A novel, highly selective photocyclic aromatization (SCAT) of π-conjugated polymers from phenylacetylene having two hydroxyl groups to exclusively yield a 1,3,5-trisubstituted benzene derivative was developed, and its success was confirmed by (1)H NMR, GPC, and TOF-MS. The SCAT reaction has many unique characteristics. (1) It is a quantitative reaction: it gave only the corresponding cyclic trimer, i.e., a 1,3,5-trisubstituted benzene derivative, quantitatively (100%). No byproducts were produced under the best conditions. (2) It is an intramolecular reaction: it occurred between three adjacent monomer units in one macromolecule. (3) It is a stereospecific and topochemical or template reaction: the reactivity strongly depended on the configuration and conformation of the starting polymer substrates. (4) It is a photoreaction: high selectivity (100%) was observed only by the use of visible light irradiation, not by heating. (5) It is a solid-state reaction: high selectivity (100%) was observed only in the solid state, not in solution. In addition, (6) the resulting cyclic trimers could form a self-supporting membrane, despite their low molecular weights. This new approach resulted in a new class of supramolecular polymers consisting of a 1,3,5-trisubstituted benzene derivative, numbers of which were linearly linked by hydrogen bonds and stacked benzene derivatives. Since SCAT has such high selectivities and is useful for the preparation of a self-supporting supramolecular polymer membrane, many applications can be expected.

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To study the possibility of living cationic polymerization of vinyl ethers with a urethane group, 4‐vinyloxybutyl n‐butylcarbamate (1) and 4‐vinyloxybutyl phenylcarbamate (2) were polymerized with the hydrogen chloride/zinc chloride initiating system in methylene chloride solvent at −30 °C ([monomer]0 = 0.30 M, [HCl]0/[ZnCl2]0 = 5.0/2.0 mM). The polymerization of 1 was very slow and gave only low‐molecular‐weight polymers with a number‐average molecular weight (Mn) of about 2000 even at 100% monomer conversion. The structural analysis of the products showed occurrence of chain‐transfer reactions because of the urethane group of monomer 1. In contrast, the polymerization of vinyl ether 2 proceeded much faster than 1 and led to high‐molecular‐weight polymers with narrow molecular weight distributions (MWDs ≤ ∼1.2) in quantitative yield. The Mn's of the product polymers increased in direct proportion to monomer conversion and continued to increase linearly after sequential addition of a fresh monomer feed to the almost completely polymerized reaction mixture, whereas the MWDs of the polymers remained narrow. These results indicated the formation of living polymer from vinyl ether 2. The difference of living nature between monomers 1 and 2 was attributable to the difference of the electron‐withdrawing power of the carbamate substituents, namely, n‐butyl for 1 versus phenyl for 2, of the monomers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2960–2972, 2004

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To develop new phenylacetylene monomers more suitable for helix-sense-selective polymerization (HSSP) we reported previously and to improve the efficiency of the HSSP and membrane performance of the resulting polymers, novel phenylacetylenes having a flexible oligosiloxanyl group (SnBDHPA) together with the other related three series of monomers were synthesized and polymerized by using a chiral catalytic system and enantioselectivity in permeation of the membranes from the resulting chiral polymers were examined. SnBDHPA was the most suitable for the HSSP and the CD absorptions (G values) of poly-(SnBDHPA) were stronger and more stable than those of the corresponding polymers having rigid alkyl groups. The polymers could be fabricated to flexible self-supporting membranes by using solvent-casting method. In addition, enantioselectivity in permeation of one of poly(SnBDHPA) membranes was much higher than that of a poly(phenylacetylene) membrane having alkyl groups. This was because the polymers having oligosiloxane groups had high regularity of structures, i.e., chemical structures of the macromolecules such as one handedness and high order structures such as columnar contents in the membranes, and the membranes were flexible and had almost no defects. These good properties as optical resolution membrane materials were caused by flexibility, hydrophobicity, and bulkiness of the oligosiloxane chains. S3BDHPA having a trisiloxanyl group was found to be the best monomer for the HSSP and for obtaining good optical resolution membrane materials.