Polyformals, structures

High molecular weight samples of the polyformal were kindly supplied by General Electric. The structure of the repeat unit is shown in Figure 1 as well as the structure of a partially deuter-ated form which was synthesized (9) to reduce proton crossrelaxation. A 10 weight percent solution of the polymer in deu-terated tetrachloroethane was prepared in an NMR tube, subjected to five freeze, pump, thaw cycles and sealed. 

Structure of the polyformal repeat unit and the deuterated analogue. 

Earlier, we have synthesized polyformal oximates (PFO) on the basis of di-aeetophenyloxid dioxime and methylene eloride. The aromatic polyether has possessed a new eonjunetion of chemical fragments in a polymeric chain due to a structure of the initial monomers [2],... 

Reaction of a mixture of BPA, potassium hydroxide pellets, Aliquat 336 (0.1 mole per mole of BPA) in refluxing methylene chloride for 15 hr gave, after methanol precipitation, a high molecular weight polyformal (, In] = 0.59 dl/g in 70% isolated yield. Proton and NMR spectra confirmed the structure of j6. Interestingly, because of the apparent kinetics of this reaction, kb ka (equation 6), methylene chloride can actually be used as the solvent and reactant in this condensation polymerization reaction. 

NaOH solution was added intermittently to maintain the pH between 10 and 11.5. The entire reaction mixture was then added to 500 ml of methanol. The precipitated pol5nner was filtered and dried obtained 8.35 g. This material was redissolved in CH2CI2, filtered to remove some NaCl, and reprecipitated by adding to methanol. The polymer was filtered and dried giving 7.6g of the block copolyformal-carbonate [nT = 0.66 dl/g DSC showed only one Tg, 120°C a compression molded plaque was flexible and essentially clear. The C-NlfR spectrum was in complete accord with the assigned structure showing a polyformal/polycarbonate ratio of 48 52 (theory, 49 51). 

Figure 9. Structural representation of a polyester, polyether, and polyformal employed in a chemically amplified resist.

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