Colorless and transparent semi‐alicyclic polyimide films with intrinsic flame retardancy based on alicyclic dianhydrides and aromatic phosphorous‐containing diamine: Preparation and properties

Abstract

Semi‐alicyclic colorless and transparent polyimide (PI) films with intrinsically flame‐retardant features, excellent optical transparency, and good thermal stability have been designed and successfully prepared. For this target, an aromatic diamine with lateral diphenylphosphine oxide substituent, 2,5‐bis[(4‐aminophenoxy)phenyl]diphenylphosphine oxide (BADPO) was polymerized with two alicyclic dianhydrides, including hydrogenated pyromellitic dianhydride (HPMDA) and hydrogenated 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (HBPDA), respectively, via a one‐step high‐temperature polycondensation procedure to afford two PIs, PI‐a (HPMDA‐BADPO), and PI‐b (HBPDA‐BADPO). The derived PI films maintained the intrinsic good properties for semi‐alicyclic PI films, including excellent optical transparency in the ultraviolet–visible light region with the cutoff wavelength (λcut) around 322 nm and optical transmittance at the wavelength of 450 nm (T450) higher than 83.0%. In addition, the PI films exhibited good thermal stability with the 5% weight loss temperatures (T5%) higher than 460.0°C and glass transition temperatures (Tg) higher than 235.0°C. More importantly, the developed PI films exhibited intrinsic flame retardancy with the limited oxygen indices (LOI) of 41.1% for PI‐a and 28.8% for PI‐b. What is more, the PI films showed the flame retardancy class of UL94 VTM‐0 and low thermal energy and smoke release during combustion.

New polyimides containing methyl benzamidobenzoate or dimethyl benzamidoisophthalate as bulky pendant groups. Effects on solubility, thermal and gas transport properties

“…10 Many efforts have been made to improve the solubility of PIs, focusing on modifying the structural characteristics of the monomers to reduce the interactions between the polymer chains. Some feasible approaches such as the incorporation of bulky groups in the main or side chain, [11][12][13][14] flexible linkages, [15][16][17][18] alicyclic units, [19][20][21] fluorine groups, 3,22,23 alkyl/aryl silane fragments (-ArSi [R 1 R 2 ]Ar-), [24][25][26][27][28] among others, [29][30][31][32] have been used to prepare soluble PIs.…”

Preparation and characterization of colorless and transparent semi‐alicyclic fluoro‐containing polyimide nanocomposite films with enhanced high‐temperature dimensional stability via incorporation of colloidal silica nanofillers

“…1 Among the various high-tech polymer films, colorless and transparent polyimide (CPI) films definitely rank the top level due to the excellent combined thermal resistance, optical properties, mechanical and dielectric properties. [2][3][4][5] Various high-performance CPI films, including the fluoro-containing ones, [6][7][8] semi-alicyclic ones, [9][10][11] and the hybrid ones simultaneously containing fluoro and alicyclic 12,13 units have been developed in the past decades. The derived CPI films usually exhibited good comprehensive properties; however, some property defects relative to the standard wholly aromatic PI films, such as the commercially available Kapton ® (trademark of DuPont, USA) series of films derived from pyromellitic dianhydride (PMDA) and 4,4 0 -oxydianiline (ODA) (PI PMDA-ODA ), have to be remedied in practical applications.…”

The Synergistic Effect of Triazine and Phosphaphenanthrene Units on the Physico-Chemical Behavior of Polyimides

“…The thermal stability endowed by the incorporation of phosphinate linkage [–O–(O=)P–O–C] into a cyclic form is higher than that of a phosphonate type [–O–(O=)P–O–] based polymer [ 31 ]. Thus, recently, several phosphorus-containing polyimides have been reported with improved physico-chemical properties through monomer functionalization with flexible units [ 16 , 32 , 33 , 34 ] or by using copolymerization techniques [ 35 , 36 ]. Particular interest has been devoted to the development of phosphorus-based polyimides for use as proton exchange membranes [ 37 , 38 ], or polyimide composites with pristine or functionalized polyhedral oligomeric silsesquioxane for atomic oxygen resistance applications [ 39 , 40 , 41 ].…”