Intramolecular and Intermolecular Packing in Polymer Crystallization

聚合物结晶中的分子内和分子间堆积

• 批准号: 2004393
• 负责人: Toshikazu Miyoshi
• 金额: $ 59.4万
• 依托单位: University of Akron
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2004393&HistoricalAwards=false
• 关键词: Intramolecular; Intermolecular; Packing; Polymer; Crystallization

PART 1: NON-TECHNICAL SUMMARYMore than 2/3 of all commercially available polymers are semicrystalline including an enormous number and variety of materials in our lives as well as in all kinds of high-technology applications. Tuning of polymer crystallization through the macromolecular chain structures or through high-order structural assemblies has been improved over the last half century. However, a fundamental problem of widespread importance is to understand the mechanism of polymer crystallization at the molecular level. Many factors, such as molecular entanglement, mobility, molecular weight, solvent-polymer or polymer-polymer interactions, polymer concentration, and others influence the chain-level structure of semicrystalline polymers during crystallization. This project is aimed at characterizing intramolecular and intermolecular structures of specially labeled semicrystalline polymers in crystals grown from the melt or from solution. The research is expected to enhance foundations about: (i) entanglement effects on chain-folding structure in melt-grown crystals, (ii) molecular weight effects on chain-folding motif in single crystals, (iii) early stage of polymer crystallization in dilute solutions, (iv) chiral recognition of helical polymers, and (v) molecular dynamics of stereoregular polyolefin-type materials. The established foundations will be important for understanding crystallization mechanisms and for designing novel polymer materials. Graduate students trained in this project will acquire broad experimental skills covering polymer synthesis, materials characterization, advanced NMR characterization, and numerical simulations. They will have opportunities to present technical talks and posters at national and regional meetings. PART 2: TECHNICAL SUMMARYLong and flexible semicrystalline polymers fold to various extents during crystallization. Folding generates intramolecular packing in addition to intermolecular packing. Understanding of intramolecular and intermolecular packing structures is essential in the crystallization process of long polymer chains. This project will focus on evaluation of the intramolecular and intermolecular packing structures of 13C labeled semicrystalline polymers in solution and melt-grown crystals by using nuclear magnetic resonance (NMR) spectroscopy. A biodegradable polymer, poly(lactic acid) (PLA) will be used as a model system, since established decomposition route allows us to re-use 13C labeled monomer to effectively synthesize a variety of 13C labeled PLAs with precisely controlled and diverse molecular weights from 2K to over 100K g/mol. First, the project is aimed at entanglement effects on the intramolecular packing structure of poly(L-lactic acid) by investigating (i) Mw effect on the chain-folding structure and (ii) blending effect of low Mw component on the chain-folding structure of long chains in melt-grown crystals. A second thrust aims at elucidating (i) Mw effect on the molecular dimension of the folded chains in solution-grown crystals and (ii) precursor structure in dilute solutions. Recently developed Dynamic Nuclear Polarization NMR significantly enhances sensitivity of the 13C labeled polymer signals (~ 400 times) and thus may allow to directly analyze the chain-level structure of 13C labeled polymer in the frozen solution state. This experiment will shed light on the early stage of polymer crystallization at the molecular level. A third thrust aims at understanding the importance of both intermolecular and intramolecular packing on polymer crystallization. A model system of PLA stereocomplex will be used to address Mw effects on both intramolecular and intermolecular packing structures. Finally, detailed molecular dynamics and mechanical properties of recently developed polyolefins will be explored.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

