This article focuses on the synthesis of sequential condensation polymers by direct polycondensation through the control of the reactivities of functional groups. Various synthetic approaches to sequential polymers, such as the syntheses of sequential polymers from symmetric (XaaX) and nonsymmetric monomers (YcdY), from two nonsymmetric monomers (XabX) and (YcdY), and from three nonsymmetric monomers (XabX), (YcdY), and (ZefZ), are presented. Methodologies and requirements are also described.

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Various second catalyst components (organometallic cocatalysts) were examined to develop novel catalyst systems for the living polymerization of substituted acetylenes. It had been known that the MoOCl₄-n-Bu4Sn-EtOH catalyst effects living polymerization. In the present study we found that novel catalyst systems such as MoOCl₄-Et₃Al-EtOH, MoOCl₄-Et2Zn-EtOH, and MoOCl₄-n-BuLi polymerize [o- (trifluoromethyl) phenyl] acetylene (o-CF3PA) in a living fashion. Anisole was a favorable solvent and catalyst compositions of MoOCl₄: Et3Al: EtOH=1: 1: 4, MoOCl₄: Et₂Zn: EtOH=1: 1: 3, and MoOCl₄: n-BuLi=1: 1 were preferable. Interestingly, the MoOCl₄-n-BuLi system does not require EtOH as a third catalyst component. Living nature of the present systems was confirmed by multistage polymerization. The polydispersity ratios of the poly (o-CF3PA) 8 obtained in the present study were as small as 1.02-1.03, whereas the initiator efficiencies varied in a wide range of 2-40% depending on the catalyst systems. A block copolymer can be successfully prepared from o-CF₃PA and o-Me₃SiPA.

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Methodologies for precision polymerization based on biotechnology are reviewed. Gene technology was used for incoporation of polyproline residues of various lengths into the carboxyl terminal of enzymes. The mutant enzymes were hydrophobic and had functions which were different from those of wild-type enzymes. Expanded gene technology for incorporation of nonnatural amino acids into proteins is also described. Several synthetic methods of misacylated tRNA for the purpose are reported. Molecular evolution engineering, in vitro selection, is reviewed which utilizes an enzymatic polymerization method, polymerase chain reaction (PCR). The future progress using nonnatural nucleic acids is discussed.

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Achiral aromatic isocyanates were polymerized with various optically active anionic initiators in tetrahydrofuran (THF) at -98°C. Obtained polymers showed a much larger specific rotation than that expected from a chiral initiator residue introduced at the initial chain end (α-end). This result indicates that this optical activity is mainly due to a prevailing helical structure of a polymer caused by an optically active initiator residue attached to the α-end. Although it has been suggested that poly (aromatic isocyanate) s have a random coil conformation in solution, it became clear that the polymers can maintain a helical structure, even in solution, as well as poly (alkyl isocyanate) s can. In order to get information on the helical structure of poly (aromatic isocyanate) s, oligomers of aromatic isocyanates with a chiral residue at the α-end were synthesized and fractionated in terms of degree of polymerization using high-performance liquid chromatography (HPLC) or supercritical fluid chromatography (SFC) and their specific rotation was estimated. The chiroptical study of the obtained optically active oligomers indicated that in poly (aromatic isocyanate) s, helix reversals occur more often than in poly (alkyl isocyanate) s and the average persistence length of the helical structure of a polymer chain depends on the electric property of the substituent introduced on a phenyl group. Furthermore, optically active aromatic isocyanates were synthesized and polymerized with an achiral anionic initiator to obtain optically active polymers. The obtained polymers had a prevailing helical structure and showed the ability to discriminate enantiomers in CDCl₃. This is the first example of chiral discrimination with polyisocyanate.

