Preparation of Poly (N-Isopropylacrylamide) -Poly (2-Ethyl-2-Oxazoline) and Their Self-Assembly Properties with Dicarboxylic Acid

Abstract

This study reports the synthesis of copolymers that contain thermally responsive polymers, namely poly(N-isopropylacrylamide) (PNIPAM) and poly(2-ethyl-2-oxazoline) (PEOX), as well as biodegradable side groups that are water-soluble and capable of hydrogen bonding. The assay aims to produce heat-responsive PNIPAM and PEOX polymers with di-carboxylic acid (DCA) controlled structuring of the resulting pH-sensitive nano-structured polymers. These will be used as a template in the synthesis of inorganic materials. The study demonstrated the impact of pH, salt concentration, and temperature on the polymer/DCA. This fragment describes the functional groups of the thermosensitive polymers PNIPAM and PEOX. These polymers have carboxylic acid functional groups at both ends, are water soluble, and are capable of hydrogen bonding. The structure of these polymers can be recognized with small molecules of DCA in an aqueous solution at different pH, salt concentrations, and temperatures with H-bonds. Additionally, these polymers can be used as templates to synthesize hollow silica polymers. The synthesized monomers and polymers were structurally characterized using Fourier transform infrared spectrophotometer (FT-IR). The resulting structured polymers were identified by scanning electron microscopy and atomic force microscopy (SEM, AFM). UV-VIS spectrophotometer and Differential Scanning Calorimetry (DSC) were used to determine the Lower Critical Solution temperature of the polymers.

Keywords

• Self-organization
• pH-sensitivity
• nano-structured material
• template

References

1. 1. Pino-Ramos VH, Ramos-Ballesteros A, López-Saucedo F, López-Barriguete JE, Varca GHC, Bucio E. Radiation grafting for the functionalization and development of smart polymeric materials. In: Applications of Radiation Chemistry in the Fields of Industry, Biotechnology and Environment. Springer; 2017. p. 67–94.
2. 2. Wei M, Gao Y, Li X, Serpe MJ. Stimuli-responsive polymers and their applications. Polym Chem. 2017;8(1):127–43. Available from: URL
3. 3. Karimi M, Sahandi Zangabad P, Ghasemi A, Amiri M, Bahrami M, Malekzad H, et al. Temperature-responsive smart nanocarriers for delivery of therapeutic agents: applications and recent advances. ACS Appl Mater Interfaces. 2016;8(33):21107–33. Available from: URL 4. Li J, Kikuchi S, Sato S ichiro, Chen Y, Xu L, Song B, et al. Core-First Synthesis and Thermoresponsive Property of Three-, Four-, and Six-Arm Star-Shaped Poly (N, N-diethylacrylamide) s and Their Block Copolymers with Poly (N, N-dimethylacrylamide). Macromolecules. 2019;52(19):7207–17. Available from: URL
4. 5. Al-Zaidi AT, Al-Dokheily ME, Al-Atabi SH. Low critical solution temperatures and water swelling ratios of some new PNIPAAm copolymers synthesized by free radical polymerization. In: AIP Conference Proceedings. AIP Publishing LLC; 2020. p. 20176.
5. 6. Tseng W, Fang T, Chen C, Hsieh Y, Lai W. Upper Critical Solution Temperature‐Type Thermal Response of Soluble Multi‐l‐Arginyl‐Poly‐l‐Aspartic Acid (cyanophycin) Conjugated with Maltodextrin. J Polym Sci A Polym Chem. 2019;57(19):2048–55. Available from: URL
6. 7. Pasparakis G, Tsitsilianis C. LCST polymers: Thermoresponsive nanostructured assemblies towards bioapplications. Polymer, 2020; 211: 123146. Available from: URL
7. 8. Marsili L, Dal Bo M, Berti F, Toffoli G. Chitosan-Based Biocompatible Copolymers for Thermoresponsive Drug Delivery Systems: On the Development of a Standardization System. Pharmaceutics. 2021; 13(11): 1876. Available from: URL
8. 9. Kocak G, Tuncer C, Bütün V. Stimuli-Responsive Polymers Providing New Opportunities for Various Applications. Hacettepe J. Biol. & Chem., 2020; 48(5): 527-574. Available from: URL 10. Konefał R, Spěváček J, Černoch P. Thermoresponsive poly (2-oxazoline) homopolymers and copolymers in aqueous solutions studied by NMR spectroscopy and dynamic light scattering. Eur Polym J. 2018; 100: 241–52. Available from: URL

