Flexible and highly fluorescent aromatic polyimide: design, synthesis, properties, and mechanism

Abstract

A flexible and highly fluorescent aromatic polyimide can be obtained by appropriate control of the intra-molecular charge-transfer effects between the diamine and dianhydride moieties.

Synthesis and properties of soluble aromatic polyimides from novel 4,5-diazafluorene-containing dianhydride

“…However, the dielectric constant of PI-4 had clearly dropping characteristic, which was rationalized by the space charge polarization. 10,34,38 The obtained polyimide lms exhibited low water absorption of 2.8-4.9% (Table 4). As expected, all the PI showed low water absorption, due to the proong effect of 4,5-diazouorene and triuoromethyl groups.…”

“…However, the rigid structure, strong inter-molecular interactions and charge transfer complex (CTC) of aromatic polyimides always lead to their poor solution processability and dark brownish colour, limiting their application in many areas. [8][9][10][11] Generally, polyimides are synthesized by the polycondensation of diamine and dianhydride. Many approaches focused on structure modication (novel diamine and dianhydride), such as introducing aliphatic chains, 12,13 exible linkage, [14][15][16] nonplanar structure, [17][18][19][20] bulky CF 3 groups [21][22][23] and ring-shaped structures, 24 are developed to overcome the traditional PIs' drawbacks mentioned above.…”

Reduced Coefficients of Linear Thermal Expansion of Colorless and Transparent Semi-Alicyclic Polyimide Films via Incorporation of Rigid-Rod Amide Moiety: Preparation and Properties

“…Thus, it is a changeling research topic to develop polymer optical films with both of excellent thermal stability and good optical transparency [5][6][7].In recent years, the research progress of colorless and transparent polyimide (CPI) films has attracted great attention in the research and development of high performance polymer optical films [8][9][10]. Based on the previous decades of research on the origination of coloration in traditional all-aromatic PI films, the researchers revealed many effective procedures to prohibit the formation of intra-or intermolecular charge transfer complexes (CTC) between the electron-donating diamine moiety and the electron-accepting dianhydride moiety so as to improve the optical transparency of the PI films [11][12][13]. At present, the effective means to develop CPI films mainly include introducing groups with high electronegativity characteristics, such as trifluoromethyl groups, sulphone groups, or substituents with non-conjugated characteristics, such as aliphatic or alicyclic groups, or groups with large molar volume-such as naphthalene, fluorene, or cardo groups-into the PI molecular chains [14][15][16][17][18][19][20].…”

Effect of mixed size particles reinforcing on the thermal and dynamic mechanical properties of Al2O3/PPS composites

“…where DH m is the melting enthalpy of the samples, DH o m is the melting enthalpy for 100% crystalline PPS polymer (DH o m 5 80 J/g), and x is the mass fraction for PPS in the VA/PPS composites [26][27][28][29].…”