Strutural Studies of Polyethers [-(CH₂)_mO-]_n. VIII. Polyoxacyclobutane Hydrate (Modification I)

Abstract

the sequence distribution, ~8% in the polymer composition, and ~50 % in the monomer feed are shown for a VC1-BMA copolymer. Errors of ~18% in the sequence distribution, ~4% in the polymer composition, and ~1 % in the monomer feed are shown for a BD-MMA copolymer. Large errors are not expected in any of the variables, but erroneous reactivity ratios may also arise from a cumulation of smaller errors.The effect on predicted reactivity ratios of an ~2% error in all variables is also shown in Table V for both the VC1-BMA and BD-MMA copolymers. It is doubtful that errors of this degree would occur in all variables simultaneously, but the error range found indicates the experimental care that must be taken in using this approach. Accurate measurement of variables will, however, give favorable reactivity ratio comparisons as shown in Table II. ConclusionsReactivity ratios may be predicted in copolymer systems susceptible to sequence distribution measurements by accurately knowing the monomer feed, the copolymer composition, and the copolymer sequence distribution. Reactivity ratios can be obtained with a minimum amount of polymer synthesis and may be used to predict desired copolymer compositions. The singlecopolymer reactivity ratio technique could possibly be used to illustrate shifts in reactivity ratios attributed to penultimate effects or polymerization mixture polarity changes.The single-copolymer reactivity ratio method may prove to be valuable in specific systems where accurate sequence distribution data can be obtained and the use of conventional methods for finding reactivity ratios is not practical.

Phonon dispersion and heat capacity in polyoxacyclobutane modification I

“…1a, b). The calculated spectral data are found to be in good agreement with the experimental data reported by Makino et al [2] for the ribbon like structure of POCB I. To the best of our knowledge no such detailed studies leading to correlation between the microscopic behavior and macroscopic properties have been reported in literature.…”

“…The normal mode frequencies obtained from this force field (Table 1) are found to be in better agreement with the observed infrared bands as compared with the previous calculations [2,3].…”

“…Modification III is (T 2 G 2 ) 2 type, has two chemical units in the fiber period of 7.21Å and D 2 as point group symmetry. The POCB I was found to be a crystal of polymer hydrate [-(CH 2 ) 3 -O-] n ·nH 2 O with ribbon like structure [2]. Makino et al [3] have reported normal mode analysis of isolated POCB I chain and that for polymer hydrate [2].…”

“…The POCB I was found to be a crystal of polymer hydrate [-(CH 2 ) 3 -O-] n ·nH 2 O with ribbon like structure [2]. Makino et al [3] have reported normal mode analysis of isolated POCB I chain and that for polymer hydrate [2]. In their calculation, the CH 2 group was assumed as a point mass which is a serious approximation because it hides all the modes coupled with dynamics of CH 2 group and then there contribution to thermodynamic behavior.…”

Effect of molecular weight and temperature on the isothermal crystallization of poly(oxetane)

“…The first term of this series is polyoxacyclobutane, polyoxetane or poly(trimethylene oxide), PTO, which is a semicrystalline polymer. Structural studies on this polymer have been carried out by Tadokoro et al [2][3][4] and four crystal modifications, one of which is an hydrate, have been found. The molecule assumes, depending on crystallization conditions, a planar zig-zag conformation in the hydrate (Modification I) and in Modification IV, a T3GT3G conformation in Modification II and a (T2G2)2 conformation in Modification III.…”