Molecular structure and rubber-like elasticity I.: The crystal structures of β gutta-percha, rubber and polychloroprene
Molecular structure and rubber-like elasticity I.: The crystal structures of β gutta-percha, rubber and polychloroprene
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DOI：
10.1098/rspa.1942.0024
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发表时间：
1942-03-01
影响因子：
--
通讯作者：
Bunn, CW
中科院分区：
文献类型：
--
作者：
Bunn, CW
本文用X射线衍射法测定了β-杜仲胶、橡胶和氯丁橡胶的晶体结构，β-杜仲胶（-CH_2-C（CH_3）= CH-CH_2-）_n为正交晶系，轴长a_0 = 7.78，b_0 = 11.78，c_0 = 4.72。四个长链分子平行于轴穿过这个细胞。空间群为P212121，一个结构单元的五个碳原子的坐标为：（CH_2）0.926（C）0.000（CH）0.000（CH_2）0.074（CH_3）0.970 0.110 0.146 0.074 0.110 0.277 0.676 0.960 0.177 0.462 0.980不对称;通过任何一个晶体的所有分子都是相同的--或者是左手的或者是右手的，而不是混合的。碳链是一个非平面的锯齿形，每个链单元C-C=C-C是平面的，具有反式构型，但连接键（CH 2-CH 2）位于不同的平面，平面-C-C-C =与平面-C-C=C-成115°角。a杜仲胶分子可能也具有反式双键构型，与β分子的不同之处仅在于CH 2-CH 2键的位置;因此，其链型与β分子不同。结晶橡胶（也称为（-CH 2- C（CH 3）= CH-CH 2-）n）是单斜晶系，并且具有a0 = 12.46 A，b 0 = 8.89 A，c 0 = 8.10 A，β= 92°。四个长链分子平行于轴穿过这个细胞。空间群为P21/a，一个结构链单元的10个碳原子的坐标为（CH 2）0.753（C）0.854（CH）0.845（CH 2）0.745（CH 3）0.968 0.899 0.865 0.905 0.959 0.876 0.802 0.703 0.542 0.457 0.773（CH 2）0.744（C）0.644（CH）0.659（CH 2）0.757（CH 3）0.532 0.834 0.874 0.905 0.834 0.828 0.326 0.215 0.052 0.975 0.268分子是不对称的;通过晶胞的分子中有两个是左手的，两个是右手的。任何一个分子的链碳原子形成非平面锯齿形，其中双键单元C-C = C-C具有cis-configuration。组成结构单元的两个异戊二烯单元C-C-C = C-C-在构型上不相同;变形似乎是由于分子间力。结晶聚氯丁二烯（-CH_2-CCl= CH-CH_2-）的结构与杜仲胶的结构完全相似。晶胞参数为a0 = 8.84 A，b 0 = 10.24 A，c 0 = 4.79 A，属正交晶系。碳和氯原子的坐标为（CH 2）0.077（C）0.033（CH）0.008（CH 2）0.970 Cl 0.167 0.054 0.115 0.034 0.099 0.243 0.278 0.000 0.787 0.509 0.000
The crystal structures ofβgutta-percha, rubber and polychloroprene have been determined by interpretation of X-ray diffraction photographs.βGutta-percha (—CH2—C(CH3)=CH—CH2—)n is orthorhombic, with axial lengths a0= 7.78 A,b0= 11.78 A,c0= 4.72 A. Four long-chain molecules pass through this cell parallel to thecaxis. The space group isP212121, and the co-ordinates of the five carbon atoms of one structural unit are: (CH2) 0.926 (C) 0.000 (CH) 0.000 (CH2) 0.074 (CH3) 0.970 0.110 0.146 0.074 0.110 0.277 0.676 0.960 0.177 0.462 0.980 The molecules are asymmetric; all the molecules passing through any one crystal are identical—either left-handed or right-handed, not mixed. The carbon chain is a non-planar zigzag; each chain unit C—C=C—C is planar, and has thetransconfiguration, but the connecting links (CH2—CH2) lie in a different plane; the plane —C—C—C = makes an angle of 115° with plane —C—C=C—. a Gutta-percha molecules probably also have thetransdouble-bond configuration, and differ fromβmolecules only in the positions of the CH2—CH2bonds; the chain form is thus different from that ofβmolecules. Crystalline rubber (also (—CH2— C(CH3)=CH — CH2— )n) is monoclinic, and hasa0= 12.46 A,b0= 8.89 A,c0= 8.10 A,β= 92°. Four long-chain molecules pass through this cell parallel to thecaxis. The space group isP21/aand the co-ordinates of the ten carbon atoms of one structural chain unit are (CH2) 0.753 (C) 0.854 (CH) 0.845 (CH2) 0.745 (CH3) 0.968 0.899 0.865 0.905 0.959 0.876 0.802 0.703 0.542 0.457 0.773 (CH2) 0.744 (C) 0.644 (CH) 0.659 (CH2) 0.757 (CH3) 0.532 0.834 0.874 0.905 0.834 0.828 0.326 0.215 0.052 0.975 0.268 The molecules are asymmetric; two of the molecules passing through the unit cell are left-handed and two right-handed. The chain carbon atoms of any one molecule form a non-planar zigzag, in which the double-bond units C— C=C— C have thecisconfiguration. The two isoprene units C —C—C=C —C— which make up the structural unit are not identical in configuration; the distortion appears to be due to intermolecular forces. The structure of crystalline polychloroprene (—CH2—CCl=CH—CH2— )nis completely analogous to that of (i gutta-percha. The cell is orthorhombic, witha0= 8.84 A,b0= 10.24 A,c0= 4.79 A. The co-ordinates of carbon and chlorine atoms are (CH2) 0.077 (C) 0.033 (CH) 0.008 (CH2) 0.970 Cl 0.167 0.054 0.115 0.034 0.099 0.243 0.278 0.000 0.787 0.509 0.000