9. 11. Tang Q, Qian S, Chen W, Song X, Huang J. Preparation and characterization of temperature-responsive Ca–alginate/poly(N-isopropylacrylamide) hydrogel. Polym Int, 2023; 72: 252-262. Available from: URL
10. 12. Lusina A, Nazim T, Cegłowski M. Poly(2-oxazoline)s as Stimuli-Responsive Materials for Biomedical Applications: Recent Developments of Polish Scientists. Polymers. 2022; 14(19):4176. Available from: URL
11. 13. Mizusaki M, Endo T, Nakahata R, Morishima Y, Yusa S ichi. pH-induced association and dissociation of intermolecular complexes formed by hydrogen bonding between diblock copolymers. Polymers (Basel). 2017;9(8):367. Available from: URL
12. 14. Zhu YG, Wang Y, Shi Y, Wong JI, Yang HY. CoO nanoflowers woven by CNT network for high energy density flexible micro-supercapacitor. Nano Energy. 2014;3:46–54. Available from: URL
13. 15. Altıntaş Z, Adatoz EB, Ijaz A, Miko A, Demirel AL. Self-assembled poly (2-ethyl-2-oxazoline)/malonic acid hollow fibers in aqueous solutions. Eur Polym J. 2019;120:109222. Available from: URL 16. Kocak G, Tuncer C, Bütün V. pH-Responsive polymers. Polym Chem. 2017;8(1):144–76. Available from: URL
14. 17. Hendessi S, Güner PT, Miko A, Demirel AL. Hydrogen bonded multilayers of poly (2-ethyl-2-oxazoline) stabilized silver nanoparticles and tannic acid. Eur Polym J. 2017;88:666–78. Available from: URL
15. 18. Oleszko-Torbus N, Utrata-Wesołek A, Bochenek M, Lipowska-Kur D, Dworak A, Wałach W. Thermal and crystalline properties of poly (2-oxazoline)s. Polym Chem. 2020;11(1):15–33. Available from: URL 19. Ohnsorg ML, Ting JM, Jones SD, Jung S, Bates FS, Reineke TM. Tuning PNIPAm self-assembly and thermoresponse: roles of hydrophobic end-groups and hydrophilic comonomer. Polym Chem. 2019;10(25):3469–79. Available from: URL
16. 20. Gandhi A, Paul A, Sen SO, Sen KK. Studies on thermoresponsive polymers: Phase behaviour, drug delivery and biomedical applications. Asian J Pharm Sci. 2015;10(2):99–107. Available from: URL
17. 21. Adams N, Schubert US. Poly (2-oxazolines) in biological and biomedical application contexts. Adv Drug Deliv Rev. 2007;59(15):1504–20. Available from: URL
18. 22. Gaertner FC, Luxenhofer R, Blechert B, Jordan R, Essler M. Synthesis, biodistribution and excretion of radiolabeled poly (2-alkyl-2-oxazoline) s. Journal of Controlled Release. 2007;119(3):291–300. Available from: URL
19. 23. Dutta K, De S. Smart responsive materials for water purification: an overview. J Mater Chem A Mater. 2017;5(42):22095–112. Available from: URL
20. 24. Zou H, Wu Q, Li Q, Wang C, Zhou L, Hou XH, et al. Thermo-and redox-responsive dumbbell-shaped copolymers: from structure design to the LCST–UCST transition. Polym Chem. 2020;11(4):830–42. Available from: URL
21. 25. Chen JJ, Ahmad AL, Ooi BS. Poly (N-isopropylacrylamide-co-acrylic acid) hydrogels for copper ion adsorption: Equilibrium isotherms, kinetic and thermodynamic studies. J Environ Chem Eng. 2013;1(3):339–48. Available from: URL
22. 26. Wang J, Sutti A, Lin T, Wang X. Thermo-responsive PNIPAM hydrogel nanofibres photocrosslinked by azido-POSS. In: Fiber Society Spring 2013 Technical Conference. Fiber Society; 2013. Available from: URL
23. 27. Li G, Song S, Zhang T, Qi M, Liu J. pH-sensitive polyelectrolyte complex micelles assembled from CS-g-PNIPAM and ALG-gP (NIPAM-co-NVP) for drug delivery. Int J Biol Macromol. 2013;62:203–10. Available from: URL
24. 28. Lai H, Wang Z, Wu P. Structural evolution in a biphasic system: poly (N-isopropylacrylamide) transfer from water to hydrophobic ionic liquid. RSC Adv. 2012;2(31):11850–7. Available from: URL
25. 29. Saad A, Mills R, Wan H, Mottaleb MA, Ormsbee L, Bhattacharyya D. Thermo-responsive adsorption-desorption of perfluoroorganics from water using PNIPAm hydrogels and pore functionalized membranes. J Memb Sci. 2020;599:117821. Available from: URL
26. 30. Rusen L, Dinca V, Mustaciosu C, Icriverzi M, Sima LE, Bonciu A, et al. Smart Thermoresponsive Surfaces Based on pNIPAm Coatings and Laser Method for Biological Applications. Modern Technologies for Creating the Thin-film Systems and Coatings. 2017;10. Available from: URL
27. 31. Mourdikoudis S, Pallares RM, Thanh NTK. Characterization techniques for nanoparticles: comparison and complementarity upon studying nanoparticle properties. Nanoscale. 2018;10(27):12871–934. Available from: URL
28. 32. Niranjanmurthi L, Park C, Lim KT. Synthesis and characterization of graphene oxide/poly (2-ethyl-2-oxazoline) composites. Molecular Crystals and Liquid Crystals. 2012;564(1):206–12. Available from: URL 33. Minkova LI, Miteva T, Sek D, Kaczmarczyk B, Magagnini PL, Paci M, et al. Reactive blending of a functionalized polyethylene with a semiflexible liquid crystalline copolyester. J Appl Polym Sci. 1996;62(10):1613–25. Available from: URL
29. 34. Kuo SW. Hydrogen bonding in polymeric materials. John Wiley & Sons; 2018. Available from: URL