A Tetragonal Phase Self-Organized from Unimolecular Spheres Assembled from a Substituted Poly(2-oxazoline)

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• 作者：Marian N. Holerca ; Dipankar Sahoo ; Mihai PetercaBenjamin E. Partridge ; Paul A. HeineyVirgil Percec
• 刊名：Macromolecules
• 出版年：2017
• 出版时间：January 10, 2017
• 年：2017
• 卷：50
• 期：1
• 页码：375-385
• 全文大小：1004K
• ISSN：1520-5835

文摘

Synthesis and living cationic ring-opening polymerization of a 2-oxazoline containing self-assembling minidendrons with hexadecyl groups are reported. Structural analysis using X-ray diffraction, molecular modeling, and reconstructed electron density maps revealed multiple self-organized periodic arrays, including columnar hexagonal P6mm, cubic Pm3̅n, and tetragonal P4₂/mnm phases, which have not been observed before in a single homopolymer. The degree of polymerization (DP) of the poly(2-oxazoline) programs the sequence of these periodic arrays. The cubic Pm3̅n phase was observed for DP = 5 whereas the tetragonal P4₂/mnm for 10 ≤ DP ≤ 50. For DP ≥ 75, only a columnar hexagonal P6mm phase was accessible because the polymer chains are too long to form a single supramolecular sphere. This sequence was rationalized by the columnar character of supramolecular spheres to provide the richest diversity of structures assembled from a single polymer and an unprecedented example of a tetragonal phase organized from macromolecular spheres comprising a single polymer chain.