Complementary Hydrogen-Bonded Thermoreversible Polymer Networks with Tunable Properties

Abstract

Complementary hydrogen bonded cross-linked polymer networks based on two distinct hydrogen bonding recognition motifs have been synthesized by using a combination of ring-opening metathesis polymerization and hydrogen bonding interactions and were subsequently characterized in solution using rheometry. The hydrogen bonding recognition units were based on either three-point cyanuric acid-2,4-diaminotriazine or six-point cyanuric acid-Hamilton wedge interactions. Through the addition of "ditopic cross-linking agents", the polymer scaffold, which was functionalized with cyanuric acid functional groups, was noncovalently cross-linked in solution through complementary interchain hydrogen bonding interactions. The extent of cross-linking could be controlled by varying the amount of the cross-linking agent added. These networks are thermally reversible and have highly tunable mechanical properties that are controlled by the molecular structure of the cross-linking agent. While the addition of the Hamilton wedge cross-linking agent to the polymer solution led to high-viscosity fluids, the 2,4diaminotriazine cross-linking agent produced highly viscoelastic gels. It is hypothesized that this is due to a higher degree of connectivity between the cross-linking agent and the polymer in spite of the inherently weaker hydrogen bonding (three-vs six-point). The study shows that the microstructure plays an important role in the macroscopic mechanical properties of these hydrogen bonded networks in solution. By varying the hydrogen bonding motif, materials with tunable rheological properties were obtained from the same parent polymer backbone. Such a strategy will allow for materials design by tailoring the network microstructure via the molecular architecture of the cross-linking agents.

Effect of Hydrogen Bonding on Linear and Nonlinear Rheology of Entangled Polymer Melts

“…Supramolecular polymers are a broad category of materials that include all polymers whose monomeric units can associate via secondary interactions. These secondary interactions can be due to hydrogen bonding [1][2][3][4][5][6][7] , metal-ligand bonding, 8,9 and/or ionic bonding. [10][11][12][13] Hydrogen bonding is the most common non-covalent reversible interaction employed to create supramolecular polymeric assemblies 3 .…”

Thymine- and Adenine-Functionalized Polystyrene Form Self-Assembled Structures through Multiple Complementary Hydrogen Bonds

“…There is much interest in supramolecular structures based on complementary multiple-hydrogen-bond arrays prepared from synthetic polymers presenting nucleotide bases on their side chains [21][22][23][24][25][26][27][28][29][30][31][32][33][34]. The binding forces in systems featuring multiple hydrogen bonds can be tuned, leading to inter-association equilibrium constants (K A ) ranging from several hundred up to more than 10 6 [21][22][23][24][25][26][27][28][29][30][31][32][33][34].…”

Enhancement of Thermal Stability and Selectivity by Introducing Aminotriazine Comonomer to Poly(Octadecyl Acrylate)-Grafted Silica as Chromatography Matrix

“…In this paper, we introduce the versatility of 2-vinyl-4,6-diamino-1,3,5-triazine (AT) as a co-monomer component in a polymeric phase on silica ( Figure 1). AT is known to be effective for improving the thermal stability of polymers [15] and increasing the strength of hydrogels [16,17]; in addition, it can adsorb DNA through hydrogen bonding interactions [18][19][20][21]. This is the first report demonstrating an increase in the thermal stability of copolymer systems composed of octadecyl acrylate (ODA) and AT due to the co-existence of AT, and the induction of selectivity enhancement for molecular planarity against polyaromatic hydrocarbons in HPLC applications.…”