A Supramolecular Polymer Blend Containing Two Different Supramolecular Polymers through Self‐Sorting Organization of Two Heteroditopic Monomers

Abstract

The creation of complex and highly-ordered structures with desired properties and novel functions has been fundamental to supramolecular chemistry and material science, and plays an essential role in high-tech and biorelated fields, such as drug delivery systems, molecular devices and photovoltaic applications. Nature, as the best example of precise and efficient self-assembly processes, promotes chemists to engage in developing highly-ordered artificial supramolecular assemblies, such as supramolecular polymers through the utilization of noncovalent interactions. Held together by reversible and highly dimensional interactions, such as host–guest interactions, hydrogen bonds, and metal coordination, supramolecular polymers have become one of the most active frontiers in the past two decades and have received a great deal of attention. Compared with conventional polymers, supramolecular polymers typically show many dynamic or precisely controllable properties arising from dynamic linking between the constituent monomers and have the ability to respond to their environment as adaptive materials. The interest in supramolecular polymers has expanded in recent years, not only for their potential properties as functional materials, but also for their intriguing architectures and topologies that act as a basic aspect of potential applications. The simple blending of different polymers has produced new polymer blend materials with controllable and unique properties. Polymer blends have been widely studied in polymer chemistry and materials science, and as such supramolecular polymer blends, defined as mixtures of two or more different and mutually exclusive supramolecular polymers, are an attractive topic. There are beautiful examples of miscible polymer blends based on either multiple hydrogen-bonding, p-stacking, carboxy–amine interactions, or crown ether functionlized polymers with ammoniumor paraquat-functionalized polymers. However, these blends were composed of high-molecular-weight, conventional covalently bonded polymers instead of noncovalently connected supramolecular polymers. It is still a big challenge for chemists to design and prepare supramolecular polymer blends completely from low-molecularweight monomers without any conventional polymeric backbones. Self-sorting systems, whereby different molecules or molecular aggregates can assemble themselves with corresponding recognition units, display a critical ability to efficiently distinguish between different recognition units even in a complex mixture or in a system with similar recognition units. For example, Harada et al. found that multiple noncovalent interactions including hydrophobic interactions, p– p stacking and hydrogen-bonding interactions can create a social-self-sorting system cooperatively. Crown ethers, as the first generation of supramolecular macrocyclic hosts, have been widely used as building blocks to construct various functional assemblies with different guest molecules. Based on the differences in binding affinity and binding selectivity between two crown ethers, dibenzo[24]crown-8 (DB24C8) and bis(p-phenylene)[34]crown-10 (BPP34C10), and their complementary guest moieties, dibenzylammonium salts (DBA) and paraquat derivatives, our group has successfully prepared an alternating supramolecular polymer by means of the self-sorting organization of two AB-type heteroditopic monomers. It is of considerable interest to investigate whether it is possible to combine a binary system consisting of a pair of supramolecular polymers through a self-sorting process into a supramolecular polymer blend from low-molecular-weight monomers. For example, if a supramolecular polymer gel is blended with a linear supramolecular polymer, the gelation and other properties of the supramolecular polymer gel can be tuned. Herein we report on a supramolecular polymer blend, which is formed due to the self-sorting organization of two heteroditopic AB-type monomers, 1 and 2 (Scheme 1). Monomer 1 has a DB24C8 moiety and a DBA group, which are linked together by a long and flexible alkyl chain. Monomer 2 contains a BPP34C10-paraquat-based analogue and has [a] S. Dong, X. Yan, B. Zheng, J. Chen, M. Zhang, Prof. Dr. F. Huang Department of Chemistry, Zhejiang University Hangzhou, Zhejiang 310027 (P.R. China) Fax: (+86)571-87953189 E-mail : fhuang@zju.edu.cn [b] X. Ding, Prof. Dr. Y. Yu Shanghai Key Laboratory of Magnetic Resonance Department of Physics, East China Normal University Shanghai 200062 (P.R. China) [c] Dr. D. Xu Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 (P. R. China) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201200016.