Polymer CommunicationSynthesis and characterization of new polyamide-imides containing pendent adamantyl groups
Introduction
Aromatic polyimides are well recognized as a class of high performance materials due to their remarkable thermal and oxidative stabilities and excellent electrical and mechanical properties for long time periods of operation [1], [2]. Unfortunately, strong interaction between polyimide chains and their rigid structure make them intractable. Poor thermoplastic fluidity and solubility are the major problems for wide application of polyimides. Thus, to overcome these processing problems various approaches have been carried out by incorporating flexible units such as –NHCO–, –O–, and –SO2–, and some of which are commercialized [3], [4].
Among them, polyamide-imide (PAI) is the most successful material, which combines the advantages of high-temperature stability and processability. In our previous studies, we have applied the phosphorylation polycondensation technique to prepare novel and soluble PAIs from imide-containing dicarboxylic acids and aromatic diamines [5], [6], [7], [8], [9]. This route provides significant advantages in manufacturing operations compared with conventional methods.
Adamantane is a highly symmetrical tricyclic hydrocarbon which consists of fused chair-form cyclohexane rings [10]. The unique structure of this substance is reflected in highly thermal and oxidative stabilities, and low hydrophobicity. Adamantane has been incorporated into many high-temperature polymers such as poly(ether ether ketone)s [11], polyamides [12], [13], polyimides [13], polysulfones [11], and polycarbonates [14], subsequently producing increased thermal stability, solubility and glass transition temperature. However, there is limited literature reported on the synthesis and characterization of PAI containing adamantyl group.
In the present study, we report the synthesis and characterization of a series of new PAIs containing a pendent adamantyl group. A new adamantyl-containing diimide-dicarboxylic acid, 4-(1-adamantyl)-1,3-bis(4-trimellitimidophenoxy)benzene (ADBTB), was synthesized and polymerized with various synthesized diamines to obtain these PAIs. The crystallinity, solubility, thermal and tensile properties of these PAIs are also discussed.
Section snippets
Materials
Adamantyl resorcinol (ADRL) was prepared by alkylating resorcinol with 1-bromoadamantane in refluxing benzene, m.p. 247–248°C (Lit. [11] 249–250°C). 2,2-Bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (DA-1) [15], 3,3′,5,5-tetramethyl-2,2-bis[4-(4-aminophenoxy)phenyl]propane (DA-2) [16], 1,4-bis(4-aminophenoxy)-2-tert-butylbenzene (DA-3) [17], 1,4-bis(4-aminophenoxy)-2,5-di-tert-butylbenzene (DA-4) [18], 2,2′-dimethyl-4,4′-bis(4-aminophenoxy)biphenyl (DA-5) [19], and
Synthesis of diimide-dicarboxylic acid
The synthetic route to the new adamantyl-containing diimide-dicarboxylic acid monomer, ADBTB, is shown in Scheme 1. The bisphenol compound, adamantyl resorcinol (ADRL), was prepared by alkylating resorcinol with 1-bromoadamantane in refluxing benzene without adding any catalyst [11]. The compound ADRL was reacted with p-chloronitrobenzene in the presence of potassium carbonate and afforded the dinitro compound ADBNB. It was obtained in high yield (90%) and purified by recrystallizing in glacial
Conclusions
This study had successfully synthesized a new diimide-dicarboxylic acid, ADBTB, containing a rigid and bulky adamantyl pendent group. A series of novel PAIs were prepared by the direct polycondensation from the diimide-dicarboxylic acid with various diamines. These PAIs exhibited amorphous nature as well as mechanical properties. The results presented herein also demonstrate clearly that incorporating the adamantyl group into the polymer backbone remarkably enhanced the solubility and thermal
Acknowledgements
The authors thank the National Science Council of the Republic of China for support of this work under grant NSC 88-2216-E011-008.
References (22)
- et al.
Polymer
(1999) - et al.
Polymer
(1998) - et al.
Polyimide: fundamentals and applications
(1996) - et al.
Polyimides and other high-temperature polymers
(1991) - et al.
Polyimide
(1991) - et al.
Chem Mater
(1998) - et al.
J Polym Sci, Part A: Polym Chem
(1998) - et al.
J Polym Sci, Part A: Polym Chem
(1999) - et al.
Macromol Chem Phys
(1999) - et al.
Polym Int
(1999)