Enhancing Mechanical Performance of a Polymer Material by Incorporating Pillar[5]arene-Based Host-Guest Interactions

Abstract

Polymer gels have been widely used in the field for tissue engineering, sensing, and drug delivery due to their excellent biocompatibility, hydrophilicity, and degradability. However, common polymer gels are easily deformed on account of their relatively weak mechanical properties, thereby hindering their application fields, as well as shortening their service life. The incorporation of reversible non-covalent bonds is capable of improving the mechanical properties of polymer gels. Thus, here, a poly(methyl methacrylate) polymer network was prepared by introducing host-guest interactions between pillar[5]arene and pyridine cation. Owing to the incorporated host-guest interactions, the modified polymer gels exhibited extraordinary mechanical properties according to the results of the tensile tests. In addition, the influence of the host-guest interaction on the mechanical properties of the gels was also proved by rheological experiments and swelling experiments.

Keywords: host–guest interactions; mechanical performance; pillar[5]arene; polymer gels.

Figure 1

The energy dissipation mechanism of the polymer gel network bearing pillar[5]arene-based host–guest interactions and the chemical structures of G-HG, G-H, and G-G polymer gels.

Figure 2

The synthetic routes used to obtain the G-HG, G-H, and G-G gels.

Figure 3

Photographs of the polymer gels of (a) G-G, (b) G-H, and (c) G-HG during the tensile tests. (d) Stress–strain curves, (e) fracture strain, (f) fracture stress, and (g) toughness of the G-G, G-H, and G-HG polymer gels.

Figure 4

Storage (square) and loss (triangle) moduli versus frequency at different temperatures for the polymer gels (a) G-G, (b) G-H, and (c) G-HG.

Figure 5

Photographs of polymer gels of (a) G-H and G-H’, (b) G-G and G-G’, and (c) G-HG and G-HG’ before and after soaking in CHCl₃ or 25 mM CHCl₃/guest 2 solution, respectively. The circular sheet samples of gels immersed in CHCl₃ were called G-H, G-G, and G-HG, whereas those soaked in 25 mM guest 2/CHCl₃ solution were labeled G-H’, G-G’, and G-HG’, respectively. The square of figure is 1 cm × 1 cm. (d) The difference in the mass swelling ratio of the two samples of G-H, G-G, and G-HG gels.