Polyphosphazenes optical materials

Optical Materials. The polyphosphazene skeleton is electron-rich, which means that it provides a refractive index increment compared to conventional saturated organic backbones. In addition, the macromolecular substitution synthesis aUows highly unsaturated organic side groups to be linked to the skeleton in ways that allow the refractive index, the color, the liquid crystalline, and nonlinear optical characteristics of the polymer to be finely tuned. Thus, the use of these polymers in opto-electronic (photonic) switches and lens systems is a subject of growing interest. 

Polyphosphazenes are suitable materials to be used as carriers for nonlinear optical (NLO) chromophores. Second order NLO properties have been studied for the polymer (128) and blends of (129) with the free chromophore (130) or the cyclophosphazene (131). All systems have glass transition temperatures higher than 135°C and a wide transparency window. The system (129)-(130) appears to exhibit the highest second-harmonic generation (SHG) response. For possible applications the SHG capability has to be enhanced. ... 

The polyphosphazene backbone is also transparent to radiation from the near infrared to 220 nm. That explains their stability to radiation in the visible and near-UV region and the interest in polyphosphazenes as optical and photonic materials. ... 

Several of the papers in this volume focus not only on the synthesis of new materials but also on properties and applications. The applications of polysiloxanes as photoresists (van de Grampel, Chapter 8), polyphosphazenes for microencapsulation of biologically active species (Allcock, Chapter 17), and inorganic-organic hybrid oxopolymers with optical applications (Schrnidt, Chapter 15) are examples. New information is also presented on the photochemistry and photophysics (Hoyle, Chapter 25), the oxygen permeability (Kajiwara, Chapter 21), and a variety of optical properties of polyphosphazenes (Allcock). 

Polyphosphazenes are some of the most diverse inorganic type polymers known. The presence of phosphorus and nitrogen atoms in the backbone and the unusual method of synthesis, with which an almost infinite variety of side groups and combinations of (fifferent side groups can be linked to the backbone, confer to the polymers a variety of interesting properties (1-3). Therefore, the applications of polyphophazenes can be very broad, and includes flame retardent materials, high performance elastomers, optical and electronic materials, biomedical materials etc.(3-8). The application potentials of some elastomers included aerospace, marine, oil exploration and industrial fields. However, despite to the hundreds of the polyphosphazenes synthesized, they are still expensive to produce and very few of them have been commercialized (6). 

Since both miscible and immiscible phosphazene blends are of considerable interest as membrances, biomaterials, or flame retardant materials, it is worthwhile to study the compatibility of these kinds of blends in more detail in order to understand more about the interaction between the polymer pair and the stability of the blends. Our goal in this study is to prepare PCPP/PS blends and investigate the compatibility and tile properties of the blends by optical clarity, DSC, SEM, FTIR, TGA and LOI. PCPP/PS is chosen in this study because (a) PCPP is known to be flame retardant (5), (b) polystyrene is a well-known versatile organic polymer and has been selected to gi t or blend with phosphazene polymers in most of the polyphosphazene-organic polymer hybrids systems (14,15), and (c) the similarity of aromatic side groups in both of the polymers. In addition, since rcPP has a special thermotropic transition temperature, T(l), and in order to further understand tiie stability of the blends, the compatibility influenced by temperature is also studied before and after T(l) transition by DSC. 

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