H-D ISOTOPE AND CHAIN-LENGTH DEPENDENCE OF PHASE-SEPARATION IN QUENCHED N-ALKANE BINARY COMBINATIONS IN THE CRYSTALLINE STATE

被引：25

作者：

DORSET, DL ^{[1
]}

SNYDER, RG ^{[1
]}

机构：

[1] UNIV CALIF BERKELEY,DEPT CHEM,BERKELEY,CA 94720

来源：

MACROMOLECULES | 1995年 / 28卷 / 24期

关键词：

D O I：

10.1021/ma00128a061

中图分类号：

O63 [高分子化学（高聚物）];

学科分类号：

070305 ; 080501 ; 081704 ;

摘要：

Certain binary n-alkane combinations, quenched to room temperature from the comelt, form metastable solid solution crystals that subsequently undergo spontaneous demixing. The degree and rate of phase separation are known to depend upon the chain-length difference of the two components. Recently, we have found that, in addition to the chain-length difference, the isotopic composition (H or D) can also be an important factor affecting the separation. We report here electron diffraction and calorimetric measurements, revealing the relative tendencies for microphase separation for the four possible isotopic combinations in C-30/C-36 (depending on whether each ingredient is perhydrogenated or perdeuterated). The isotope effect on phase stability is shown to be qualitatively similar to that of changing the chain-length difference, if the volume difference between CH2 and CD2 methylene groups, respectively, is expressed in terms of chain length. This trend is explored further for binaries C-30/C-n', where n' is systematically increased. Measurements made in this study are then compared to those from vibrational spectroscopy.

引用

页码：8412 / 8418

页数：7

共 24 条

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