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Chitin and chitosan, a heterocopolymer of N-acetyl-β-D-glucosamine (GlcNAc) and D-glucosamine (GlcN), were investigated from the following standpoint: 1) the determination of degree of deacetylation (DDA), 2) the sequence reguladty, 3) the relationship between the bioactivities and DDA. DDA of a deacetylated chitin (DAC) or a partially N-acetylated chitosan (PAC) can be determined accurately by infrared spectroscopic method using a calibration line obtained by ratios of intensity of the 1560cm^-1 absorption band as a determination band to that of the 1070cm^-1 or 1030cm^-1 absorption band as an internal standard against DDA determined another method. The sequence regularity of GlcNAc and GlcN residues in DAC and PAC prepared under homogenoous or heterogeneous conditions was investigated by nitrous acid deamination and Bernoullian statistical analysis. These results indicate a random distribution of GlcNAc residues in the DAC and PAC. The relationship between bioactivities, antibacteria and polymorphonuclear cell activation, and DDA of DAC and PAC were also investigated. The bioactivities were strongly depemded on the DDA.

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Based on the reversible redox properties of π-conjugate polymers, polyanilines and polypyrroles were demonstrated to serve as catalysts in dehydrogenative oxidation reactions of benzylamines, 2-phenylglycine, and 2, 6-di-t-butylphenol under oxygen. The catalytic activity was controlled by protonic acid doping of polyanilines. In situ UV-Vis spectroscopy showed that protonic acid doping is essential in the reversible redox process of polyaniline. In π-conjugate polymertransition metal complexes, transition metals are considered to electronically interact with each other through a π-conjugate polymer chain. Polyaniline and transition metal such as copper (II) chloride or iron (III) chloride formed a complex, which was effective in the dehydrogenative oxidation of cinnamyl alcohol or mandelic acid. The high catalytic activity of the complex is considered to be partially due to the higher redox potential. In situ UV-Vis spectroscopy showed that transition metal participates in the formation of the reversible redox process of the polymer. Polyaniline was redox-coupled with low-valent transition metals such as Cu (I), Fe (II), Mn (II), V (II), and Sm (II), which reduced polyaniline. The complex was found to be oxidized by oxygen. A complex system consisting of palladium (II) acetate and polyanilines or polypyrroles permitted the catalytic Wacker oxidation, indicating that the π-conjugate polymers serve as a redox-active ligand.

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A nonmetallocene-type rare earth metal complex, [(SiMe₃) ₃C] ₂Yb, was found to proceed the isotactic polymerization of methyl methacrylate (MMA) to give a high molecular weight polymer with narrow molecular weight distribution. We can synthesize stereo-complexes of poly (MMA) by mixing the resulting isotactic polymer with the high molecular weight syndiotactic poly (MMA) synthesized with SmH (C₅Me₅) 2. Half-sandwich type rare earth metal complex, (C₅Me₅) La [CH (SiMe₃) ₂] ₂, proceeds the polymerization of styrene, alkyl isocyanates, acrylonitrile, and ethylene. Furthermore, rare earth metal complexes exhibiting one cyclopentadienyl group and one acetylene group or benzyl group also showed relatively large catalytic activity for the polymerization of ethylene. A novel triphenyl complex, (2, 6-alkoxy C₆H₃) ₃Sm, was also prepared but this complex showed very weak catalytic activity towards the polymerization of ethylene.

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This article describes the conceptualization and syntheses of a series of well-defined carbohydrate macromolecules having a determined number of sugar residues, based on architectural control by living polymerization and dendrimer stepwise production. Synthetic cascades using living Polymerizations of 2-oxazolines and sugar-substituted α-amino acid N-carboxyanhydrides (glycoNCAs) afforded a variety of artificial glycoconjugates, e. g., saccharide-bearing macromonomers, graft copolymers, block copolymers, and dendrimer-based star polymers (AB_n-type block copolymers between dendrimer and linear polymer). The star block copolymers with the inner dendrimer have been synthesized by living radial-growth polymerization (RGP) of glycoNCAs with poly (amido amine) dendrimer as a multi-functional macroinitiator. An architectural strategy to sophisticated carbohydrate macromolecules is introduced, including molecular design of intersugar space-controllable sugar balls (sugar-persubstituted dendrimers) by quantitative polymer reaction on the surface of dendrimers.

