SYNOPSISNew thioether-and thianthrene-containing poly(benzoxazo1e)s (PBOs) were synthesized from 4,4'-thiobis[3-chlorobenzoic acid] and thianthrene-2,7-and -2,8-dicarbonyl chlorides with commercially available bis-o-aminophenols. Polymers were prepared via solution polycondensation in poly(phosphoric acid) at 90-200°C. Transparent PBO films were cast directly from polymerization mixtures or rn-cresol. The films were flexible and tough. Nonfluorinated PBOs were soluble only in strong acids and A1Cl3/NO2R systems by forming complexes with the benzoxazole heterocycle. Glass transition temperatures ranged from 298-45OoC, and thermogravimetric analysis showed good thermal stabilities in both air and nitrogen atmospheres. 0 1995 John Wiley & Sons, Inc.

8-dicarboxylic acids plus a synthetic intermediate, 4,4'-thiobis[3chlorobenzoic acid], have been synthesized in good yields via nucleophilic aromatic substitution of Na2S on !V,lV-dimethyl-3,4-dichlorobenzamide. New aromatic polyamides having inherent viscosities of 1.29-2.39 dL/g were prepared by the direct polycondensation reaction of the dicarboxylic acids with 4,4'-oxydianiline and 1,4-phenylenediamine in iV-methyl-2-pyrrolidinone (NMP) using triphenyl phosphite (TPP) and pyridine. The fused-ring thianthrene-based polyamides were more soluble than analogous poly(thioether amide)s. Polymer films were cast from either ALY-dimethylformamide (DMF) or NJJdimethylacetamide (DMAcVLiCl solutions and analyzed by FTIR and NMR. All prepared aramids displayed good thermal stability by DSC and TGA.

Thianthrene‐2,3,7,8‐tetracarboxylic dianhydride was synthesized via nucleophilic aromatic substitution of N‐phenyle‐4,5‐dichlorophthalimide with thiobenzamide, thioacetamide, and sodium sulfide. This monomer was then polymerized with aromatic diamines by the con‐ventional low temperature technique in N,N‐dimethylacetamide (DMAc) to yield soluble poly(amic acid)s. Polyimides were obtained by thermal cyclization of the poly(amic acid) films. Polymers obtained formed creasable thin films and had excellent thermal stability in air and nitrogen. The bent thianthrene structure limited crystallization and chain packing, as indicated by x‐ray analysis. The amorphous thianthrene‐containing polyimides were only soluble in H2SO4. © 1995 John Wiley & Sons, Inc.

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The time translation operator for neutrino mass states is often taken to be e −iEt/h . This is not relativistically invariant. In kaon mixing, physicists use e −imc 2 τ /h where τ is the proper time of the kaon state. The factor mc 2 τ is the rest frame value of the four vector product p µ x µ which is an invariant quantity. If −ip µ x µ is used in neutrino oscillation formulae instead of −iEt, the scale of the ∆m 2 ij is reduced by a factor of two.