Mechanochemically initiated polymerizations. Characterization of poly(acrylonitrile) mechanochemically synthesized by vibratory grinding

Abstract

Mechanical energy which is released by vibratory grinding is able to initiate polymerization reactions of some vinylic monomers. On this way it was possible to obtain poly(acrylonitrile) without any initiator or classical catalyst. The paper presents the physico‐chemical properties of the products obtained by vibratory grinding of acrylonitrile. For the characterization of the obtained polymers, IR‐, ESR‐, and Mössbauer‐spectra were used, together with X‐ray diffraction. Based on the chemical composition and spectral analysis a reaction mechanism and the polymer structure were proposed.

The mechanochemical synthesis of polymers

“…125,138 Continuing studies by Oprea in the 1980s and by Kuzuya in the 1990s covered many of the vinyl monomers known to undergo polymerisation (Scheme 1). 18 The adopted strategy was used to convert (meth)acrylates, 19,130,139–145 (meth)acrylamides, 125,126,141,146 styrenes, 128,141,147–150 and other structurally diverse vinyl monomers 149–152 into the corresponding polymers under solvent-free ball-milling conditions. Moreover, the copolymerisation of these monomers has also been investigated, 125,130,140,149,153–155 as is discussed below.…”

“…, the Oprea group reported that the ball-milling of acrylonitrile produces polyacrylonitrile even without additives. 151,165 All monomers presented in Scheme 1 do not require external initiators for ball-milling polymerisation. Both Oprea and Kuzuya proposed that the initiation step involves electron transfer from the milling material to the substrate.…”

Mechanochemically initiated copolymerizations. 5. Characterization of some binary and ternary copolymers obtained mechanochemically by vibratory milling

“…A part of this calcination residue represents the metal chemically bound in the copolymer structure. For both the acrylonitrile homopolymer [5] and the ternary copolymer [6] the emission and Mossbauer spectral analyses indicated the metal content to be no more than 2% in the soluble fraction. It follows t h a t the chemical structure of the polymer is modified in t h e presence of the metal by forming metallopolymers known t o have a high thermostability [9].…”

“…This fact might be explained by the presence in the polymer structure of t h e metal atoms arising from the milling equipment, iron prevailing among them. This metal was detected and analysed quantitatively by means of Mossbauer spectroscopy [5] and emission spertroscopy [7] in case of the acrylonitrile homopolymer and ternary copolymer (acrylonitrile/vinyl acetatelamethyl styrene) formation.…”