Backbone Polarity Tunes Sticker Clustering in Hydrogen-Bonded Supramolecular Polymer Networks,Macromolecules

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Backbone Polarity Tunes Sticker Clustering in Hydrogen-Bonded Supramolecular Polymer Networks
Macromolecules ( IF 5.1 ) Pub Date : 2022-06-24 , DOI: 10.1021/acs.macromol.2c00645
Mostafa Ahmadi ₁ , Amir Jangizehi ₁ , Sebastian Seiffert ₁

Affiliation

Many of the fascinating properties of natural materials emerge upon phase separation and clustering. However, biomimetic polymeric materials often demonstrate limited performances due to ignoring that hierarchy. Thus, there is a need to change the design paradigm from the simple integration of transient bonds to the engineering of structural hierarchy. To account for that, we develop an entangled hydrogen-bonded supramolecular polymer network, based on strong fourfold hydrogen-bonding ureidopyrimidinone (UPy) groups and poly(n-butyl acrylate) chains, where the local polarity is systematically varied by incorporating free hydroxyl (OH) groups. The integration of UPy groups significantly changes the relaxation spectrum, from a standard Maxwellian terminal flow to a high-frequency plateau spanning over three decades and the emergence of an additional low-frequency plateau. The absence of first-order thermal transitions in DSC curves and the emergence of diffraction peaks at nanometer lengths in SAXS profiles imply the presence of unordered aggregates. The introduction of free OH groups, however, gradually removes the plateau at low frequencies and increases the high-frequency one. A basic tube-based model including the sticky Rouse and the contour length fluctuations that are hindered by a mean-field penalty is developed to explain relaxation steps of entangled chains in the presence of binary associations and their clustering. The obtained fit parameters provide a precious quantitative correlation between the structural characteristics and key material functions. Specifically, despite the UPy content increases the penalty of chain dynamics, the fraction of OH groups does not, due to the countereffects of promoting binary associations and reducing clustering.

中文翻译：

主干极性调整氢键超分子聚合物网络中的贴纸聚类

天然材料的许多迷人特性在相分离和聚集时出现。然而，由于忽略了这种层次结构，仿生聚合物材料通常表现出有限的性能。因此，需要将设计范式从简单的瞬态键集成转变为结构层次的工程。为了解决这个问题，我们开发了一种纠缠的氢键超分子聚合物网络，该网络基于强四重氢键脲基嘧啶酮 (UPy) 基团和聚 ( n-丙烯酸丁酯）链，其中局部极性通过加入游离羟基（OH）基团而系统地变化。UPy 基团的整合显着改变了弛豫谱，从标准的麦克斯韦终端流到跨越三个十年的高频平台，并出现了额外的低频平台。DSC 曲线中没有一级热跃迁，并且 SAXS 曲线中出现纳米长度的衍射峰意味着存在无序聚集体。然而，游离 OH 基团的引入逐渐消除了低频的平台并增加了高频的平台。开发了一个基本的基于管的模型，包括粘性 Rouse 和受平均场惩罚阻碍的轮廓长度波动，以解释在存在二元关联及其聚类的情况下纠缠链的松弛步骤。获得的拟合参数在结构特征和关键材料功能之间提供了宝贵的定量相关性。具体来说，尽管 UPy 含量增加了链动力学的惩罚，但 OH 基团的比例不会，因为促进二元关联和减少聚类的反作用。

更新日期：2022-06-24

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