Polymorphism and crystal structure identification in poly(aryl ether ketone ketone)s
Polymorphism and crystal structure identification in poly(aryl ether ketone ketone)s
复制标题
聚芳醚酮酮的多晶型和晶体结构鉴定
DOI：
--
复制
发表时间：
1996
期刊：
影响因子：
--
通讯作者：
K. Gardner
中科院分区：
文献类型：
--
作者：
Stephen Z. D. Cheng;R. Ho;B. Hsiao;K. Gardner
聚（芳醚酮酮）（PEKK）通过与二苯醚和对苯二甲酸（T）和/或对苯二甲酸（I）的傅-克酰化反应制备。用透射电子显微镜（TEM）、电子衍射（艾德）和广角X射线衍射（WAXD）研究了三种PEKK均聚物的晶体结构、多晶型和形态。所研究的PEKK由所有对亚苯基键[PEKK（T）]、一个间亚苯基键[PEKK（I）]或交替的T和I异构体[PEKK（T/I）]组成。PEKK（T）和PEKK（T/I）根据结晶条件和方法显示结晶多晶型。在PEKK（T）中，可以观察到两种形式（I和II），并且通过艾德实验确定了它们的晶胞尺寸和对称群。这两种形式之间的可能的外延关系，提出当它们共存。PEKK（I）仅具有一个晶体晶胞，其属于与PEKK（T）中的I型结构相同的类别。晶胞的c轴尺寸已被确定为具有锯齿形构象的三个亚苯基，其中间亚苯基位于骨架平面上。PEKK（T/I）具有复杂的多态性。除了I型和II型之外，与PEKK（T）的情况一样，还观察到可能的III型。
Poly(aryl ether ketone ketone)s (PEKKs) are prepared via a Friedel-Crafts acylation reaction with diphenyl ether and terephthalic acid (T) and/or isophthalic acid (I). The crystal structure, polymorphism and morphology of three PEKK homopolymers have been investigated using transmission electron microscopy (TEM), electron diffraction (ED) and wide angle X-ray diffraction (WAXD) experiments. The PEKKs studied consist of either all para-phenylene linkages [PEKK(T)], one meta-phenylene linkage [PEKK(I)] or alternating T and I isomers [PEKK(T/I)]. PEKK(T) and PEKK(T/I) show crystalline polymorphism depending upon the crystallization conditions and methods. In PEKK(T) two forms (I and II) can be observed, and their unit cell dimensions and symmetry groups are determined via ED experiments. A possible epitaxial relationship between these two forms is proposed when they coexist. PEKK(I) possesses only one crystal unit cell which belongs to the same category as the form I structure in PEKK(T). The c-axis dimension of the unit cell has been determined as three phenylenes having a zig-zag conformation, with the meta-phenylene lying on the backbone plane. PEKK(T/I) shows a complicated polymorphism. In addition to forms I and II, as in the case of PEKK(T), a possible form III is also observed.