Stepwise assembly of isotactic poly(methyl methacrylate) and syndiotactic poly(methacrylic acid) from acetonitrile and mixed acetonitrile/water solutions, respectively, onto a gold substrate was studied. Quantitative quartz crystal microbalance analysis of the molar ratio (monomer unit) between assembled polymers suggested stepwise stereocomplex formation. The assembled amount and the assembly ratio between PMAA and PMAA were dependent on the acetonitrile content of the poly(methacrylic acid) solution. Infrared spectra of the assembly and cast films of each polymer also showed stereocomplex formation in the assembly. Atomic force microscopic observation showed the assembled polymer to have a molecularly smooth surface. The solvent species used was an important factor in stereocomplex formation at the liquid−polymer film interface.

KEY WORDSN-Isopropylacrylamide / Acrylamide / Trialkylaluminum / Isotactic Polymer / Stereospecific Polymerization / Protected Monomer / Isomerization / Stereoregularity of vinyl polymers often affects significantly their properties and functions, and thus stereospecific polymerization has been important from the view points of both polymer chemistry and industry. In vinyl polymerization ionic and coordination processes have been considered favorable for the stereocontrol, in which proper selection of initiators, catalysts, additives and solvents may provide us with a handle for controlling stereoregularity in a wide variety. For example, we have shown that highly isotactic, syndiotactic, and heterotactic polymethacrylates could be prepared in toluene by using several anionic initiators; tert-butylmagnesium bromide (t-BuMgBr) for isotactic polymerization 1, 2 tert-butyllithium (t-BuLi) / trialkylaluminum (R 3 Al) for syndiotactic one 3, 4 and t-BuLi / bis(2,6-di-tert-butylphenoxy)methylaluminum [MeAl(ODBP) 2 ] for heterotactic one. [5][6][7][8][9][10][11][12][13] Polymers of acrylamide and its derivatives including N-isopropylacrylamide (NIPAm) are widely used in industry, agriculture and medicine due to their remarkable properties including good biocompatibility and low toxicity. 14, 15 Electron-withdrawing nature of amide groups might provide the monomers with potential reactivity favorable for anionic polymerization. However, the presence of acidic hydrogen in acrylamide itself and monosubstituted acrylamide inhibits the anionic vinyl polymerization.Thus radical polymerization has been so far the only means to obtain the corresponding polymers with few exceptions such as hydrogentransfer polymerization of α-(aminomethyl)acrylates 16 and N-acryloylurea derivatives with potassium tertbutoxide or 1,8-diazabicyclo[5.4.0]undec-7-ene. [17][18][19][20][21] As a consequence, stereospecific anioic polymerization of acrylamide derivatives have only been known for N, N-disubstituted ones. 22-28 Nakahama and his coworkers have reported successful stereospecific anionic polymerization of N, N-diethylacrylamide (DEA) in tetrahydrofuran (THF) by careful selection of Lewis-acid additives and counter cations. A syndiotactic poly(DEA) was prepared with alkyllithium initiator [1,1-bis(4 -trimethylsilylphenyl)-3-methylpentyllithium]/diethylzinc (Et 2 Zn), an isotactic one with t-BuMgBr/Et 2 Zn, and a heterotactic one with diphenylmethylpotassium (Ph 2 CHK)/Et 2 Zn. [29][30][31][32][33][34] In 1996, Okamoto and his coworkers 35 reported the anionic polymerization of N, N-diphenylacrylamide with t-BuMgBr in toluene at −78 • C, which gave an isotactic polymer with m diad of 80%. More recently, they also found that, in radical polymerizations of acrylamide and its derivatives, rare-earth metal trifluoromethanesulfonates (triflates) as Lewis-acid additives promoted stereospecific polymerization and, in particular, isotactic poly(NIPAm)s with m diad content of 92% were obtained with lutetium and yttrium triflates in methanol at −20 • ...

Various types of fluorine‐containing star‐shaped poly(vinyl ether)s were successfully synthesized by crosslinking reactions of living polymers based on living cationic polymerization. Star polymers with fluorinated arm chains were prepared by the reaction between a divinyl ether and living poly(vinyl ether)s with fluorine groups (C4F9, C6F13, and C8F17) at the side chain using cationogen/Et1.5AlCl1.5 in a fluorinated solvent (dichloropentafluoropropanes), giving star‐shaped fluorinated polymers in high yields with a relatively narrow molecular weight distribution. The concentration of living polymers for the crosslinking reaction and the molar feed ratio of a bifunctional vinyl ether to living polymers affected the yield and molecular weight of the star polymers. Star polymers with block arms were prepared by a linking reaction of living block copolymers of a fluorinated segment and a nonfluorinated segment. Heteroarm star‐shaped polymers containing two‐ or three‐arm species were synthesized using a mixture of different living polymer species for the reaction with a bifunctional vinyl ether. The obtained polymers underwent temperature‐induced solubility transitions in various organic solvents, and their concentrated solutions underwent sol–gel transitions, based on the solubility transition of a thermoresponsive fluorinated segment. Furthermore, a slight amount of fluorine groups were shown to be effective for physical gelation when those were located at the arm ends of a star polymer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

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