Enhancement of Ultraviolet Light Resistance of Colorless and Transparent Semi-Alicyclic Polyimide Nanocomposite Films via the Incorporation of Hindered Amine Light Stabilizers for Potential Applications in Flexible Optoelectronics

Abstract

Optically transparent polymer films with excellent thermal and ultraviolet (UV) resistance have been highly desired in advanced optoelectronic fields, such as flexible substrates for photovoltaic devices. Colorless and transparent polyimide (CPI) films simultaneously possess the good thermal stability and optical transparency. However, conventional CPI films usually suffered from the UV exposure and have to face the deterioration of optical properties during the long-term service in UV environments. In the current work, the commercially available hindered amine light stabilizers (HALS) were tried to be incorporated into the semi-alicyclic CPI matrix with the aim of enhancing the UV exposure stability. For this target, a CPI-0 film was first prepared from hydrogenated pyromellitic dianhydride (HPMDA) and 2,2′-dimethylbenzidine (DMBZ) via a one-step polycondensation procedure. Then, the commercially available HALS were incorporated into the CPI-0 (HPMDA-DMBZ) film matrix to afford four series of CPI/HALS composite films. Experimental results indicated that the Tinuvin® 791 HALS showed the best miscibility with the CPI-0 film matrix and the derived CPI-D series of composite films exhibited the best optical transmittances. The CPI-D nanocomposite films showed apparently enhanced UV exposure stability via incorporation of the 791 additives. For the pristine CPI-0 film, after the UV exposure for 6 h, the optical properties, including the transmittance at the wavelength of 350 nm (T350), lightness (L*), yellow indices (b*), and haze obviously deteriorated with the T350 values from 55.7% to 17.5%, the L* values from 95.12 to 91.38, the b* values from 3.38 to 21.95, and the haze values from 1.46% to 9.33%. However, for the CPI-D-10 film (791: CPI-0 = 1.0 wt%, weight percent), the optical parameters were highly maintained with the T350 values from 61.4% to 53.8%, the L* values from 95.46 to 95.36, the b* values from 1.84 to 1.51, and the haze values from 0.69% to 3.34% under the same UV aging conditions.

Structural Designs of Transparent Polyimide Films with Low Dielectric Properties and Low Water Absorption: A Review

“…CPIs are very important in various applications, such as optoelectronic devices, active-matrix organic light-emitting display devices (AMOLEDs), touch sensors, printed circuit boards (PCBs), thin-film transistors (TFTs), and solar cells [ 51 , 52 ]. Furthermore, the AMOLED displays of mobile electronic devices, such as smartphones and tablet PCs, are expected to be continuously improved in terms of visibility, durability, weight, and flexibility; consequently, CPIs have attracted significant amounts of academic and industrial research attention [ 53 , 54 ]. Recent research has demonstrated that adding specific structures to the main chain of PIs, such as fluorinated groups, alicyclic-group-containing monomers, noncoplanar structures, meta-substituted structures, or sulfones, can increase the transparency of PI films while lowering CTC formation [ 55 ].…”

“…Recent research has demonstrated that adding specific structures to the main chain of PIs, such as fluorinated groups, alicyclic-group-containing monomers, non-coplanar structures, meta-substituted structures, or sulfones, can increase the transparency of PI films while lowering CTC formation [55]. research attention [53,54]. Recent research has demonstrated that adding specific structures to the main chain of PIs, such as fluorinated groups, alicyclic-group-containing monomers, noncoplanar structures, meta-substituted structures, or sulfones, can increase the transparency of PI films while lowering CTC formation [55].…”

Preparation and Characterization of Light-Colored Polyimide Nanocomposite Films Derived from a Fluoro-Containing Semi-Alicyclic Polyimide Matrix and Colloidal Silica with Enhanced High-Temperature Dimensionally Stability

“…Among various CPI films, the ones based on the alicyclic dianhydrides and aromatic diamines, that is, the semi-alicyclic (or semi-aromatic) systems, have attracted great attention in the research and development of high-performance polymers for optoelectronic applications due to the excellent combined thermal, optical, mechanical, and dielectric properties and the relatively low cost at the same time [ 13 , 14 , 15 , 16 ]. Various methodologies based on the molecular design of the functional alicyclic dianhydride or the aromatic diamine monomers have been proposed and carried out to reduce the CTE values of the semi-alicyclic CPI films.…”

Preparation and Characterization of Light-Colored Polyimide Nanocomposite Films Derived from Fluoro- Containing Semi-Alicyclic Polyimide Matrix and Colloidal Silica with Enhanced High-Temperature Dimensionally Stability

“…Among various CPI films, the ones based on the alicyclic dianhydrides and aromatic diamines, that is the semi-alicyclic (or semi-aromatic) systems have attracted great attentions in the research and development of high-performance polymers for optoelectronic applications due to the excellent combined thermal, optical, mechanical and dielectric properties and the relatively low cost at the same time [13][14][15][16]. Various methodologies based on the molecular design of the functional alicyclic dianhydride or the aromatic diamine monomers have been proposed and carried out to reduce the CTE values of the semi-alicyclic CPI films.…”