Department of Chemistry , Indiana University , 800 East Kirkwood Avenue , Bloomington , Indiana 47405 , United States.
School of Polymer Science and Engineering , The University of Southern Mississippi , 118 College Drive , Hattiesburg , Mississippi 39406 , United States.
J Am Chem Soc. 2020 Feb 5;142(5):2579-2591. doi: 10.1021/jacs.9b12645. Epub 2020 Jan 24.
Sequence-controlled supramolecular polymers offer new design paradigms for generating stimuli-responsive macromolecules with enhanced functionalities. The dynamic character of supramolecular links present challenges to sequence definition in extended supramolecular macromolecules, and design principles remain nascent. Here, we demonstrate the first example of using stoichiometry-control to specify the monomer sequence in a linear supramolecular polymer by synthesizing both a homopolymer and an alternating copolymer from the same glycol-substituted cyanostar macrocycle and phenylene-linked diphosphate monomers. A 2:1 stoichiometry between macrocycle and diphosphate produces a supramolecular homopolymer of general formula () comprised of repeating units of cyanostar-stabilized phosphate-phosphate dimers. Using a 1:1 stoichiometry, an alternating () structure is produced with half the phosphate dimers now stabilized by the additional counter cations that emerge hierarchically after forming the stronger cyanostar-stabilized phosphate dimers. These new polymer materials and binding motifs are sufficient to bear normal and shear stress to promote significant and tunable adhesive properties. The homopolymer (), consisting of cyanostar-stabilized -electrostatic linkages, shows adhesion strength comparable to commercial superglue formulations based on polycyanoacrylate but is thermally reversible. Unexpectedly, and despite including traditional ionic linkages, the alternating copolymer () shows weaker adhesion strength more similar to commercial white glue based on poly(vinyl acetate). Thus, the adhesion properties can be tuned over a wide range by simply controlling the stoichiometric ratio of monomers. This study offers new insight into supramolecular polymers composed of custom-designed anion and receptor monomers and demonstrates the utility of emerging functional materials based on anion-anion linkages.
序列控制的超分子聚合物为生成具有增强功能的刺激响应性大分子提供了新的设计范例。超分子键的动态特性对扩展超分子大分子中的序列定义提出了挑战，而设计原则仍处于起步阶段。在这里，我们通过使用化学计量控制来合成同一乙二醇取代的氰星大环和苯并二磷酸盐单体的均聚物和交替共聚物，证明了在线性超分子聚合物中使用化学计量控制来指定单体序列的第一个例子。大环和二磷酸盐之间的 2:1 化学计量比产生了具有通式（）的超分子均聚物，其中包含氰星稳定的磷酸盐-磷酸盐二聚体的重复单元。使用 1:1 的化学计量比，可以产生交替的（）结构，其中现在有一半的磷酸盐二聚体由额外的抗衡离子稳定，这些抗衡离子在形成更强的氰星稳定的磷酸盐二聚体后分层出现。这些新的聚合物材料和结合基序足以承受正常和剪切应力，以促进显著且可调节的粘附性能。均聚物（）由氰星稳定的-静电键合组成，其粘附强度可与基于聚氰基丙烯酸酯的商业超级胶水制剂相媲美，但具有热可逆性。出乎意料的是，尽管包含传统的离子键，但交替共聚物（）的粘附强度较弱，与基于聚（醋酸乙烯酯）的商业白胶更为相似。因此，通过简单控制单体的化学计量比，可以在很宽的范围内调节粘附性能。这项研究为基于定制设计的阴离子和受体单体组成的超分子聚合物提供了新的见解，并展示了基于阴离子-阴离子键的新兴功能材料的实用性。
