Solvent‐Free Mechanochemical Post‐Polymerization Modification of Ionic Polymers

Abstract

Despite their superior stability and facile handling, ionic polymers have limited solubility in most organic solvents, restricting the range of substrates and reaction conditions to which they can be applied. To overcome this solubility issue, the present study presents a solvent‐free mechanochemical reaction. Specifically, a post‐polymerization modification of ammonium‐functionalized polyether was demonstrated using a solvent‐free vibrational ball‐milling technique. The formation of imine bonds between the ionic polymer and an aromatic aldehyde led to the complete conversion to imine within 1 h without any bond breakage on the polymer backbone. The viability of this approach for a wide range of aldehydes was also evaluated, highlighting the potential of the mechanochemical post‐polymerization modification of polymers that are inaccessible by conventional solution approaches.

The mechanochemical synthesis of polymers

“…In a further approach Kim and Kim additionally verified that the immiscibility is indeed not a limiting factor for mechanochemical post-polymerization modifications, as they achieved the conjugation of hydrophobic molecules and an ionic polymer, poorly soluble in organic solvents, by ball milling. 207 Fig. 11 Schematic mechanochemical transformation of chitin to chitosan.…”

Disentangling the Effect of Pressure and Mixing on a Mechanochemical Bromination Reaction by Solid‐State NMR Spectroscopy**

“…The influence of mechanical forces on chemical reactions has attracted chemists for many decades, for instance, due to the possibility of opening alternative synthetic pathways otherwise unachievable using different means of energetic input, such as light and temperature. [1][2][3][4] The field of mechanochemistry 5 has experienced enormous advances in the past years, reflected in versatile chemical and biological applications (for selected reviews see [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] ), ranging from the solid-state synthesis of inorganic materials, [24][25][26][27] metal-organic [28][29][30][31][32] and organic compounds, [33][34][35][36] covalent organic frameworks, 37 and polymers [38][39][40][41][42][43] to enzymatic reactions 19,[44][45]…”

Mechanochemical Synthesis of Fluorinated Imines

“…Mechanochemical methodologies offer advantages over conventional synthetic routes with regard to the amount of solvents used and the energy consumed, and provide more efficient organic waste management; thus, they are becoming popular techniques for organic synthesis [ 23 , 24 , 25 ]. The preparation of imines by the mechanochemical approach has already been reported [ 26 , 27 , 28 , 29 , 30 ]. Synthetic protocols required the use of mills [ 27 , 28 , 29 , 30 ], catalytic amounts of iodine [ 27 ], workup of the obtained products [ 27 , 28 ] and long milling times (60 [ 30 ] or 90 [ 28 ] min).…”

“…The preparation of imines by the mechanochemical approach has already been reported [ 26 , 27 , 28 , 29 , 30 ]. Synthetic protocols required the use of mills [ 27 , 28 , 29 , 30 ], catalytic amounts of iodine [ 27 ], workup of the obtained products [ 27 , 28 ] and long milling times (60 [ 30 ] or 90 [ 28 ] min). Regarding the fluorine-containing imines, we found only one study on the mechanochemical strategy used for the synthesis of such compounds.…”