Polyetherification

Polyetherification - A poLyether qrnthesis according to equation. A) was first described by Union Carbide Corporation (6). In this process ether bonds 

ACS Symposium Series American Chemical Society Washington, DC, 1974. 

PEODDCT POLTOER REPEAT DNIT(S) SOmwING BEHAVIOUR 

Polyethersulphone 720P (ICI) -[-0-0- 2 ] -[-O -0- 2-]- 33b 4 90 5p injection moulds iirith sane difficulty in conventional equipment 

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Polyetherification is similar to a polycondensation process formation of high molecular weight polymer requires precise adjustment of composition to approximately 1 1 ratio of bisphenol to dihalosulfone. Trace amounts of water gready reduce the molecular weight attainable owing to side reactions that unbalance the stoichiometry (76). The reactivity of the halosulfone is in the order expected for two-step nucleophilic aromatic displacement reactions ... 

In the polyetherification route the condensation reaction proceeds by reactions of types (1) and (2) where M is an alkali metal and X a halide. 

The Ar and/or Ar group(s) will contain sulphone groups and if Ar = Ar then identical products may be obtained by the two routes. Polyetherification processes form the basis of current commercial polysulphone production methods. These will be discussed further below. 

Alternative approaches were developed by Rose and his colleagues at involving polyetherification reactions, in principle very similar to the polyetherification processes that they had developed earlier for the manufacture of polysulphones (Table 21.3), either by self-condensation of products such as IV or reaction between intermediates V and VI (Figure 21.8). 

The thermotropic aromatic main chain liquid crystalline polymers are also prepared by the phase transfer catalyzed aromatic nucleophilic polymerization [87]. Polyetherification of bis(4-chloro-3-nitrophenyl) sulfone with mesogenic aromatic diols is shown below ... 

Condensation of an activated aromatic halide witli eitlier an alkali metal tliio-phenoxide or an alkali metal sulfide is performed under the same experimental condensations as used for polyetherification (Scheme 6.33).248... 

Polytetramethyleneglycol (polytetrahydrofuran) is formed by ring opening polyetherification of tetrahydrofuran. Branched polyalkyleneoxides are formed using polyfunctional alcohols such as trimethylolpropane and pentaerythrite. The products are liquids or waxes depending on the molar mass. Polyalkyleneoxides are often precursors for demulsifiers. 

Some particularities of the extraction of ions from an aqueous organic phase, and of the phase catalyzed polyetherification will be summarized. These will represent the fundamentals of our work on the synthesis of some novel classes of functional polymers and sequential copolymers. Examples will be provided for the synthesis of functional polymers containing only cyclic imino ethers or both cyclic imino ethers as well as their own cationic initiator attached to the same polymer backbone ABA triblock copolymers and (AB)n alternating block copolymers and a novel class of main chain thermotropic liquid crystalline polymers containing functional chain ends, i.e., polyethers. 

Several particularities of phase transfer catalyzed polyetherification are as follows. Stoichiometric phase transfer catalyzed pol)rmerizations do not take place between stoichiometric ratio of monomers, since the nucleophilic monomer is always transferred in a small amount into the organic phase. Consequently, because their reaction is a non-stoichiometric one there is no need for an equimolar ratio between the two monomers to get polymers with high molecular weights. High molecular weight polymers are usually obtained also at low conversions. In several cases, even at 100 percent conversion the polydispersity of the obtained polymers is low, i.e., "Hw/Hh 1.3. At any conversion, the organic phase contains only pol3rmers with electrophilic chain ends, even when the nucleophilic monomer was used in excess. 

All these particularities of phase transfer catalyzed polyetherification were staying behind our approach to the design of new macromolecules. 

Under carefully selected reaction conditions, the polyetherification of an u)-phenol oligomer with an a, o)-di(electrophilic) oligomer produces unexpectedly pure ABA triblock copolymers(11). while the polyetherification of an a, u)-di(electrophilic) oligomer with an a, u)-di (nucleophilic) oligomer represents a new method for the synthesis of perfectly alternating (AB) block copolvmers(9-12.22). 

Recently we have developed a new class of thermotropic liquid crystalline (LC) main-chain pol3rmers, i.e., polyethers of mesogenic bis-phenols(16-17.23-26). Since the obtained polymers are not soluble in dipolar aprotic solvents, the only available synthetic avenue for their preparation consists in the phase transfer catalyzed polyetherification. 

What will phase transfer catalysis provide polymer chemistry within the near future It is apparently still to early to predict this. We are not yet in the possession of many elemental mechanistic and kinetic understandings in order to answer questions like, for example, why not "living polyetherification "... 

Copolymers. Copolymers from mixtures of different bisphenols or from mixtures of dichlorosulfone and dichlorobenzophenone have been reported in the patent literature. Bifunctional hydroxyl-terminated polyethersulfone oligomers are prepared readily by the polyetherification reaction simply by providing a suitable excess of the bisphenol. Block copolymers are obtained by reaction of the oligomers with other polymers having end groups capable of reacting with the phenol. Multiblock copolymers of BPA-polysulfone with polysiloxane have been made in this way by reaction with dimethyl amino-terminated polydimethylsiloxane the products are effective impact modifiers for the polyethersulfone (79). Block copolymers with nylon-6 are obtained when chlorine-terminated oligomers, which are prepared by polyetherification with excess dihalosulfone, are used as initiators for polymerization of caprolactam (80). 

The polyetherification route to polyethersulfones can be adapted to the synthesis of polyethers containing strongly electron-withdrawing groups other than sulfone groups. Poly(l,4-oxyphenylenecarbonyl-l,4-phenylene) [27380-27 4] (6) is produced by condensation of 4,4 -dihydroxybenzophenone or by the self-condensation of 4-chloro-4 -hydroxybenzophenone. It has a melting point of 367°C and a glass-transition temperature of 154°C (83). 

Percec and Rodenhouse presented the first main-chain liquid crystalline polymer with a crown ether moiety in the backbone of the polymer [83], Liquid crystalline polyethers 63 were obtained by phase transfer catalyzed polyetherification of... 

It is evident that the way in which the network structure is developed will depend primarily on the type of polymerization reaction that is involved stepwise or chainwise. In the former case the network growth occurs smoothly, as schematically represented in Fig. 3.1, for the paradigmatic case of an A3 homopolymerization - e.g., a molecule with three OH groups that undergoes a polyetherification reaction. 

Equation (5.1) becomes a rigorous equation only in the case of stepwise polymerizations with equal initial reactivities, absence of substitution effects, and following a single reaction path. It may be also used when the reactivity ratio does not vary with temperature. This is, fortunately, the case of epoxy-amine reactions where the reactivity ratio of the secondary to the primary amine is approximately constant in a broad temperature range. But, even in this case, the parallel polyetherification of epoxy groups must be negligible to keep a single reaction path. 

On the other hand, Matsuda et al. [47] recently conducted systematic studies on catalysts for etherification reaction of wood with phenylglycidyl ether (PGE) [47]. It was found that, among various basic catalysts, the K salts of fatty acids accelerate the reaction remarkably, and a high WG indicating a high degree of polyetherification could be obtained. As shown in Table 1,... 

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