Poly Carbonate s

A fluorine-containing poly(carbonate) was first synthesized by Knunyants and co-workers from Bisphenol AF and phosgene.2 However, detailed properties of this polymer other than the softening temperature of 170°C have not been reported. 

It has been reported that high-molecular-weight poly(carbonate)s can be synthesized using A,A -carbonyldiimidazole as a condensing agent under mild conditions.4-5 However, the reagent is very sensitive to moisture and must be handled with extreme care. 

The following quaternary ammonium salts are used as phase transfer catalyst tetra-K-butylammonium chloride (TBAC), tetra-n-butylammonium bromide (TBAB), benzyltriethylammonium chloride (BTEAC), and benzyltriethylammo-nium bromide (BTEAB). Chlorinated hydrocarbons, such as dichloromethane (DCM), chloroform (CF), tetrachloromethane (TCM), 1,2-dichloromethane (DCE), and nitrobenzene (NB) are used as solvents. The effects of phase-transfer catalyst and solvent on the yield and reduced viscosity are summarized in Table 9.1. 

When TBAB is used as a phase-transfer catalyst, sodium hydroxide as a base, and DCE as a solvent, both the molecular weight and yield of the poly(carbonate) are relatively high. Bisphenol AF-derived poly(carbonate) (2) having reduced viscosity of 0.35 dl/g is obtained in a 84% yield at ambient temperature under the 

Bisphenol AF/Bisphenol A (unit ratio) Yield (%) Bred (dl/g) 

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It has been determined from X-ray diffraction measurements that polycarbonate containing Bisphenol AF moiety are all amorphous.6 The (Tg) of poly(carbonate)s increases with an increase in hexafluoroisopropylidene unit from 149°C for Bisphenol A poly(carbonate) (3) to 169°C for Bisphenol AF poly(carbonate) (2) (Table 9.3).6 Thermooxidative stability is also improved by the introduction of fluorine atoms into the isopropylidene units. The 10% weight-loss temperature (DT10) increases from 429 to 460°C and the residual weight (RW) at 500°C goes from 37 to 57% by perfluorination of the isopropylidene units. 

The solubility is generally improved by the introduction of fluorine atoms into aromatic condensation polymers. Poly(carbonate)s containing hexafluoroisopropylidene units are much more soluble than Bisphenol A poly(carbonate) (3). All of the hexafluoroisopropylidene-unit-containing poly(carbonate)s become soluble in acetone, ethyl acetate, chloroform, and dimethyl sulfoxide (DMSO) in addition to the solvents of Bisphenol A poly(carbonate) (3). Colorless, transparent, and flexible films are prepared from hexafluoroisopropylidene-unit-containing poly(carbonate)s by casting or pressing. 

The high refractive index of Bisphenol A poly(carbonate) (3) is decreased by the incorporation of the Bisphenol AF moiety. The refractive index of Bisphenol A poly(carbonate) (3) is 1.585,9 whereas that of Bisphenol AF poly(carbonate)s (2) is 1.426. Poly(carbonate)s containing a small amount of Bisphenol AF moiety can be used as sheaths of optical fibers of Bisphenol A poly(carbonate) (3). 

Table 9.2. Preparation of Fluorine-Containing Poly(Carbonate)s ...

Compositions of the ABS type may be mixed with other polymers. Suitable blend partners can be selected from poly(carbonate)s (PC)s, poly(ester)s, poly(ester carbonate)s and poly(amide)s (PA)s. Some especially preferred types, of these compounds and an overview of how to produced these types have been described (16). 

As a general example of another systems that show interesting responses from relaxational point of view, condensation polymers like poly(carbonate)s and poly (thiocarbonate)s are a new group of polymers to be analyzed. Poly(thiocarbonate)s... 

PTC) is a family of polymers whose thermal properties, Tg, unperturbed dimensions and partial specific volumes has been reported [248-252], The dielectric properties of these polymers were recently studied [253-256], Relaxational studies on poly(thiocarbonate)s are scarce, but on the contrary there is much information about relaxation processes of the analogues poly(carbonate)s (PC). Therefore the study of PTC is an interesting approach to get confidence about the motions responsible of the relaxational behavior of these polymers. 

A. Welle, M. Kroger, M. Dbring, K. Niederer, E. Pindel, and I. S. Chronakis, Electrospun aliphatic poly(carbonate)s nanofibers as tailored tissue scaffold materials. Biomater., 28, 2211-2219 (2007). 

In poly(carbonate)s oligomeric and polymeric halogenated aromatic compounds, such as a co-poly(carbonate) of bisphenol A and tetra-bromobisphenol A are useful monomers (13). Halogen containing flame retardants are generally used in amounts of up to 50 phr. 

The ROP of cydic carbonates such as trimethylene carbonate (TMC) to synthesize poly(carbonate)s (Scheme 14.3) has also been shown to be mediated by... 

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