Columnar Formation from Polyethynylbenzene and Poly-(p-Methylethynylbenzene) Polymerized Using [Rh(norbornadiene)CI]₂as a Catalyst. An X-ray and ESR Study

Spin Glass‐like Behavior of Poly(phenylacetylene) Prepared with a Rh Complex Catalyst, 1

“…However, the reason why the two cusps at 62 K and at 116 K show such different magnetic field dependence can not be clearly explained at present (see Figure 1). It is noteworthy that radical spin concentrations included in this PPA were estimated using electron spin resonance (ESR) method as around 10 16 spins/g at room temperature, although the radicals were rotationally generated through the so-called cis-to-trans isomerization during the polymerization and/or on standing the polymer solution at room temperature [8] as mentioned above. However, the degree of the contribution to the cusps is not clear at present.…”

“…One is the frustration in the magnetic interaction between the magnetic spins involved in the PPA polymer. Previously, we reported that a PPA with a cis-transoid structure is composed of an amorphous part and a helical crystalline part called a pseudohexagonal structure, i.e., p conjugated nano columnar in the solid phase [8,13] and a small amount of p-radicals as unpaired electrons were mainly stabilized in the amorphous part of PPA, [8] whose unpaired electrons were generated through the rotational scission of the cis C C bonds during the polymerization even at room temperature. [4,9,10] Therefore, we may expect ferromagnetic and/or anti-ferromagnetic interaction in the polymer, if such magnetic spins are located between intra-and/or inter-molecular chains and magnetically interact with each other to create some spin assembly as we have reported.…”

“…[4,9,10] Therefore, we may expect ferromagnetic and/or anti-ferromagnetic interaction in the polymer, if such magnetic spins are located between intra-and/or inter-molecular chains and magnetically interact with each other to create some spin assembly as we have reported. [8] The observed weak ferromagnetic hysteresis curve seems to reflect the formation of the so-called canted antiferromagnetic state. [20] Therefore, the observed closed magnetic curve does not reflect the formation of the usual ferromagnetic state but rather, the canted anti-ferromagnetic state as mentioned above.…”

“…The p-radicals, which can be rotationally produced by the cis C C bonds in the aromatic polyacetylene, i.e., poly(phenylacetylene) (PPA) may also be expected to possess stable magnetic spins. [3,4] Previously, we have shown that the highly stereoregular polymerization of phenylacetylene (PA) and its derivatives can be initiated with Rh complex catalysts in the presence of alcohol or triethylamine to produce the PPA polymers that have a high content in the cis-transoid form under quite mild conditions [5][6][7][8] and have revealed a unique magnetic feature of controllability of number of unpaired electrons, e.g., magnetic spins through the so-called cis-to-trans geometrical isomerization. The geometrical isomerization can be induced by thermal treatment, [9] compression, [4,9,10] photo-illumination, [11] and g irradiation, [12] although the thermal isomerization takes place even during polymerization.…”

Columnar Assemblies of Aliphatic Poly(acetylene ester)s Prepared with a [Rh(norbornadiene)Cl]2 Catalyst.1H and13C NMR, X-Ray Diffraction and AFM Studies

“…[13,14] It is also quite important to precisely control the properties of the solid polymers, because the physicochemical properties of the solid polymers are directly governed by the secondary structure, that is, the packing of the polymer chains. However, the control of the solid structure is not easy except for elongation of solid films or strings of polymer, or formation of a superstructure such as a columnar assemblies, found, for example, in poly(phenylacetylene) [15] and poly(p-methylphenylacetylene). [16] Full Paper: Alkyl propiolates: HC3CCOOn-C m H 2m+1 (m = 2l4), acetylene esters were polymerized with a [Rh(norbornadiene)Cl] 2 catalyst in methanol as the polymerization solvent to produce poly(n-alkyl propiolate)s, PAPAs, called polyacetylene esters, in relatively high yields.…”