Fully Isotactic Poly(p-methylstyrene): Precise Synthesis via Catalytic Polymerization and Crystallization Studies,Macromolecules

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Fully Isotactic Poly(p-methylstyrene): Precise Synthesis via Catalytic Polymerization and Crystallization Studies
Macromolecules ( IF 5.1 ) Pub Date : 2019-06-19 00:00:00 , DOI: 10.1021/acs.macromol.9b00640
Tianyu Wu ₁ , Luis Valencia _{2,

3} , Thomas Pfohl ₁ , Barbara Heck ₁ , Günter Reiter _{1,

4,

5} , Pierre J. Lutz _{2,

3} , Rolf Mülhaupt _{2,

4,

5}

Affiliation

The synthesis of stereoregular styrenic polymers on single-site catalysts has received great attention over the last decades; however, little is known with respect to tailoring fully isotactic poly(p-methylstyrene) (iPpMS). Here, we demonstrate that isospecific coordination polymerization of p-methylstyrene can be achieved in the presence of the catalyst dichloro[1,4-dithiabutanediyl-2,20-bis(4,6-di-tert-butyl-phenoxy)]titanium activated by methylaluminoxane. Moreover, iPpMS has been assumed to be noncrystallizable for decades, as X-ray diffraction and differential scanning calorimeter measurements of powder samples failed to reveal a well-defined crystal structure. However, we successfully generated dendritic crystals of iPpMS from dilute solutions by carefully controlling the evaporation rate of the solvent. The crystal morphology was studied by optical microscopy and atomic force microscopy. In situ heating experiments of dendritic crystals allowed us to measure the melting temperature of iPpMS crystals. Moreover, a vapor annealing process was carried out to prepare multilamellar crystals for small-angle X-ray scattering measurements to characterize the spacing and orientation of the formed crystalline lamellae.

中文翻译：

全同立构聚对甲基苯乙烯：通过催化聚合和结晶研究精确合成

在过去的几十年中，在单中心催化剂上合成立构规整的苯乙烯聚合物受到了极大的关注。然而，关于定制完全等规的聚（对甲基苯乙烯）（iP p MS）知之甚少。在这里，我们证明了的全同有择配位聚合p甲基苯乙烯可以在催化剂二氯[1,4- dithiabutanediyl-2,20 -双（4,6-二叔的存在来实现-叔丁基-苯氧基）]钛活化由甲基铝氧烷。而且，iP p由于粉末样品的X射线衍射和差示扫描量热法测量未能显示出明确定义的晶体结构，因此数十年来人们一直认为MS是不可结晶的。但是，我们通过小心控制溶剂的蒸发速率，成功地从稀溶液中生成了iP p MS的树枝状晶体。通过光学显微镜和原子力显微镜研究了晶体形态。树枝状晶体的原位加热实验使我们能够测量iP p MS晶体的熔化温度。此外，进行了蒸气退火工艺以制备用于小角度X射线散射测量的多层晶体，以表征形成的晶体层的间隔和取向。

更新日期：2019-06-19

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