Polyphosphazene blends

Polyphosphazene films, prepared by solvent casting of either polyphosphazene polymers or polyphosphazene blends, have been actively studied for periodontal or bone tissue engineering. Duan et al. prepared poly[(ethyl... 

Figure 2.10 The relative pH of the degradation products is shown by the amount of sodium hydroxide required to neutralise the acid released during the degradation of the PLGA-polyphosphazene blends and its parent polymers PLGA and the poly(organo) phosphazene-PPHOS-EG50. Reproduced with permission from A.M.A. Ambrosio, H.R. Allcock, D.S. Katti and C.T. Laurencin, Biomaterials, 2002, 23, 7, 1667. 2002, Elsevier [62]...

Fig. 11 SEM micrographs of phase-separated sulfonated polyphosphazene blends a SPB3MPP-PVDF, b SPB3MPP-PAN, and c SPBPP-PBI...

Potta, T., Chun, C., Song, S.C. Injectable, dual cross-linkable polyphosphazene blend hydrogels. Biomaterials 31(32), 8107-8120 (2010). doi 10.1016/j.biomaterials.2010.07.029... 

Aryloxyphosphazene copolymers can also confer fireproof properties to flammable materials when blended. Dieck [591] have used the copolymers III, and IV containing small amounts of reactive unsaturated groups to prepare blends with compatible organic polymers crosslinkable by the same mechanism which crosslinks the polyphosphazene, e.g. ethylene-propylene and butadiene-acrylonitrile copolymers, poly(vinyl chloride), unsaturated urethane rubber. These blends were used to prepare foams exhibiting excellent fire retardance and producing low smoke levels or no smoke when heated in an open flame. Oxygen index values of 27-56 were obtained. 

Carter, R., Wycisk, R., Yoo, H. and Pintauro, P. N. 2002. Blended polyphosphazene/polyacrylonitrile membranes for direct methanol fuel cells. Electrochemical and Solid-State Letters 5 A195-A197. 

In another report polyphosphazene copolymers were synthesized from bis (2-methylphenoxy) phosphazene, which was sulfonated after polymerization. Polymers such as polyvinylidene fluoride, polyhexa-fluoropropylene, and polyacrylonitrile were used to produce a blended membrane system. Polymer blends, cross-linking, and other means of re-enforcement are... 

One method of reducing crystallinity in PEO-based systems is to synthesize polymers in which the lengths of the oxyethylene sequences are relatively short, such as through copolymerization. The most notable hnear copolymer of this type is oxymethylene-linked poly(oxyethylene), commonly called amorphous PEO, or aPEO for short. Other notable polymer electrolytes are based upon polysiloxanes and polyphosphazenes. Polymer blends have also been used for these applications, such as PEO and poly (methyl methacrylate), PMMA. The general performance characteristics of the polymer electrolytes are to have ionic conductivities in the range of cm) or (S/cm). 

Polyphosphazenes block copolymers containing sulfonimide side groups, (V), were prepared by Allcock et al. (4) and used in membrane blends in fuel cells. 

A number of liquid crystalline polyphosphazenes with mesogenic side groups have been prepared (48—50). Polymers with nonlinear optical activity have also been reported (51). Polyphosphazene membranes have been examined for gas, liquid, and metal ion separation, and for filtration (52—54). There is interest in phosphazene—organic copolymers, blends, and interpenetrating polymer networks (IPNs) (55—61) to take advantage of some of the special characteristics of phosphazenes such as flame retardance and low temperature flexibility. A large number of organic polymers with cydophosphazene substituents have been made (62). 

Examples of known phosphazene polymer blends are those in which phosphazenes with methylamino, trifluoroethoxy, phenoxy, or oligo-ethyleneoxy side groups form blends with poly(vinyl chloride), polystyrene, poly(methyl methacrylate), or polyethylene oxide).97 100 IPNs have been produced from [NP(OCH2CH2OCH2CH2OCH3)2] (MEEP) and poly(methyl methacrylate).101-103 In addition, a special type of IPN has been reported in which a water-soluble polyphosphazene such as MEEP forms an IPN with a silicate or titanate network generated by hydrolysis of tetraethoxysilane or tetraalkoxytitanane.104 These materials are polyphosphazene/ceramic composites, which have been described as suitable materials for the preparation of antistatic layers in the manufacture of photographic film. 

Hydrogels and amphiphilic membranes Poly(carbophosphazenes) and poly(thiophosphazenes) New condensation syntheses NLO and high refractive index polymers Microencapsulation of mammalian cells (PCPP) Polyphosphazene polymer blends and IPN s Borazine derivatives Poly(phosphazophosphazenes)... 

Among the various materials are crosslinked PAN, polyphosphazenes, polyphe-nylenesulfide, polyetheretherketone, and various polymer blends [28-31]. Particularly interesting is the use of zeolites as filler in organic polymers, which aims at improving the performance of (silicone-based) membranes for separations in nonpolar solvents, by adding more cross-links to the membrane material [32, 33]. 

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 specialty resins are expensive, produced in relatively small volumes either for a specific application or looking for a market niche. Their Tg > 200°C and modulus > 3 GPa. In 1991 the total world consumption of polysulfones (PSE) and polyethersulfones (PES) was 8.5 kton. Blends of the following polymers are known polyfluorocarbons, polysiloxanes, sulfur-containing polymers (PPS, PPSS, PES, and PSF), polyetherk-etones (PEK, PEEK, PEKK), polyimides (PI, PEI, and PAI), PAr, COPO, polyphosphazene (PHZ) and LCP. 

Inspired by the hierarchical structures that enable bone function, Deng et al. recently developed a mechanically competent 3D scaffold mimicking the bone marrow cavity and the lamellar structure of bone by orienting electrospun polyphosphazene-polyester blend nanofibers in a concentric manner with an open central cavity (Figure 11.9b and c) [66]. The 3D biomimetic scaffold exhibited mechanical characteristic similar to native bone. Compressive modulus of the scaffold was found to be within the range of human trabecular bone. When tuned to have desired properties, the concentric open macrostructures of nanofibers that structurally and mechanically mimic the native bone can be a potential scaffold design for accelerated bone healing. 

N.R. Krogman, et al., MiscibiUty of bioerodible polyphosphazene/ poly0aclide-co-glycolide) blends. Biomacromolecules 8 (4) (2007) 1306-1312. 

M. Deng, et al.. Dipeptide-based polyphosphazene and polyester blends for bone tissue engineering. Biomaterials 31 (18) (2010) 4898 908. 

A.L. Weikel, et al.. Miscibility of choline-substituted polyphosphazenes with PLGA and osteoblast activity on resulting blends. Biomaterials 31 (33)(2010) 8507-8515. 

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