Synthesis and characterization of functional thermoresponsive photoactive copolymers and study of their thermal and photoluminescence properties

ABSTRACT

Poly(N-isopropyl acrylamide-co-disperse yellow 7 methacrylate) (PNIPAM) copolymers were synthesized by radical polymerization of N-isopropyl acrylamide with disperse yellow 7 methacrylate using 2,2^/-Azo-bis-isobutyronitrile (AIBN) as an initiator. N-isopropyl acrylamide is a thermoresponsive monomer, and disperse yellow 7 methacrylate is a photoactive monomer. The synthesized photoactive and thermoresponsive copolymers were characterized by FTIR, NMR, and UV-Vis spectrophotometer with a temperature variation. A proton NMR signal at 8.16 ppm is observed for aromatic protons surrounded by an azo (-N=N-) group. The peak that appeared at 4.0 ppm is due to the CH-CONH group. The amide group proton of CONH appeared at 8.16 ppm. The molecular weights of homopolymers (like PNIPAM and PDY7MA) and their copolymers (PNIPDY) were observed to be 10⁴ and 10³ Da, respectively. The optical band gaps for synthesized copolymers, PNIPDY-1B, PNIPDY-2B, and PNIPDY-3B, are 2.98 eV, 2.95 eV, and 2.91 eV, respectively. The multiple emission spectra were observed at 407 nm, 428 nm, and 460 nm for the excitation energy of 365 nm due to the n-π* and π-π* transitions of the azobenzene chromophore. Thermal properties were also studied using TGA analysis. Stimuli-responsive polymers are widely used in optoelectronics and photonics, such as optical switching, optical information storage devices, liquid crystal display technology, and diffractive optical elements.

GRAPHICAL ABSTRACT

KEYWORDS:

• Photoactive polymers
• poly(n-isopropyl acrylamide)
• thermoresponsive polymers

Acknowledgments

The authors gratefully acknowledge the motivation and support of the Director, DMSRDE, Kanpur to pursue this research work and provide different characterization facilities. The authors also acknowledge Dr. A.K. Gupta, Sci ‘G’ DRDE, Gwalior to provide UV-vis and Elemental analysis facility.

Disclosure statement

There is no conflicts of interest between authors.

Additional information

Notes on contributors

Km. Meenu

Dr. Km. Meenu received her MSc (Chemistry) from CCS University, Meerut and Ph.D. (Chemistry) from the Department of Chemical Sciences, Bundelkhand University, Jhansi, India. Her Ph.D. is on the synthesis and characterization of functional chiral and photoactive polymers and copolymers. During the Ph.D. degree, she was a junior research fellow in Defence Materials and Stores Research and Development Establishment (DMSRDE), DRDO, Kanpur (2012 to 2017). Then she joined as a project research fellow (2017 to 2019) at Jiwaji University, Gwalior on the decontamination of chemical warfare agent and their simulants using zeolites. After that, she joined as a Research Associate (RA) in DRDE, Gwalior, and worked on the topic of decontamination of chemical warfare agent and their simulants. She is the inventor of 1 patent and has a total of 10 publications in reputed Journals/Conference Proceedings. She was the recipient of the technology group award for process optimization and technology transfer of 2-DG (2-Deoxy-D-Glucose) as a repurposed drug for Coronavirus in 2020.

Dibyendu S. Bag

Dr. Dibyendu Sekhar Bag is a Scientist of Polymer Materials and Technologies at Defence Materials and Stores Research and Development Establishment (DMSRDE), DRDO, Kanpur since 2000. He obtained his M. Sc. (Chemistry) and Ph.D. (Polymer Materials) degree-both from IIT, Kharagpur (1990-1996). Subsequently, after receiving his Ph.D. degree, he joined Ahmedabad Textile Industry’s Research Association (ATIRA) as a Senior Scientific Officer and worked for 2 years (1996-1998) on the development of Textile Chemicals/Polymers. Later he was an Assistant Professor for 2 years (1998-2000) in the Department of Polymer Engineering, Birla Institute of Technology, Mesra, Ranchi. He was also a visiting scientist of DRDO at Pennsylvania State University, USA in 2002. Dr. Bag has successfully executed various Defence R& D programs/projects and contributed to several defence systems and aircraft including LCA (Tejas). He is also associated with several collaborative research projects with Academic Institutes and leading several developmental activities with different industries. He is the recipient of a few awards including the “National Award for Technology Innovation” in 2020. He is the inventor of 10 patents and has a total of 190 publications in Reputed Journals/Technical Reports/Conference Proceedings. In addition, he is a lead contributor to a few invited book chapters in reputed edited books including in Encyclopedia of Chemical Technology. He has two co-edited books on his credit. He is the author of an International Book: “Principles of Polymers-An Advanced Book”. He is also an Editor of the Journal of Polymer Materials International Journal.