Preparation and performance testing of novel bendable optically transparent fluorinated hyperbranched linear long chain segment poly(amide-imide) films

• Published in: Polymer chemistry 2024-02, Vol.15 (9), p.93-914
• Main Authors: Sun, Ze-Bang, Yang, Wen, Zhang, Xiao-Sa, Zhu, Xiao-Yu, Luan, Jian, Li, Wen-Ze, Liu, Yu
• Format: Article
• Language: English
• Subjects: Birefringence; Chromaticity; Copolymerization; Diamines; Fluorination; Monomers; Near infrared radiation; NMR; NMR spectroscopy; Nuclear magnetic resonance; Optical properties; Polyethylene terephthalate; Polymers; Polymethyl methacrylate; Refractivity; Segments; Tensile strength; Thermal stability
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/d3py01306e

In the present work, we prepared a fluorinated triacid monomer from a triamino monomer (TFAPOB) and trimellitic anhydride using the thermal snap ring method. Subsequently, a series of fluorinated hyperbranched linear long chain segment poly(amide-imide)s (PAIs) were prepared by reacting this triacid monomer with four linear diamine monomers, respectively, which contained pendant units. The degree of branching of each of the four polymers was calculated using 1 H nuclear magnetic resonance (NMR) spectroscopy (51%-54%). The prepared polymers exhibited good solubility and film-forming properties in common organic solvents and were thermally stable ( T 10% : 562-602 °C, T g s: 228-237 °C). Subsequently, the mechanical and photovoltaic properties of the polymers were investigated. The tensile strength of the films was in the range of 85.5-100.7 MPa, the elongation at break was in the range of 7.0-8.2%, and the transparent PAI films had low dielectric constants (2.10-2.48). In terms of optical properties, the birefringence values of the PAI films were in the range of 0.0010-0.0018 (650 nm), and the refractive index could be adjusted by means of copolymerization. The prepared PAI films have good transmittance (450 nm: 86%-88%; 550 nm: 89%-91%; 800 nm: 91%-93%), cut-off wavelengths in the range of 332-353 nm, and a small absorption range in the near infrared region (1300 and 1560 nm). In addition, the PAI films are very light in color, especially the PAI-3 films (CIE 1931 X : 0.34806; Y : 0.33371; yellowness (YI): −6.33; whiteness (H): 90.63, whiteness (R): 88.47), which have chromaticity parameters that are similar to those of commercially available transparent films such as polymethyl methacrylate (PMMA) and poly(ethylene terephthalate) (PET), and which are also characterized by a high degree of thermal stability. A series of fluorinated hyperbranched linear long-chain segment poly(amide-imide)s were prepared. Subsequently, a detailed comparative study of the optical properties of the hyperbranched PAI films with those of commercial films was carried out.