Synthesis of fluorinated polybenzoxazoles with low dielectric constants

Abstract

Two fluorinated aromatic bis(o-aminophenol)s, 1,1bis(3 0 -amino-4 0 -hydroxyphenyl)-1-(3 0 -trifluoromethylphenyl)-2,2, 2-trifluoroethane (6FAP) and 1,1-bis(3 0 -amino-4 0 -hydroxyphenyl)-1-(3 0 ,5 0 -ditrifluoromethylphenyl)-2,2,2-trifluoroethane (9FAP) were synthesized, which were allowed to polycondense with aromatic diacyl chlorides to afford the fluorinated aromatic polybenzoxazoles (PBOs) via a conventional two-step procedure in which the low-temperature solution polycondensation process was first performed to yield poly(o-hydroxyamide)s (PHAs) followed by the thermal cyclodehydration to give the PBOs. Experimental results indicated that the PHAs had inherent viscosities in the range of 0.29-0.68 dL/g, showing excellent solubility in organic solvents. The PHAs could be thermally cyclodehydrated into the corresponding PBOs at 260-370 C. The obtained PBOs exhibited enhanced glass-transition temperature but decreased solubility with respect to the PHAs. The PBOs showed glasstransition temperatures in the range of 315-337 C and excellent thermal stabilities with 5% original weight-loss temperatures (T 5 ) of >513 C. Additionally, the PBO films had average refractive index of 1.5298-1.5656, birefringence of 0.0051-0.0092, and low dielectric constants of 2.57-2.70. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: [4668][4669][4670][4671][4672][4673][4674][4675][4676][4677][4678][4679][4680] 2010 Materials 3 0 -Trifluoromethyl-2,2,2-trifluoroacetophenone (6FK) and 3 0 ,5 0ditrifluoromethyl-2,2,2-trifluoroacetophenone (9FK) were synthesized in our laboratory according to the previously reported

Factors influencing thermal, mechanical, optical, and adhesive properties of segmented poly(imide siloxane) copolymers films

“…Compared with kapton-IF70 film (the dielectric constant is 3.6 at 10.1 GHz), all these PI films had lower dielectric constants (2.60 to 2.93) and dielectric losses (3.9 × 10 −3 to 10.2 × 10 −3 ). 30 Silicon atoms are larger than carbon atoms, Si O bond is more flexible than C C bond, and flexibility of aliphatic siloxane chain is higher than that of the general polyimide chain. The molecular polarity of polymer, 10 the volume of molecular chains, 11 and the arrangements between the molecular chains affect the dielectric constant of polymer.…”

Hyperbranched polybenzoxazoles incorporated polybenzoxazoles for high‐performance and low‐Kmaterials

“…13 They have also achieved a k value of 2.57 at 1 MHz in fluorinated PBO. 14 However, the simultaneously increased chain flexibility in such polymers could result in increased CTE, and the synthesis of highly fluorinated monomers for polymerization was usually costly and complicated. The k values of polymers could also be reduced by the creation of nanoscale or microscale pores in matrix through hard or soft template methods.…”

Synthesis of hyperbranched polybenzoxazoles and their molecular composites with epoxy resins

“…[7][8][9] It is the rigid-rod polymer chains that endow PBO with these super properties, however, it inevitably makes PBO incompliant with common processing, because PBO can neither be dissolved in common solvents nor melt before decomposition. For example, it is shown that the incorporation of fluorine atoms in aromatic polymers, such as PI, could improve its solubility, 12 while the fluorinated PBO was not always soluble in organic solvent, 13 which may be because of the higher interchain packing ability of benzoxazole groups as compared to imide rings, flexible bonds were further needed to reduce the chain rigidity. 7 Moreover, despite it is recognized that PBO is an ideal reinforcing agent for polymer composites, the insoluble feature of PBO makes it only possible to reinforce polymer matrix in the form of fibers, while unable to directly incorporate the rigid-rod chains into polymers on molecular level.…”