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Stereofegular poly (methyl methacrylate) s (PMMAs) having a functional group at their teminating chain-end were prepared by stereospecific living polymerization. The resulting end-functional PMMAs were fractiomted into uniform polymers by means of supercdtical fiuid chromatography (SFC). The uniform PMMAs thus obtained were effectively used as building blocks to construct stereoregular uniform polymer arcllitectures, such as stereoblock, star, and comb-like polymers. Stereoblock PMMA with uniform block lengths (uniform stereoblock PMMA) was prepafed by coupling feaction between isotactic (it-) and syndiotactic (st-) PMMAs having a hydroxyl end group, fbllowed by GPC or SFC separation. The resulting uniform sterooblock PMMA was found on the basis of GPC analysis to form intraand intermolecularly associated stereocomplexes in acetone. Uniform isotactic and syndiotactic three-arm star PMMAs were also prepared by the coupling reaction between PMMA-OHs and 1, 3, 5-benzenetricarbonyl trichloride. Stefeoreg-Ularity of the branches was found to affect the branching effect on the solution viscosity of the star polymers. Polymerizations of uniform st-and it-PMMA macromonomers were carried out with radical and anionic initiators. The products were separated by GPC or SFC into uniform oligo (macromonomer) s, whose solution viscosities clearly showed branching effect. Anionic copolymerization of the uniform macromonomers with DPs of prime numbers (25 and 31) gave the products consisting of copolymer homelogues each of which has a number of monomer units different from the others, and the products could be fractionated into each component by means of SFC. Quantitative analysis of the product distribution by SFC gave information on the reactivities of macromonomers and pfopagating mions.

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A series of aryl ether dendrimer porphyrin complexes were synthesized by a convergent approach. Iron porphyrin encapsulated within a large dendrimer framework reversibly bound dioxygen in the presence of 1-methylimidazole, where the resulting dioxygen adduct survived for more than 2 months even in the presence of water and (also) exhibited a high durability toward carbonylation under carbon monoxide with a half-life as long as 50h. As a cytochrome c mimic, we also synthesized a water-soluble dendrimer zinc porphyrin with a negative-charged exterior surface ((-O₂C) ₃₂L₄PZn), which, upon mixing with a positive-charged electron acceptor such as methylviologen, formed a spatially separated donor-acceptor supramolecular assembly. Upon irradiation with visible light, a long-range photoinduced electron transfer occurred through the dendrimer framework at a rate constant of 2.6×109s^-1.

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The cyclopolymerization capable of forming monomeric units without planes of symmetry provides one useful means for asymmetric polymerization. Three succharides: L-threitol, α-D-glucose, and D-mannitol, were used as a template for asymmetric induction in radical cyclocopolymerization. The bis (p-vinylbenzoate) monomers (1a-c) (M₁) derived from the templates were copolymerized with styrene (M₂). The resulting copolymers (2a-c) were canverted into poly [(methyl 4-vinylbenzoate) -co-styrene] s (3a-c). The polymers were optically active; a sourse of chirality was the isolated M₁ unit. The exciton chirality method was employed for determining the absolute configuration of the cyclic units. The template having R, R-configuration transmitted its chirality to the main chain in the intramolecular cyclization of the monomer to form an enantiomeric S, S-racemo cyclic unit. The template having S, S-configuration gave the R, R-racemo cyclic unit. The acyclic template, (2S, 4S) -2, 4-pentanediol, was more effective than the cyclic templates such as the D-mannitol and L-threitol. The (2S, 4S) -2, 4-pentanediyl template approximately doubled in effect for the asymmetric induction by comparison with the (S) -1, 3-butanediyl one. The difference in the circular dichroism (CD) spectrum between the monomers from these templates was estimated by calculating the most stable rotational conformation and its energy level. The source of the optical activity in the cyclocopolymerizations was estimated by means of molecular mechanics and semiempirical molecular orbital calculation. The copolymerization of bis (methacryloyloxy) monomer (4a) (M₁) from L-threitol with styrene (M₂) induced the new chirality due to the isolated M₁ unit in the main chain as well. In contrast to the case of the L-threitol template, the copolymerization of bis (methacryloyloxy) monomer (4b) from D-mannitol indicated that the new chirality should be induced by the M₁ diad unit rather than the isolated unit.

