Poly(3-Hydroxybutyrate) (PHB)/MultiwalledCarbon Nanotubes (MWCNTs)/Poly(Methyl Methacrylate) (PMMA)and non-biodegradable nanocomposites (MWCNTs/PMMA) were synthesized, and their thermal, electrical, and ammonia-sensing properties were compared. MWCNTs were chemically modified to ensure effective dispersion in the polymeric matrix. Pristine MWCNTs (p-MWCNTs) were functionalized with -COOH (a-MWCNTs) and amine groups (f-MWCNTs). Then, PHB grafted multiwalled carbon nanotubes (g-MWNTs) were prepared by a 'grafting to' technique. The p-MWCNTs, a-MWCNTs, f-MWCNTs, and g-MWCNTs were incorporated into the PMMA matrix and PMMA/PHB blend system by solution mixing. The PHB/f-MWCNTs/PMMA blend system showed good thermal properties among all synthesized nanocomposites. Results from TGA and dTGA analysis for PHB/f-MWCNTs/PMMA showed delay in T₅ (about 127 °C), T₅₀ (up to 126 °C), and T_max (up to 65 °C) as compared to neat PMMA. Higher values of frequency capacitance were observed in nanocomposites containing f-MWCNTs and g-MWCNTs as compared to nanocomposites containing p-MWCNTs and a-MWCNTs. This may be attributed to their excellent interaction and good dispersion in the polymeric blend. Analysis of ammonia gas-sensing data showed that PHB/g-MWCNTs/PMMA nanocomposites exhibited good sensitivity (≈100%) and excellent repeatability with a constant response. The calculated limit of detection (LOD) is 0.129 ppm for PHB/g-MWCNTs/PMMA, while that of all other nanocomposites is above 40 ppm.

Keywords: ammonia sensors; electrical properties; multiwalled carbon nanotubes; nanocomposites; poly(3-hydroxybutyrate); poly(methyl methacrylate); thermal stability.