Phosphorus-Containing Polysulfones

JCei/u ofds Polysulfones, polysulfonylation, electrophilic aromatic substitution, post-polymerization, chemical modification 

Aromatic polysulfones are a family of amorphous, thermoplastic polymers with phenylene, sulfone (-SO -), ether (-0-), and in some cases, other groups in the chain, that possess remarkable thermal and chemical stability, excellent strength and flexibility, transparency, as well as high glass transition temperature and good film forming properties. In addition they are mainly important as high-quality semipermeable membranes, as an alternative to cellulosic 

Vikas Mittal (ed.) High Performance Polymers and Engineering Plastics, (167-204) 

Despite these enumerate benefits, however, polysulfones have also some disadvantages in practical uses, such as their rather hydrophobic nature, the non-resistance to low polar organic solvents or to UV radiations. For this reason, there is a high interest in the chemical modification of polysulfones, which alter their chemical nature to some degree, but do not scarify their excellent physical, chemical and mechanical properties. 

The synthesis of polysulfones (PSF) can be performed by two main routes a polysulfonylation process, which is a classical electrophilic aromatic substitution [1], or a polyether synthesis, which is a nucleophilic substitution of activated aromatic dihalides [2,3]. 

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Petreus Oana, Avram Ecaterina, and Serbezeanu Diana. Synthesis and characterization of phosphorus-containing polysulfone. Polym. Eng. Sci. 50 no. 1 (2010b) 48-56. 

Petreus Oana, Lisa Gabriela, Avram Ecaterina, and Rosu Dan. Thermal degradation and pyrolysis study of phosphorus-containing polysulfones. J. Appl. Polym. Sci. 120 no. 6 (2011) 3233-3241. 

New phosphorus containing polysulfones could be obtained by using different phosphorus containing diols in the classical synthesis of PSF (Scheme 6.4). Diols can contain phosphorus in main chain position or incorporate in a phenanthrene-type ring as side chain. These different phosphorus-containing diols form aromatic polyethers by polycondensation with dihalogen-substituted aromatic sulfones [48]. The chain structure of the polymer (aromatic or aliphatic) and the position of phosphorus in the chain influence the polymer properties (electroluminescence [49,50], flame retardancy [51], liquid crystal properties [52]). 

Another approach in the synthesis of phosphorus containing polysulfones is the reaction between bisphenol S and a haloge-nated phosphorus containing derivative (Scheme 6.5). When spi-rocyclic pentaerythritol di-(phosphate monochloride) was used as monomer [53], triethyl amine was added to cap the resulted HCl. The obtained copolymer blended with an epoxy resin increased... 

Schema 6.5 Synthesis of phosphorus containing polysulfones from bisphenol S and halogenated phosphorus derivatives.

The FTIR spectra of phosphorus-containing polysulfones usually show the following absorption bands ... 

Table 6.2 Thermal stability of some phosphorus-containing polysulfones.

Differences Between Thermal and Thermo-Oxidative Degradation of Phosphorus Containing Polysulfones... 

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