第一部分：超过2/3的商业可用的聚合物是半结晶的，包括我们生活中以及各种高科技应用中的大量和各种材料。在过去的半个世纪里，通过大分子链结构或通过高阶结构组装来调节聚合物结晶已经得到了改进。 然而，一个具有广泛重要性的基本问题是在分子水平上理解聚合物结晶的机理。 许多因素，如分子缠结、迁移率、分子量、溶剂-聚合物或聚合物-聚合物相互作用、聚合物浓度等影响结晶过程中半结晶聚合物的链级结构。 该项目旨在表征从熔体或溶液中生长的晶体中的特别标记的半结晶聚合物的分子内和分子间结构。该研究有望为以下方面奠定基础：（i）熔融生长晶体中链折叠结构的缠结效应，（ii）单晶中链折叠基序的分子量效应，（iii）稀溶液中聚合物结晶的早期阶段，（iv）螺旋聚合物的手性识别，以及（v）有规立构聚烯烃型材料的分子动力学。所建立的基础对于理解结晶机理和设计新型聚合物材料将是重要的。在这个项目中培训的研究生将获得广泛的实验技能，包括聚合物合成，材料表征，先进的NMR表征和数值模拟。他们将有机会在国家和区域会议上发表技术演讲和海报。 第2部分：技术概述长而柔性的半结晶聚合物在结晶过程中折叠到不同程度。除了分子间堆积之外，折叠还产生分子内堆积。分子内和分子间的堆积结构的理解是必不可少的长链聚合物的结晶过程。该项目将侧重于通过使用核磁共振（NMR）光谱法评估13 C标记的半结晶聚合物在溶液和熔融生长晶体中的分子内和分子间堆积结构。一种可生物降解的聚合物，聚（乳酸）（PLA）将被用作模型系统，因为建立的分解路线允许我们重复使用13 C标记的单体，以有效地合成各种13 C标记的PLA，具有精确控制和不同的分子量从2K到超过100 K g/mol。首先，该项目旨在通过研究（i）Mw对链折叠结构的影响和（ii）低Mw组分对熔融生长晶体中长链的链折叠结构的共混效果，来研究缠结对聚（L-乳酸）分子内堆积结构的影响。 第二个推力旨在阐明（i）Mw对溶液生长晶体中折叠链的分子尺寸的影响和（ii）稀溶液中的前体结构。最近开发的动态核极化NMR显着提高了13 C标记的聚合物信号的灵敏度（~ 400倍），因此可以直接分析13 C标记的聚合物在冷冻溶液状态下的链级结构。该实验将在分子水平上揭示聚合物结晶的早期阶段。第三个推力旨在了解聚合物结晶的分子间和分子内包装的重要性。聚乳酸立体复合物的模型系统将用于解决分子量对分子内和分子间堆积结构的影响。最后，详细的分子动力学和最近开发的聚烯烃的机械性能将explored.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

项目成果

Stochastic Bullvalene Architecture Modulates Structural Rigidity in π‐Rich Macromolecules

随机 Bullvalene 结构调节富大分子的结构刚度

• DOI: 10.1002/anie.202301695
• 发表时间: 2023
• 期刊: Angewandte Chemie International Edition
• 作者: Pomfret, Meredith N.;Sun, Peiguan B.;Huang, Zheng;Freund, Anna C.;Miyoshi, Toshikazu;Golder, Matthew R.
• 通讯作者: Golder, Matthew R.

Roles of Conformational Flexibility in the Crystallization of Stereoirregular Polymers

构象灵活性在立体不规则聚合物结晶中的作用

• DOI: 10.1021/acs.macromol.1c00888
• 发表时间: 2021
• 期刊: Macromolecules
• 影响因子: 5.5
• 作者: Kafle, Navin;Makita, Yuta;Zheng, Ying;Schwarz, Derek;Kurosu, Hiromichi;Pan, Pengju;Eagan, James M.;Nakama, Yuki;Hayano, Shigetaka;Miyoshi, Toshikazu
• 通讯作者: Miyoshi, Toshikazu

Polymer Chains Fold Prior to Crystallization

• DOI: 10.1021/acsmacrolett.1c00789
• 发表时间: 2022-03-15
• 期刊: ACS MACRO LETTERS
• 影响因子: 7.015
• 作者: Jin, Fan;Yuan, Shichen;Miyoshi, Toshikazu
• 通讯作者: Miyoshi, Toshikazu

Asymmetric Molecular Dynamics and Anisotropic Phase Separation in the Cocrystal of the Crystalline/Crystalline Polymer Blend

结晶/结晶聚合物共混物共晶中的不对称分子动力学和各向异性相分离

• DOI: 10.1021/acsmacrolett.1c00745
• 发表时间: 2022
• 期刊: ACS Macro Letters
• 影响因子: 7.015
• 作者: Zheng, Ying;Kafle, Navin;Schwarz, Derek;Eagan, James M.;Hayano, Shigetaka;Nakama, Yuki;Pan, Pengju;Miyoshi, Toshikazu
• 通讯作者: Miyoshi, Toshikazu