摘要
Based on the perfect rotational isomeric state model of isotactic polypropylene, the separation distances between an initial left helix stem and its re-entry stems have been investigated. The intervals are defined by the formulae $$D_1 = \frac{{1.54}}{3}\sqrt {8(k_1^2 + k_2^2 + k_1 k_2 )/3} ( \times 10^{ - 1} nm)$$ for the left helix re-entry stem and $$D_2 = \frac{{1.54}}{3}\sqrt {8[k_1^2 + k_2^2 + (k_1 - 1)k_2 + 1/3]/3} ( \times 10^{ - 1} nm)$$ for the right helix re-entry stem, wherek 1 andk 2 are integers. The right helix one is less existing because of possessing high energy. The most plausible fold conformation is tg? tg? tg+ g+ g? for the most adjacent (010) fold. The next minimum energy fold segments are tg? g? tg+ tg+ tg?, g+g? tg?tg+g+ t and g+g?g?tg+ tg+ t.
Based on the perfect rotational isomeric state model of isotactic polypropylene, the separation distances between an initial left helix stem and its re entry stems have been investigated. The intervals are defined by the formulaeD 1=1.5438(k 2 1+k 2 2+k 1k 2)/3 (×10 -1 nm) for the left helix re entry stem and D 2=1.5438[k 2 1+k 2 2+(k 1-1)k 2+1/3]/3 (×10 -1 nm) for the right helix re entry stem, where k 1 and k 2 are integers. The right helix one is less existing because of possessing high energy. The most plausible fold conformation is tg -tg - tg +g +g - for the most adjacent (010) fold. The next minimum energy fold segments are tg -g -tg +tg +tg -, g +g -tg -tg +g +t and g +g -g - tg +tg +t.
基金
ProjectsupportedbytheNationalNaturalScienceFoundationofChina
