Dynamic Cross-Linking of Catalytically Synthesized Poly(Aminonorbornenes)

Abstract

Amine-functionalized polymeric materials have a wide variety of applications; however, the preparation of these materials is often plagued by laborious, multistep synthetic routes. Herein, a modified and improved synthetic protocol utilizes the hydroaminoalkylation reaction to catalytically assemble amine-functionalized monomers on a gram scale with 100% atom economy. Combined with ring-opening metathesis polymerization (ROMP), amine-functionalized polymers with varying electronic properties have been synthesized. Extensive rheological characterizations show that modification of the electronic properties of the amine substituent influences the bulk material properties through modification of hydrogen bonding and π-stacking interactions to afford dynamic cross-linking within the polymeric material. Tertiary amine-containing polymers display distinct rheological properties that differ from those of polymers with pendant hydrogen-bond-donating secondary amines. The profound viscoelastic effects that result from the incorporation of tunable dynamic interactions are presented.

Ureate Titanium Catalysts for Hydroaminoalkylation: Using Ligand Design to Increase Reactivity and Utility

“…Recently, we reported the synthesis of secondary amine containing polymers using the tantalum-catalyzed hydroaminoalkylation of dienes and subsequent ring-opening metathesis polymerization (ROMP). , This strategy has opened a new avenue to synthesize amine-functionalized materials with tunable rheological and mechanical properties, and improved methods featuring green, easy to use, and inexpensive titanium catalysts would make these materials more accessible. With our new catalyst we reacted N -methylaniline with norbornadiene (NBD) and 1,5-cyclooctadiene (COD) neat to generate amine-containing monomers 1 (98 mg) and 2 (107 mg), respectively, suitable for subsequent ROMP (Figure a).…”

“…We demonstrate the high reactivity and selectivity for the branched hydroaminoalkylation product through various transformations of unactivated and activated terminal alkenes with alkyl- and arylamines as well as an N-heterocycle. Finally, we feature a reaction procedure that avoids glovebox techniques and we demonstrate its utility in the synthesis of monomers suitable for making N-containing polymers , and the synthesis of building blocks for medicinally relevant amine small molecules.…”

Catalytic Amine Functionalization and Polymerization of Cyclic Alkenes Creates Adhesive and Self-Healing Materials

“…In traditional olefin polymerization using Ziegler–Natta/metallocene-based catalysts, compatibility between the amine-functionalized monomers and the polymerization catalyst remains a long-standing significant challenge. , Postpolymerization modification has been achieved, although these methods lack controlled functional group incorporation and require chemically harsh reaction conditions that often lead to chain scission/branching. , Acyclic diene metathesis (ADMET) is viable; however, multistep protocols including amine protection are required to obtain high-molecular-weight polymers . In recent years, Hillmyer and others have shown that ring-opening metathesis polymerization (ROMP) of prefunctionalized cyclooctene (COE) can be a powerful tool for the controlled synthesis of functionalized polymers. , To date this route with amines has required multistep monomer synthesis, and ROMP has proven incompatible with unprotected 5- or 3-aminated COE monomers. , Meanwhile, recent generations of efficient Mo , and Ru − metathesis catalysts have enabled ROMP with strained amine-functionalized norbornene derivatives.…”

Commodity Polymers to Functional Aminated Materials: Single-Step and Atom-Economic Synthesis by Hydroaminoalkylation

“…Amine-functionalized materials are highly sought after due to their polarity, basicity, and nucleophilicity, allowing them to participate in intermolecular interactions − and reactions with acids and electrophiles. − The incorporation of these features in a polymer can produce active materials that respond to environmental stimuli or be modified to fabricate other functional materials. Amine-containing monomers have been polymerized, but often have relatively low molecular weights and high dispersity. − Furthermore, commercially sourced polyamines are considerably more expensive than PE or PP.…”

“…All materials were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC; Table ). As a result of the mass gained and propensity for dynamic associations through noncovalent interactions after amination, − the temperature of thermal decomposition increased. This is most obvious when comparing VT300 with the AT300 derivatives where the most pronounced impact is seen with AT300-HNMeCy , having an 80 °C increase in thermal stability.…”