Synthesis and controlled polymerization of p-(1-methylcyclohexyloxy)styrene and quick-response deblocking ability of the obtained polymer

p-(1-Methylcyclohexyloxy)styrene (PC6ST) was synthesized by acid catalyzed addition reaction of p-bromophenol with 1-methylcyclohexene, followed by Grignard coupling with vinyl bromide catalyzed by NiCl₂(dppp). Radical polymerization of PC6ST in the presence or absence of TEMPO afforded poly(PC6ST) with narrow molecular weight distribution without the elimination of the protective group. The obtained poly(PC6ST) showed a higher deprotection ability in response to external stimulation such as an acid compared with poly(p-tert-butoxystyrene).     

Polymerization of methyl methacrylate with nickelocene‐methylaluminoxane catalyst

The polymerization of methyl methacrylate (MMA) catalyzed with cyclopentadienylnickel‐methylaluminoxane (Cp₂Ni‐MAO) was investigated. Polymerization readily proceeds with this catalyst, and the resulting polymer is rich in syndiotactic content. The effects of the MAO/Ni system on the polymerization activity of MMA were observed, and it was found that only small amounts of MAO are required to reach high polymerization activity.     

Cyclic carbonates,novel expandable monomers on polymerization

A variety of cyclic carbonates was shown to undergo volume expansion on polymerization. The degree of volume expansion, which was measured by the density gradient tube method, was ranging from 1.1% to 7.7%. The volume expansion was examined by assuming a change in molecular interaction such as dipole moment between monomer and polymer states.     

Transformation of the cationic growing center of poly(tetrahydrofuran) into an anionic one by bis(pentamethylcyclopentadienyl)samarium

Transformation of the cationic growing center of living poly(tetrahydrofuran) [poly(THF)] into an anionic one was achieved in high efficiency (62%) by the end-capping of living poly(THF) with potassium iodide followed by the reduction with bis(pentamethylcyclopentadienyl)samarium (Cp*₂Sm), whereas the direct reduction with Cp*₂Sm without the end-capping resulted in the formation of poly(THF) with pentamethylcyclopentadienyl group at the terminal. The increase in the molecular weight of poly(THF) after the reduction was observed, which indicates the presence of the dimerization of poly(THF) during the reduction. The polymerization of a variety of electrophilic monomers including δ-valerolactone, 2-oxo-1,3-dioxane, and alkyl methacrylates with the macroanion provided good yields of the corresponding block copolymers consisting of both cationically and anionically polymerizable monomers. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2209–2214, 1998     

Polymers with electron-deficient olefin moieties by oxidation of precursors containing “push–pull” olefin (β-alkylmercaptoenoate) moieties in the main chain

Oxidation of a polymer (1) having β-alkylmercaptoenoate moieties in the main chain by m-chloroperbenzoic acid (MCPBA) is described. Oxidation of 1 proceeded selectively to give polymers having vinyl sulfoxide or vinyl sulfone moieties in the main chain by using an appropriate amount of MCPBA. In the case of 1.1 equiv of MCPBA (relative to the sulfur atom), a polymer (4) having vinyl sulfoxide moieties selectively in the main chain was obtained in quantitative yield without side reactions. Likewise, a polymer (5) having vinyl sulfone moieties was obtained in quantitative yield by using 2.6 equiv of MCPBA. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2589–2592, 1998     

Copolymerization of cyclic ketene N,O-acetals with phenylisothiocyanate via zwitterionic intermediates

The reaction of 3-methyl-2-methylene-1,3-oxazolidine ( 1a ) and phenylisothiocyanate (PhNCS) gives 3-methyl-2-(phenylthiocarbamoyl)methylene-1,3-oxazolidine ( 3 ) whereas that of 2-isopropylidene-3-methyl-1,3-oxazolidine ( 1b ) and PhNCS gives 1:1 alternating copolymers. It is assumed that the reaction of 1b and PhNCS forms a zwitterionic intermediate ( 2b ), followed by the successive combination of 2b to give 1:1 alternating copolymers 4 and/or 5 . Consequently, it was demonstrated that the copolymerization of 1b and PhNCS proceeds via a zwitterionic mechanism with complete ring-opening to afford the 1:1 alternating copolymer 5 .     

Cationic polymerization behavior of seven-membered cyclic sulfite

Cationic ring-opening polymerization behavior of a seven-membered cyclic sulfite ( 1 ) was examined. 1 was prepared by the reaction of 1,4-butanediol with SOCl₂ in 58% yield. The cationic polymerization of 1 was carried out at 0, 25, 60, or 100°C with trifluoromethanesulfonic acid (TfOH), methyl trifluoromethanesulfonate (TfOMe), BF₃ · OEt₂, SnCl₄, methyl p-toluenesulfonate (TsOMe), or MeI as an initiator in bulk under a nitrogen atmosphere to afford the polymer with M̄_n 1000–10,400. The order of activities of the initiators for 1 was as follows, TfOH ≅ TfOMe > SnCl₄ > BF₃ · OEt₂ > TsOMe ≅ MeI. The polymerization of 1 with TfOMe afforded a poly(sulfite) below 25°C, but afforded a polymer containing an ether unit at 60°C, which was formed by a desulfoxylation. The higher the activity of the initiator was, the more easily the desulfoxylation occurred. We expected volume expansion on polymerization because cyclic sulfites have large dipole moment values, but it turned out that 1 showed 4.34% shrinkage on polymerization. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3673–3682, 1997     

Three-component coupling polymerization of bisallene,aryl dihalides,and nucleophiles via π-allylpalladium complex. II. Effect of nucleophiles on polymerization

A novel palladium-catalyzed three-component polycondensation of 1,2,10,11-dodecatetraene, 4,4′-diiodobiphenyl, and nucleophiles was carried out using various carbanions and amines as a nucleophilic part. The polymerization with various sodium diethyl malonates produced polymers in high yields. Particularly, no exo-double bond was detected in the polymers prepared from sodium diethyl malonates bearing substituents directly on the carbanion center. The ratios of E- and Z- isomeric units in the polymers were dependent on the structure of the nucleophiles used. Other carbanions with appropriate electron-withdrawing groups such as sulphones and ketones can be also used as a nucleophile for the present polycondensation. Within heteronucleophiles examined, cyclic amines were suitable to produce polymers in high yields. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1211–1218, 1997