SynopsisThe thermal decomposition of poly(butene-l sulfone), poly(pentene-1 sulfone), poly(hexene-l sulfone), poly(styrene sulfone), and polystyrene was investigated in helium a t a heating rate of 20°C/min using an experimental system which consists of a programmable pyrolyzer, a thermal conductivity detector, a mass chromatograph, and a vapor-phase infrared spectrophotometer. Poly(butene-1 sulfone), poly(pentene-1 sulfone), and poly(hexene-1 sulfone) displayed two-step decomposition; the primary products of decomposition at both steps were the comonomers (olefin and SOz). For poly(styrene sulfone), in addition to styrene and Son, products with molecular weights corresponding to dimers of styrene were obesrved. Decomposition of this polymer was compared with that of polystyrene, which formed mostly monomer.

Poly(methyl methacrylate), PMMA, is used as a model polymer to determine quantitatively the effect of molecular weight, molecular weight distribution, and tacticity on electron beam sensitivity. The heterotactic, syndiotactic, and isotactic stereoforms of PMMA were synthesized with molecular weights ranging from 10 4 to 10 7 and dispersivities from 1.2 to about 10. The G-values as determined by gamma radiation are about 1.3 and are independent of the three parameters. However, the solubility rate of PMMA is very dependent on the tacticity, and the relative solubility rates are in the order syndiotactic < heterotactic-s isotactic. The weightaverage molecular weight ratio was found to give a better correlation with solubility rate ratio than the number-average molecular weight ratio. The molecular size of the developer solvent was shown to have a much greater effect on the solubility rate than the molecular weight of the resist. An optimal developer solvent for PMMA can be systematically selected from a homologous series of nalkyl acetates which enhance the resist sensitivity.

SynopsisThe thermal decomposition of the Cq, C,, and CS polymethylene sulfones has been investigated at 275°C. under redured pressure. The gaseous deromposition products, collected and identified by infrared and mass-spectrometer analysis, were found to consist primarily of sulfur dioxide, olefins, alkanes, water, and hydrogen. A mechanism is proposed in which the rate-determining step consists of a roncerted attack of the sulfone group on the @-hydrogen atom with elimination resulting in a-olefins and a sulfinic arid. The sulfinir acid rapidly decomposes to give sulfur dioxide, hydrogen, and alkyl free radicals. The final products are formed by transfer and termination reactions of the free radicals and isomerization of the olefins in the presence of sulfur dioxide. Experimental evidence confirming this mechanism consists of rate studies of polymer decomposition whose initiation was found to be independent of polymer purity and of added free-radical initiators. A further proof of the rate-determining step was obtained by comparison of the decomposition products of bis-l,4-(butanesuIfonyl)butane with those of structurally comparable sulfinic acids: 1,4-butanedisulfinic acid and 1-butanesulfinic acid.

The contribution of parameters such as molecular weight, molecular weight distribution and stereochemistry to electron beam sensitivity of poly(methyl methacrylate), PMMA, has been investigated. The sensitivity is interpreted here as the minimum radiation dose required to obtain a predetermined solubility rate ratio, S/So = SR, of the exposed, S, and unexposed, So, material. The G‐value was foam be independent of molecular weight, molecular weight distribution, and stereochemistry. Data indicate that the weight average molecular weight ratio correlates better with SR than the number average molecular weight ratio. The tacticity of the resist and the developer solvent molecular weight or size have a large effect on solubility rate. Although the solubility rate pf isotactic PMMA is much greater than the syndiotactic and heterotactic stereoforms, the sensitivity appears to be independent of tacticity. In a homologous series of n‐alkyl acetate developer solvents, the molecular size of the solvent has a greater effect on the solubility rate than the molecular weight of the resist. A developer solvent has been selected from the n‐alkyl acetates which enhanced the sensitivity of PMMA.

Monomers and polymers of 3‐vinyl‐N‐ethylcarbazole, 3‐vinyl‐N‐methylphenothiazine, 3,7‐divinyl‐N‐methylphenothiazine, N‐acrylylcarbazole, N‐acrylylphenothiazine, and N‐acrylyl‐ and N‐methacrylyldibenzazepine have been synthesized. The synthetic procedures for preparing the monomers and polymers are described.