Fluorene‐rich high performance polyesters: Synthesis and characterization of 9,9‐fluorenylidene and 2,7‐fluorenylene‐based polyesters with excellent optical property

Abstract

Polyesters PEs containing high content of fluorene units in their backbones were synthesized from 9,9‐diarene‐substituted fluorene diols (1) and fluorene‐based diacid chlorides (2) by high temperature polycondensation at 185 °C in diphenyl ether. The molecular weights of the polyesters PE1‐PE5 were in a range of Mw 25,000–165,000. The polyesters displayed their high thermostability: the glass transition temperatures (Tg) by differential scanning calorimetry analysis ranged from 109 to 217 °C, while the 10% weight loss temperatures (Td10) measured by thermogravimetric analysis were over 400 °C in nitrogen and 395 °C in air. The polyesters had good solubility in most common organic solvents such as chloroform and toluene and gave tough, transparent and flexible cast films. The transmittance of the films was over 80% in the wavelength range from 450 to 700 nm in any PEs. The PEs exhibited high refractive index values around 1.65, while they had very low degree of birefringence. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2549–2556, 2008

9,9-Diarylfluorene-Based Poly(alkyl aryl ether)s: Synthesis and Property

“…These characteristic optical properties of the F-PEs come mainly from the cardo structure of the 9,9-diarylfluorene skeleton as well as the alkyl chains in the main chain. [1][2][3][4][5][6][7][8][9] In addition, the carbon filler (C 60 ) dispersing power of the F-PEs was confirmed and decreased with increase in length of the alkyl chain. Thus, the F-PEs can unambiguously be regarded as one of the potential polymer materials being used in a variety of fields including optical materials field.…”

“…The PET film had clear birefringence, as showed in Figure 8, while the films of 3a and 3d hardly showed the birefringence, in accordance with the reports on other polymers containing 9,9-diarylfluorenes. [1][2][3][4][5][6][7][8][9] Degree of retardation at 590 nm in 3d (thickness: 250 mm) was less than 3.28 nm in undrawn state, 53 and the birefringence value was remarkably low (less than 1:3 Â 10 À5 ). In the drawn film of 3d (drawn ratio is 2.0), the birefringence value was À8:9 Â 10 À4 , and the stress optical coefficient was very low (À0:15 GPa À1 ).…”

“…Such low birefringence should be attributed to the optical anisotropy decreasing effect of the cardo structure of the 9,9-diarylfluorene moiety placed in the main chain as mentioned. [1][2][3][4][5][6][7][8][9] The fluorene moiety and the two phenyl groups at the C9-position occupy different planes and are crossed at the precise angle that renders the structure most stable. Placing the aromatic rings on the different planes might disturb their one-directional folding, and thereby the optical anisotropy of the F-PEs disappears.…”

“…[1][2][3][4][5][6][7][8][9] Such optical property is caused by the presence of many aromatic rings in the 9,9-diarylfluorene moiety which occupy the different planes to disturb the interchromophore packing, effectively decreasing the optical anisotropy. Meanwhile, such polymers also display excellent filler-dispersing ability [10][11][12] in addition to their high thermal stability, [13][14][15][16] high solubility, [17][18][19] and so on.…”

Synthesis and Properties of Polysiloxanes Possessing 9,9-Diarylfluorene Structure in the Main Chain

“…[7][8][9][10][11][12] The optical properties were originated from many aromatic rings of the 9,9-diarylfluorene moiety as so-called ''cardo structure,'' in which each aromatic ring occupies different planes. In addition, such polymers exhibit other characteristic properties including fine dispersing ability for inorganic fillers, 13,14 good solubility toward organic solvents, 15 high thermal stability, [16][17][18][19] and so on. [20][21][22][23][24] Although several studies directed toward optical use of 9,9-diarylfluorene-based high performance polymers have been reported, the polymers often suffer from low heat-processability due to the high glass transition temperature (T g ).…”