| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1993: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1992: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
Stirene-methyl methacrylate copolymers were studied as copolymers composed of two sterically different monomers, A and B.Statistical, equimolar diblock and alternating copolymer samples of this system were molecularly characterized and thermally analyzed on differential scanning calorimeter. The thermograms weobtained were transformed into enthalpy : from enthalpy-temperature plots, glas s transiton temperature (Tg), independent of operational conditions, were determined. It was found that the Tg's thus determined depend not only on chemical composition (M) but also on on monomer arrangement, that is, primary structure of copolymer. With the run number (R) as a parameter expressing the primary stucture, it was found that Tg can be written as a sum of separated terms of M and R.This means that Tg of copolyumer can be described quantitatively by a dyad model : there are three dyads, AA, BB and AB in a copolymer chain.
This idea was applied to poly(methyl methacrylate), the tacticity dependence of which was studied. Since tactic polymers can be considered as copolymers composed of sterically different dyads, meso (m) and racemo (r), one can say that Tg of steric copolymer is specified with a set of three triads, mm, rr and mr. This deduction was comfirmed experimentally with the date of poly(methyl methacrylate). It should be noted that there is a difference chemically different copolymers and sterically different ones. The former are prepared on a statistics of reaction probability specified by monomer reactivity ratio, while the latter are prepared by changing the polymerization conditions. That means the variations in statistics of reaction probability. Once this difference was realized, the long-standing problem of the tacticity dependence of Tg of poly(methyl methacrylate) was clearly solved for the first time.
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