Hypercrosslinked polyarylates

Two polyarylates, I and II, composed of residues of isophthalic acids and two different bis-phenols, were taken for the preparation of networks [132]  

The macromolecule of polyarylate I has a voluminous side substituent in the bis-phenol unit and, therefore, it is more rigid than the chain of polyarylate II. In accordance with this, polyarylate I produces networks of higher porosity than polyarylate II crosslinked at the same concentration of the initial EDC solution (Table 9.2). Interestingly, a markedly higher dilution (0.055 g/mL) is required to obtain a porous polyarylate, as compared with that used for preparing hypercrosslinked polystyrene. 

C = concentration of polyarylate in EDC. Reprinted from [132] with permission of Elsevier. 

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Table 9.2 Properties of hypercrosslinked polyarylates crosslinked with nnonochlorodimethyl ether (1 mol per repeating unit). Synthesis conditions 80°Q lOh, 1,2-ethylene dichloride, SnCU (1 mol per mole of the ether)...

Usually crosslinking of linear polystyrene even in a more concentrated solution, 0.125 g/mL, in EDC results in the formation of highly porous materials with the apparent specific surface area of 1000 m/g, while further dilution changes the porosity only insignificantly.) Porous crosslinked polyarylates swell in n-heptane, a precipitating medium for the polymer precursor, and, therefore, they also belong to the family of hypercrosslinked polymers. 

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