Hexafluoroisopropylidene bisphenol

Aromatic poly(aryl ether ketone)s containing 1,4-naphthalene moieties were prepared by the reaction of a bisphenol and 2 in the presence of potassium carbonate in DM Ac at 160°C as depicted in Scheme 3. A typical polymerization was carried out as follows To a 100-ml round-bottom flask was added 8.32 g (O.OlOmol) of2, 3.36g (O.OlOmol) of4,4 -(hexafluoroisopropylidene) diphenol, 51.2 g ofDMAc, and 3.1 g (0.022 mol) of potassium carbonate. The mixture was heated to 160°C with stirring under nitrogen for 18 h. The mixture was allowed to cool to room temperature. The polymer was precipitated by pouring the reaction mixture into a blender containing about 100 ml of water, filtered, washed three times with water and dried to yield 8.1 g (92% yield) as a white powder. 

Research on fluorine-containing condensation polymers is rather limited compared to that on fluorine-containing addition polymers. This fact is attributed to the difficulty in synthesis and the high cost of fluorine-containing condensation monomers. Recently, 2,2-bis(4-hydroxyhpenyl)-1,1,1,3,3,3-hexafluoropropane (Bisphenol AF) with a hexafluoroisopropylidene unit, HOC6H4C(CF3)2-C6H4OH, was produced commercially from hexafluoroacetone and phenol, and now Bisphenol AF and its derivatives are available as condensation monomers. 

Table 9.2 shows the results of a preparation of a series of copoly(carbonate)s having a wide range of hexafluoroisopropylidene unit content. Reduced viscosity of copoly(carbonate)s (5) decreases gradually with increasing feed ratio of Bisphenol AF (1) to Bisphenol A (4). This is attributed to the lower nucleophi-licity of Bisphenol AF induced by strongly electron-withdrawing trifluoromethyl groups as described above. 

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. 

A contact angle by water is 86° for Bisphenol A poly(formal) (6), is increased to 93° by the introduction of 28 mol% of hexafluoroisopropylidene unit, and then becomes almost constant irrespective of fluorine content.12 As... 

The bond dissociation energy of phenylene-oxy bonds is not very different from that of oxy-methylenebonds. Accordingly, the two-step decrease in weight of hexafluoroisopropylidene-unit-containing poly(formal)s, especially Bisphenol AF poly(formal) (7), is not brought about by a different reaction mechanism from... 

Hexafluoroisopropylidene-unit-containing aromatic poly(ether ketone)s were first synthesized from an alkaline metal salt of Bisphenol AF (1) and 4,4 -difluoro-benzophenone.14 Cassidy and co-workers prepared hexafluoroisopropylidene-unit-containing poly(ether ketone)s by condensing 2,2-bis[4-(4-fluorobenzoyl)-phenyl]-l,l,l,3,3,3-hexafluoropropane (9) and 2,2-bis[4-(4-fluorobenzoyl)-phenyljpropane (10) with Bisphenol AF (1) or Bisphenol A (4) (Scheme 7).15 The reactions are nucleophilic aromatic displacements and were conducted in DMAc at 155- 160°C with an excess of anhydrous potassium carbonate. After 3 to 6 h of reaction, high-molecular-weight poly(ketone)s are obtained in high yields. 

Sinicropi et al. (1996a) measured hole mobilities of ENA-B doped into a series of polymers poly(styrene) (P-1), bisphenol-A polycarbonate (P-2), pofy(4,4 -isopropylidene bisphenylene-co-4,4 -hexafluoroisopropylidene)bis-phenylene (50/50) terephthalate-co-azelate (65/35) (P-3), poly(4,4 -(2-norbotyli-dene)diphenylene terephthalate-co-azelate (40/60) (P-4), a phosgene-based polyester carbonate (P-5), and poly(vinyl butyral) (P-6). The ENA-B concentrations were 45%. Figure 64 shows the room temperature field dependencies. The mobilities vary by over four orders of magnitude. The field and temperature dependencies were described as log/i fiEl/2 and -(TJT)2. Table S summarizes the results. 

Halogenated bisphenol derivatives can be used for the formation of polycarbonates. For example, bisphenol AF can be used instead of bisphenol A, giving polyfoxycarbonyloxy-1,4-phenylene(hexafluoroisopropylidene)-1,4-phenylene]. The formulas for two other halogenated polycarbonates are shown below ... 

Nitrile-functional, (hexafluoroisopropylidene)diphenol-basedpoly(ar-ylene ether) copolymers with pendent sulfonic acid groups can be prepared by the copolymerization of 4,4 -(hexafluoroisopropyUdene)diphenol, 2,6-dichlorobenzonitrile, and 3,3 -disulfonate-4,4 -dichlorodiphenyl sulfone. Hexafluoroisopropylidene)diphenol is a fluorinated bisphenol A. 

The other important diol which finds wide application in synthesis of flame retardant epoxy thermosets is 4,4 -isopropylidene bis(2,6-dibromo-phenol) (tetrabromobisphenol-A,TBPA).The primary use of TBPA is as a reactive flame retardant in epoxy resin-based circuit boards and in electronic enclosures made of polycarbonate-acrylonitrile, butadiene-styrene, etc. Hexafluorobisphenol-A (bisphenol-AF, hexafluoroisopropylidene diphenol) has also been used for the synthesis of fluorinated epoxy resin aiming at the anticorrosion coatings market for industrial vessels and pipes. The key disadvantages of fluorinated epoxies are their relatively high costs and low Tg, which limit their commercialisation. Thus utilisation of such diols in vegetable oil-based epoxy resins may result in similar performance. 

Kim et al. [47] prepared three PAEs with pendant -CF3 groups from 2,2 -feiXtrifluoromethyl)-4,4 -dinitro-l,T-biphenyl and bisphenols (BEA, 4,4 -(hexafluoroisopropylidene) diphenol (6F-BPA), and 4,4-biphenol) through meto-activated nucleophilic nitro displacement reaction and investigated their properties. Scheme 2.6 shows the structures of monomers and polymers. 

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