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Synthesis of polysilabutane-block-poly (vinyl alcohol) amphiphilic block copolymer was investigated. Poly (1, 1-dimethylsilabutane) having dimethyl acetal group at the polymer end was synthesized by anionic ring-opening polymerization of 1, 1-dimethylsilacyclobutane in tetrahydrofuran (THF) -hexane-48°C, using 3-lithiobenzaldehyde dimethy acetal as an initiator. The dimethyl acetal group at the polymer end was converted into the formyl group by hydrolysis. Poly (1, 1-dimethylsilabutane) -block-poly (t-butyldimethylsilyl vinyl ether) was prepared by aldol group transfer polymerization (Aldol GTP) of t-butyldimethylsilyl vinyl ether using poly (1, 1-dimethylsilabutane) as a macro initiator. On hydrolysis of silyl ether groups of the polymer, polysilabutane-block-poly (vinyl alcohol) was obtained.

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Six cyclic pseudoureas having functional substituents were newly prepared, and their ring-opening isomerization polymerization initiated with methyl trifluoromethanesulfonate and double isomerization polymerization (DIP) initiated and catalyzed by methyl iodide were investigated. The monomers have a common base-structure of 2- (4-substituted piperadin-1-yl) -2-oxazoline (1b-e) or 2- (4-substituted piperidin-1-yl) -2-oxazoline (1f, g). The substituent on the imino ring strongly influenced the polymerization behavior of the monomers in DIP because of their neighboring group participation with the propagating alkyl halide end. The introduction of an aliphatic amide group enhanced the stability of the propagating end, particularly when the substituent was valeroyl (1c), while degradative chain transfer was induced when the substituent was ethoxycarbonyl (1e). The introduction of an ester (1f) or hydroxyl (1g) group caused significant chain transfer in both modes of polymerization.

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In order to clarify the differences of polymerizability among 1, 2: 5, 6-dianhydrohexitols, characteristics of the polymerizations of 1, 2: 5, 6-dianhydro-3, 4-di-O-methyl-D-mannitol (1), -L-iditol (2), and-D-glucitol (3) with potassium tert-butoxide (t-BuOK) were compared. The apparent rate constant of polymerization decreased in the order of 1>3>2. The polymerizations of 2 and 3 showed that chain transfer reactions occurred concurrently. End-functionalization in the polymerization of 1 proceeded in a high efficiency over 95% to yield macromonomers having a styryl group or oxetanyl group at a terminal. The result indicated that the polymerization of 1 proceeded in a living manner. The initiator efficiency in the polymerization of 1 was low (0.55) owing to the poor solubility of t-BuOK. 18-Crown-6 ether (18C6) increased the solubility of t-BuOK by forming a complex. The polymerization of 1 in the presence of 18C6 yielded the polymer with a number-average degree of polymerization (DPn) corresponding to the feed molar ratio of the monomer to the initiator ([M] 0/ [I] 0).

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A variety of cyclobutane adducts of tetracyanoethylene (TCNE) and various vinyl ethers are prepared and their pseudo-living cationic ring-opening polymerization is studied. The cyclobutane adducts of TCNE and n-butyl vinyl ether or methyl vinyl ether underwent pseudo-living cationic ring-opening polymerization with ethyl vinyl ether-acetic acid adduct/ZnI₂ in nitromethane at ambient temperature, similar to the polymerization behavior of the cyclobutane adduct of TCNE and ethyl vinyl ether with the same catalyst as reported previously. In the polymerizations of the cyclobutane adducts of TCNE and vinyl ethers with functional side chains, the cyclobutane bearing the 2-methoxyethoxy group underwent pseudo-living polymerization with the same catalyst.

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Addition-fragmentation chain transfer of methyl 2- (benzylthiomethyl) acrylate was employed for quantitative introduction of 2-carbomethoxy-2-allyl group to the ω-end of polymer. Although the allyl group is feasible to addition of the polymer radical of styrene (St), the polymer radical from methyl methacrylate (MMA) exhibited quite low reactivity. When St was polymerized in the presence of the poly (MMA) bearing the allyl end group, the addition of the poly (St) radical and subsequent coupling of the resulting radical with the poly (St) radical yielded a block copolymer consisting of a poly (MMA) chain and two poly (St) chains without crosslinking. Ethylene bis [2- (benzylthiomethyl) acrylate] as a difunctional chain transfer agent yielded the poly (MMA) bearing two allyl groups to which the poly (St) radical readily added to form branching. The addition to the allylic end group and the subsequent coupling with the poly- (St) radical could lead to a six-armed polymer. The allylic end group was found to react quantitatively in the presence of an excess amount of St monomer relative to the end group, and the homopolymerization of St was not avoidable.

