Thermal, Mechanical, and Dielectric Properties of Novel Fluorinated Copoly(imide siloxane)s Anindita Ghosh, Susanta Banerjee Materials Science Centre, Indian Institute of Technology, Kharagpur 721302, India Received 18 December 2007; accepted 27 February 2008 DOI 10.1002/app.28298 Published online 6 May 2008 in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: Eight new poly(imidesiloxane)s copoly- mers have been prepared by one-pot solution imidization method. The polymers are made by the reaction of bisphenol-A dianhydride (BPADA) with four different fluorinated diamines and amino-propyl terminated poly- dimethylsiloxane (APPS). The polymers are named as 1a, 1b, 1c, and 1d, respectively, with a siloxane loading of 40 wt %. The second series of polymers where siloxane loading is 20 wt % were named as 1e, 1f, 1g, and 1h. The resulting polymers have been well-characterized by GPC, IR, and NMR techniques. The proton NMR indicates the siloxane loading is about 36–38% for the first series of polymers 1a–1d and a loading of 17–18% for the series of polymers 1e–1h. The films of these polymers showed low water absorption of 0.02% for the first series of polymers and 0.11% for the second series of polymers. Thermal, mechanical, and dielectric properties of these polymers have been evaluated and compared with their nonsi- loxane analogues. Preliminary investigations of melt processability of these polymers were also inves- tigated. Ó 2008 Wiley Periodicals, Inc. J Appl Polym Sci 109: 2329–2340, 2008 Key words: fluorinated polyimides; poly(imide siloxane); thermal properties; mechanical properties; dielectric con- stant; rheological properties INTRODUCTION High-performance polymers such as polyimides can be attributed to their outstanding properties such as excellent thermal and thermo-oxidative stability, sol- vent resistance, mechanical and electrical proper- ties. 1–6 They are widely used in electronic and micro- electronic industries, 7–10 aerospace fields 11,12 as well as membranes for gas separation. 13 To utilize the thermal stability of polyimides for further applica- tions, and also to take advantage of other properties of these classes of polymers, such as high chain ri- gidity, packing density, and polar chain interactions, it is desirable to synthesize soluble and/or melt- processable variations. Fluorinated polyimides have attracted much attention in the electronics industry because of their properties such as low dielectric constant, low moisture absorption, low permittivity, and high thermal and chemical resistance due to the high electronegativity of fluorine atoms and low electron polarizability of CF bonds. 14–17 Incorpora- tion of fluorine also enhances the solubility. 18 Solubilizations have been tried by several means such as introduction of flexible linkages, 19,20 bulky substituents, 21,22 or bulky units in the polymer back- bone, 23–25 noncoplanar, 26,27 or alicyclic 28 monomers. Additionally, an incorporation of siloxane unit to polyimides and related polymers 29–32 makes it possi- ble to increase the solubility and processability and, furthermore, to impart impact resistance, biocompat- ibility, low moisture uptake, low dielectric constant, thermooxidative resistance, low surface energy, and good adhesion properties to the substrate. Kuckertz et al. 33 first reported poly(imide siloxane), which was prepared from PMDA with various low molecu- lar weight amine-terminated siloxane dimers. Summers 34 incorporated APPS with various ratios (5, 10, 20, and 40%) of different molecular weight (M n  900–10,000 g/mol) into the 3,3 0 ,4,4 0 -benzophe- none tetracarboxylic dianhydride(BTDA) and 3,3 0 diaminodiphenylsulfone (3,3 0 -DDS)-based polyimide. Studies have also been done regarding incorporation of polydimethyl siloxane segment in the polymer backbone. Arnold et al. 35 have tried to incorporate varying amount of respective amount of siloxane in the polyimide backbone but incorporation has found to be less than that tried while investigation by Pechar et al. 36 have reported 22 and 41 wt % silox- ane incorporation where they attempted 20 and 40 wt % incorporation, respectively. Sun et al. 37 reported a novel poly(imidesiloxane) of trade name (SIM-2000) used as spun-on dielectric which pro- vided good high temperature stability at 4508C. Kri- potou et al. 38 investigated molecular mobility in rela- tion to morphology in polyimide-poly(dimethylsilox- Correspondence to: S. Banerjee (susanta@matsc.iitkgp. ernet.in). Journal of Applied Polymer Science, Vol. 109, 2329–2340 (2008) V V C 2008 Wiley Periodicals, Inc.