Van Hoorde Jens, Badi Nezha, Du Prez Filip E
Polymer Chemistry Research Group, Centre of Macromolecular Chemistry (CMaC), Department of Organic and Macromolecular Chemistry, Faculty of Sciences, Ghent University Krijgslaan 281 S4 9000 Ghent Belgium
Polym Chem. 2024 Oct 10;15(42):4319-4326. doi: 10.1039/d4py01001a. eCollection 2024 Oct 29.
The full potential of sequence-defined macromolecules remains unexplored, hindered by the difficulty of synthesizing sufficient amounts for the investigation of the properties of such uniform structures and their derived materials. Herein, we report the bidirectional synthesis and thermal behavior analysis of sequence-defined oligourethanes. The synthesis was conducted on a large scale (up to 50 grams) using a straightforward protocol, yielding uniform macromolecules as validated by NMR, ESI-MS and SEC. With this approach, a library of uniform oligourethanes (up to the octamers) was produced using two structural units: a hydrogen-bonding carbamate and a methyl-substituted alternative structure. By varying the chain length, monomer sequence and functionality, we were able to perform a systematic study of the impact of hydrogen bonding on the thermal properties of polyurethanes. Thermal analysis of the discrete oligomers using DSC revealed that both the molecular weight and microstructure significantly affect the glass transition and melting temperatures. TGA measurements also revealed differences in the thermal stability of the oligomers, underscoring the significance of the primary structure of polyurethanes. Additionally, the influence of the terminal groups on the degradation pathway was assessed pyrolysis-GC-MS, which specifically highlighted the increased thermal stability in the absence of hydroxyl end groups. This work shows the interest of using sequence-defined synthetic macromolecules for the elucidation of structure-property relationships and thereby facilitates their fine-tuning towards specific material applications.
序列定义的大分子的全部潜力仍未得到充分探索，这受到合成足够量以研究此类均匀结构及其衍生材料性质的困难的阻碍。在此，我们报告了序列定义的寡聚脲烷的双向合成及热行为分析。合成采用简单的方案大规模进行（高达50克），通过核磁共振（NMR）、电喷雾电离质谱（ESI-MS）和尺寸排阻色谱（SEC）验证，得到了均匀的大分子。通过这种方法，使用两个结构单元：氢键氨基甲酸酯和甲基取代的替代结构，制备了一个均匀寡聚脲烷文库（高达八聚体）。通过改变链长、单体序列和官能度，我们能够对氢键对聚氨酯热性能的影响进行系统研究。使用差示扫描量热法（DSC）对离散寡聚物进行热分析表明，分子量和微观结构均显著影响玻璃化转变温度和熔点。热重分析（TGA）测量还揭示了寡聚物热稳定性的差异，突出了聚氨酯一级结构的重要性。此外，通过热解气相色谱-质谱联用（pyrolysis-GC-MS）评估了端基对降解途径的影响，特别强调了在没有羟基端基时热稳定性的提高。这项工作表明了使用序列定义的合成大分子来阐明结构-性能关系的意义，从而有助于针对特定材料应用对其进行精细调整。