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Sixteen porphyrin rings were introduced to dendritic poly (L-lysine). The synthesis of lysine dendrimer was carried out starting with hexamethylenediamine and Boc-Lys (Boc) -OH. At the fourth generation, a lysine monomer containing a porphyrin ring, Boc-Lys (Por) -OH was coupled to introduce 16 porphyrin rings on the side chain of lysines. Further, the main chain was elongated to the sixth generation. The Boc-Lys (Por) -OH was also introduced at the third or fifth generation to allow different numbers of porphyrin rings to be stratified in the dendritic poly (L-lysine). These dendrimers were soluble in dimethyl formamide (DMF), dichloromethane (DCM), and tetrahydrofuran (THF). Circular dichroism (CD) spectra of the dendrimers gave no significant peaks in DMF. However, a strong split Cotton effect was observed increasingly in CD by the addition (>50%) of toluene. We presume that stratified porphyrins formed a chiral conformation in the dendrimer by a mixed solvent effect of DMF (good solvent for polypeptide) and toluene (good solvent for porphyrin).

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The polymerizabilities of azine compounds (RCH=N-N=CHR) with various types of anionic initiators were investigated. Only oligomers were obtained by the polymerizations of alkyl azines (R=CH₃, C₂H₅, n-C3H7), although monomers were quantitatively consumed. This is because a chain transfer reaction took place in which the active chain end extracted the proton on the α-carbon of the C=N. Howevet, high molecular weight polymers were obtained by the polymerization by Grignard reagents. Spectroscopic analyses of the obtained polymers showed that the polymers consisted of trans-1, 4-units. Furthermore, we prepared trifluoroacetaldehyde azine (R=CF3, TFAcAz) to suppress the chain transfer reaction, and studied its polymerizability. In contrast to our expectation, only oligomers were obtained by the polymerizations of TFAcAz with BuLi, CH₃MgI, CH₃OK/18-crown-6, and 1, 8-diazabicyclo [5.4.0] undec-7-ene (DBU). However, TFAcAz was polymerized by triethylamine to form an insoluble polymer. The polymer was found to consist of 1, 2-units by several spectroscopies. In addition, the polymers obtained in this work were highly crystalline and thermodegradable.

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Polymerizations of 1-olefins with bulky substituents were conducted with an optically active metallocene catalyst system, i. e., (S) -ethylenebis (tetrahydroindenyl) zirconiumbis (O-acetyl- (R) -mandelate) -methylalumoxane (MAO). The polarimetric analysis of the resulting polymers in toluene solution revealed that some of the 1-olefins with α-branches like poly (3-methyl-1-pentene) and poly (3-methyl-1-butene) display optical rotation. However, poly (vinyl cyclohexane) having a similar α-branch did not show any optical rotation. This might be attributed to its higher solubility in toluene. It was also found that even the polymer of the non-branching 1-olefin shows optical rotation when it has a very long chain like 1-eicosene.

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Thermal polymerization of isolated bisphenol-A type macrocyclic oligocarbonates (dimer, trimer, tetramer, and pentamer) was carried out. Iu the cases of dimer and trimer, complete conversion to the corresponding linear polycarbonate was obtained at 300°C, in 20 and 40min, respectively. However, a small part of the tetramer still remained even after heating at 300°C for 40min. Although the pentamer exhibited much lower reactivity than 2-4 cyclic oligomers, its conversion was drastically improved by the presence of the dimer. The low reactivity of pentamer may be due to slow ionization of the bigger ring. The polymers obtained from trimer and tetramer had higher molecular weights (Mw>800000) than those obtained from dimer and pentamer.

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Inclusion compounds of cholamide with poly (ethylene glycol) s were prepared. X-Ray crystallographc study revealed that they had bilayer structures with molecular channels. The polymeric guest was incorported in the channel of the host lattice.

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