Molecular Oxygen Insertion Polymerization into Crystals of Tetrakis(alkoxycarbonyl)quinodimethanes

Abstract

Solid-state alternating copolymerization took place by molecular oxygen insertion in the crystals of 7,7,8,8-tetrakis(ethoxycarbonyl)quinodimethane (1a) and 7,7-bis(ethoxycarbonyl)-8,8-bis-(methoxycarbonyl)quinodimethane (1b) to form highly crystalline needlelike white solids for 1a and amorphous ones for 1b. The polymer structures were confirmed by 1 H NMR, 13 C NMR, IR, elemental analysis, powder XRD, and TGA measurements. However, in vacuo polymerizations of 1a and 1b in the solid state with heating and photoirradiation did not take place. 7,7,8,8-Tetrakis(methoxycarbonyl)-quinodimethane (1c) did not undergo solid-state alternating copolymerization with oxygen even in the presence of oxygen, but instead it homopolymerized to form highly crystalline homopolymer. The difference in the solid-state polymerization reactivity was discussed on the basis of molecular packing in the crystals obtained by X-ray crystallography. In addition, it was found by ESR measurement that the solid-state alternating copolymerizations with molecular oxygen proceed by means of a radical mechanism. IntroductionSolid-state polymerization implies that polymerization proceeds starting from bulk monomer crystals, and it has been divided into two classes: topotactic and topochemical polymerizations. 1 The former is the polymerization that provides a polymer with a specific crystal structure formed under control of the crystal lattice of the monomer, and the latter is the polymerization that proceeds with no movement of the center of gravity of the monomer molecule and only slight rotation of the monomer molecule around the gravity; that is, the crystallographic position and symmetry of the monomer crystals are retained in the resulting polymer crystals. Therefore, topochemical polymerization is a promising method to obtain polymers with highly controlled structures. A limited number of monomers such as derivatives of diacetylene, 1 2,5-distyrylpyrazine, 2 triene and triacetylene, 3 muconic acid and sorbic acid, 4 and 7,7,8,8-tetrakis(alkoxycarbonyl)quinodiemthane 5 have been reported to undergo topochemical polymerizations, and they are known to have strict requirements of the monomer arrangements in the crystals. However, it is still difficult to predict and control the polymerization properties of compounds in the crystals because arrangements of monomers play a significant role. Further investigation of the crystal structures of monomers related with solid-state polymerizations should enable us to control the reactivities of the monomers and provide us models for the reaction pathway of the polymerization reactions.

Solution-processable and functionalizable ultra-high molecular weight polymers via topochemical synthesis

“…After polymerization, crystals of P1 and P2 become insoluble, while those of P3 readily dissolve in many common mid-range polarity organic solvents. In contrast to previously reported TCP systems—including the closely related substituted para -quinodimethanes and quinone methides—the solid-state reactivity of diphenylidine-substituted AQMs were surprisingly forgiving to the inclusion of long alkyl groups 9 , 35 , 36 , 40 , 41 . Additionally, unlike many other methods of producing UHMW polymers, this method is insensitive to the presence of water and oxygen and requires no catalysts or auxiliaries 54 – 57 .…”

“…1 and Supplementary Fig. 3 , and Supplementary Movie 1 ) 9 , 35 , 41 . The solid-state reactivity of the phenyl-substituted AQM monomers 1 – 3 differs from the monomer 4 , which is not affected by light and/or heat.…”

Polymers with advanced structural and supramolecular features synthesized through topochemical polymerization

“…11b ), also copolymerizes with oxygen to form an alternating copolymer. 58 However, the copolymer obtained from 43 is amorphous. A larger stacking distance (5.11 Å) and/or a larger distance between the reactive exomethylene carbons (5.11 Å) could have necessitated significant molecular movement and resulted in the loss of crystallinity.…”

The effect of various catalysts on the monomer reactivity ratios in oxidative copolymerization of styrene and α‐methylstyrene

“…This class of polymers are gaining significant importance due to their applications as polymeric initiators for the radical polymerization of vinyl monomers, autocombustible fuel, dismantlable adhesion, etc. Radical copolymerizations of 1,3‐diene monomers, dibenzofulvene, 7,7,8,8‐tetrakis(ethoxycarbonyl)quinodimethane and related monomers with oxygen have also been carried out to prepare alternating copolymers consisting repeat peroxy units in the polymer backbone. In the literature, most vinyl polyperoxides have been synthesized by 2,2′‐azobisisobutyronitrile (AIBN)‐initiated polymerization of vinyl monomers and oxygen at or above 50 °C .…”