312 Research Article Received: 5 February 2010 Revised: 18 March 2010 Accepted: 19 March 2010 Published online in Wiley Online Library: 27 October 2010 (wileyonlinelibrary.com) DOI 10.1002/pi.2950 Phosphorus-containing poly(ester-imide) – polydimethylsiloxane copolymers Corneliu Hamciuc, ∗ Elena Hamciuc, Diana Serbezeanu, Tachita Vlad-Bubulac and Maria Cazacu Abstract New phosphorus-containing poly(ester-imide)-polydimethylsiloxane copolymers were prepared by solution polycondensation of 1,4-[2-(6-oxido-6H-dibenz<c,e><1, 2 >oxaphosphorin-6-yl)]naphthalene-bis(trimellitate) dianhydride with a mixture of an aromatic diamine (1,3-bis(4-aminophenoxy)benzene) and α,ω-bis(3-aminopropyl)oligodimethylsiloxane of controlled molecular weight, in various ratios. Poly(amic acid) intermediates were converted quantitatively to the corresponding polyimide structures using a solution imidization procedure. The polymers are easily soluble in polar organic solvents, such as N-methyl-2-pyrrolidone and N,N-dimethylformamide, as well as in less polar solvents such as tetrahydrofuran. They show good thermal stability, the decomposition temperature being above 370 ◦ C. The glass transition temperatures are in the range 165–216 ◦ C. Solutions of the polymers in N-methyl-2-pyrrolidone exhibit photoluminescence in the blue region. c  2010 Society of Chemical Industry Keywords: phosphorus-containing polymers; poly(ester-imide)-polydimethylsiloxane copolymers; thermal stability; photolumines- cence INTRODUCTION High-performance polymers are used in applications demanding service at enhanced temperatures while maintaining their struc- tural integrity and excellent combination of chemical, physical and mechanical properties. Wholly aromatic polyimides are generally the polymers of choice for these applications due to their many desirable characteristics including good thermo-oxidative stability and excellent mechanical properties. 1–3 However, aromatic poly- imides are often insoluble in their fully imidized form, presenting serious processing difficulties. The introduction of ether, amide, ester or other flexible groups into the main chain of aromatic poly- imides has been focused towards enhancing solubility of these polymers, with a minimum sacrifice of their thermal stability. 4,5 Polysiloxanes are polymers that have many important prop- erties: thermal resistance, low dielectric constant, low sur- face free energy and high gas permeability. 6,7 Incorporation of flexible polysiloxane segments into polyimide structures leads to polymers with interesting properties. Thus, poly- imide–polydimethylsiloxane copolymers exhibit good thermal and mechanical properties, good processability, low water ab- sorption, atomic oxygen resistance, low dielectric constant and excellent adhesion. They have become potential candidates for applications in microelectronics, printed circuits, gas-permeable membranes, adhesives and the aerospace industry. 8–16 The most widely applied flame-retardant materials containing halogen atoms have the disadvantage of toxicity due to hydrogen halide formed during combustion. Recently, much research effort has been devoted to halogen-free compounds, in particular polymers. 17–19 The requirements for a fire-resistant polymer include high thermal stability, low heat of combustion and low combustion heat release rate. Polymers that undergo carbonization upon heating are much desired due to the resulting carbonaceous char, which produces an insulating layer on the polymer surface, and thus prevents combustion. The same effect is obtained by the use of silicones that, on combustion, form insulating silica. Also, an attractive way to improve the flame retardancy of a polymer is the introduction of phosphorus atoms into its unit structure. Thus, utilization of monomers containing bulky groups including phosphorus, such as 9,10-dihydro-9-oxa- 10-phosphaphenanthrene-10-oxide (DOPO), results in polymers with increased fire retardance. During decomposition they generate less toxic gases and smoke than halogen-containing polymers. Also, the incorporation of DOPO groups into polymers improves solubility, thermo-oxidative stability and adhesion and decreases birefringence. 20–31 The introduction of DOPO groups and polydimethylsiloxane (PDMS) sequences into the macromolecular chains of poly(ester- imide)s is expected to provide polymers with good performance characteristics, good solubility, high thermal stability and good fire retardance. In this article we report the synthesis of a series of poly(ester-imide) – PDMS copolymers containing pendant DOPO groups. For comparison a poly(ester-imide) without PDMS sequences was prepared. The properties of these polymers, such as solubility, thermal stability and glass transition temperature, as well as their photoluminescence (PL) characteristics were investigated. ∗ Correspondence to: Corneliu Hamciuc, ‘Petru Poni’ Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41 A, Iasi 700487, Romania. E-mail: chamciuc@icmpp.ro ‘Petru Poni’ Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41 A, Iasi 700487, Romania Polym Int 2011; 60: 312–321 www.soci.org c  2010 Society of Chemical Industry