| Poly(ether ether ketone) (PEEK) is known as one of the high-performance semicrystalline engineering thermoplastics due to its unique properties such as acid-resistance, alkali-resistance, heat-resistance, size-accuracy, mechanical and electrical characteristics. However, there has been a continuous demand for high temperature materials for use in microelectronic devices, such as the substrate for printed wire boards, insulating materials as interlayer dielectrics and intermetal dielectrics. And it's difficult for PEEK to meet the continuous demand because PEEK possesses low Tg, high dielectric contant, and poor solubility.Bulky Adamantyl groups possessed non-plarity and high thermal stablilty, owning to its unique rigid, multicyclic cage structure. And thereby it was incorporated into polymer chains to improve the polymer's properties. Due to its rigid and bulky spheric structure restricting the mobility of polymer chains, the Tgs of polymers were dramatically increased. The crystallization of polymer was devastated and hence the polymer solubility was improved, affording the feasibility for processing the polymer with spining-on methods. And it was reported that the incorporation of adamantyl groups decreased the dielectric constant of the polymers because its non-polarity"diluted"the polarity of the polymers and its bulky volume increased the free volume of the polymers. So we attempted to incorporate adamantyl groups into PAEKs to improve its properties, such as Tg, solubility, dielectric constant and water absorption.In the paper, three kinds of bisphenol monomers containing adamantyl groups, (4-(1-adamantyl))phenyl hydroquinone (AdPhHQ), 4-(1-adamantyl)-1, 3-benzenediol (AdRES) and 4, 8-bis(1-adamantly)- 1, 5-dihydroxynaphthalene (AdNp) were synthesized via the Friedel-Crafts reaction. And structures of these monomers were confirmed by MS, FTIR, and 1H NMR.Three series of adamantyl-contained poly(aryl ether ketone)s (PAEKs) with high molecular weight had been successfully synthesized from the bisphenol monomers via nucleophilic aromatic substitution reaction: AdPh-PEEK (derived from AdPhHQ and hydroquinone(HQ) with a malor loading ratio of 1:3), AdRES-PEEKs (derived from AdRES and different bisphenol with a malor loading ratio of 1:1)and AdNp-PEEKs(derived from AdNp and different bisphenol with a malor loading ratio of 1:1), AdRES-CF3BEN-PEEKs(derived from AdRES and (3-trifluoromethyl)phenyl hydroquinone (CF3BEN) with varied malor loading ratio) and AdNp-CF3BEN-PEEKs(derived from AdNp and CF3BEN with varied malor loading ratio). And all the polymers were characterized by FTIR and 1H NMR to determine their structures.Owning to the incorporation of admantyl groups, all the PAEKs exhibited excellent solublilty in common organic solvents, such as CHCl3, THF and NMP, which afforded the feasibility for processing the polymers with spining-on methods. The incorporation of admantyl groups into the PAEKs also led to the dramatic increase of Tgs, because bulky adamantyl gourps would increase the rigidity of polymer chains and block the movement of segments. Copolymer AdPh-PEEK had a Tg of 171oC, which was an increase of 28oC compared to that of the commerical PEEK (143°C). The Tgs of AdNp-PEEKs were higher than that of corresponding Np-PEEKs(derived from 1,5-Dihydroxynaphthalene and different bisphenols with a malor loading ratio of 1:1) by 45oC, and the Tgs of AdNp-PEEKs were higher than that of corresponding AdRES-PEEKs by 25oC, which indicated that 4, 8-bis(1-adamantly)- 1, 5-naphthalene moieties would increase the Tgs of PAEKs more effectively than 4-(1-adamantyl)-1,3-benzene moieties. The Tgs of AdNp-CF3BEN-PEEKs and AdRES-CF3BEN-PEEKs would increase at linear with the increased loading ratio of adamantyl-contained bisphenols. If the molar loading ratio of adamantyl-contained bisphenols were increased by 25%, the Tgs of AdNp-CF3BEN-PEEKs and AdRES-CF3BEN-PEEKs would incease with 35oC and 25oC, respectively.The PAEKs containing adamantyl groups possessed good thermal stability. The PAEKs containing 4, 8-bis(1-adamantly)-1, 5-naphthalene moieties had a 5% weight losses above 490oC in N2, and that containing 4-(1-adamantyl)-1,3-benzene moieties had a 5% weight losses above 440oC in N2. It's also indicated that the thermal stability of 4, 8-bis(1-adamantly)-1, 5-naphthalene moieties was higher than that of 4-(1-adamantyl)-1,3-benzene moieties.Young's moduli of AdNp-CF3BEN-PEEKs and AdRES-CF3BEN-PEEKs were about 2.0 GPa, which were similar to that of commercial PEEK (2.21 GPa). Their tensile strength and elongation at break apparently decreased with the increased molar loading ratio of AdNp or AdRES, but they still exhibited enough strength.Owning to the hydrophobicity of adamantyl groups, all the adamantane-containing PAEKs had a low water absorbtion at 0.1-0.3%, which was lower than that of commercial PEEK (0.5%).Adamantyl groups decreased the dielectric constant and dielectric loss more effectively than (3-trifluoromethyl)phenyl groups, because adamantyl groups would increase the free volume of polymers at a larger scale. The dielectric constants of AdNp-CF3BEN-PEEKs and AdRES-CF3BEN-PEEKs (1MHz) had a decrease of 0.3-0.5 compared to that of PEEK. The dielectric loss factors (1MHz) for these polymers were between 5×10-3 and 8×10-3. Moreover, the dielectric constant and dielectric loss of these polymers decreased with increasing the molar content of the moieties containing admantyl groups.Based on the results of the paper, the PAEKs containing adamantyl groups held promise for insulated materials in microelectronic devices, which were worth being studied further in the future.
|
PDF Full Text Request