Stereocomplexes of Discrete, Isotactic Lactic Acid Oligomers Conjugated with Oligodimethylsiloxanes

Macromolecules
Brigitte A G LamersE W Meijer

Abstract

Discrete length block co-oligomers (BCOs) comprised of a crystalline and an amorphous block are a new class of materials that gives highly ordered lamellar morphologies at small length scales. Here, we show the preparation of discrete, isotactic oligo l- and d-lactic acid (olLA and odLA) homoblocks followed by ligation to oligodimethylsiloxane (oDMS), affording a library of crystalline-amorphous BCOs that vary in molecular weight and composition. Mixing the two enantiomeric BCOs or homoblocks results in the formation of the corresponding stereocomplex. The properties and phase behavior of the isotactic (block co)oligomers and the stereocomplexes thereof are studied using differential scanning calorimetry and small-angle X-ray scattering. A systematic study of the isotactic homoblock lengths and crystal structure confirmed the formation of a 103 helix with a monomeric rise of 0.3 nm, whereas the stereocomplex adopts a 31 helix. The same type of crystal structure was found for the isotactic and stereocomplex of BCOs giving rise to the formation of lamellar morphologies at room temperature as a result of crystallization of the oLA blocks. Distorted lamellar structures were found in BCOs that preorganize into nonlamellar morphologi...Continue Reading

References

Jan 1, 1968·Biopolymers·P De Santis, A J Kovacs
Aug 20, 2005·Science·Craig J Hawker, Karen L Wooley
Jul 14, 2016·Journal of the American Chemical Society·Yivan JiangJeremiah A Johnson
Oct 11, 2017·Journal of the American Chemical Society·Bas van GenabeekE W Meijer
Apr 17, 2018·ACS Nano·Qile P ChenJ Ilja Siepmann

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Citations

Feb 3, 2021·Chemical Communications : Chem Comm·Lishan LiXiulin Zhu
Apr 9, 2021·Chemistry : a European Journal·Ming-Sheng JiZi-Hao Guo
Sep 5, 2019·Journal of the American Chemical Society·Brigitte A G LamersE W Meijer
Aug 29, 2019·Journal of the American Chemical Society·Zhao-Qian WanXiao-Bing Lu
Sep 2, 2021·JACS Au·Zhongguo LiuXue-Hui Dong

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Methods Mentioned

BETA
differential scanning calorimetry
X-ray

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