Functional monomers and polymers. XXXXVI. A copolymerization study of methacryloyl-type monomers containing nucleic acid bases in chloroform solution

Behavior of the free radical copolymerization of N-β-methacryloyloxyethyl derivatives of adenine with that of thymine was studied in chloroform solution, taking account of the specific base-base interaction of these monomers. Hydrogen bonding interaction between such monomers was observed by NMR spectroscopy. The acceleration of copolymerization was found to be greater either at lower monomer concentration or at lower polymerization temperature. When N-β-methacryloyloxyethylcarbazole was used as a comonomer, the rate of copolymerization showed a similar trend as in the case of usual free radical copolymerizations. From r₁ and r₂ values obtained, the copolymerization was found to be alternating, particularly in the case of copolymerization between monomers having complementary nucleic acid bases. The results suggest that the hydrogen bonding interaction between adenine and thymine plays a role in the propagation step.     

Functional monomers and polymers. CXXXII. Template polymerization of methacrylamide derivatives containing nucleic acid bases

Free-radical polymerizations of methacrylamide derivatives containing nucleic acid bases were studied in the presence of the polymethacrylamide having complementary nucleic acid bases as template polymers. The rate of the polymerization did not show remarkable difference in the presence or the absence of the template polymer. A stable polymer complex, however, was precipitated from the polymerization system, and was found to be different in a thermal analysis from the polymer complex which was obtained by mixing of the complementary polymers in solution. Free-radical copolymerizations in the presence of the template polymers also supported the template polymerization.     

Functional monomers and polymers. XIX. Copolymerization of vinyl monomers containing nucleic acid bases

Taking into account the specific base–base interaction existing between nucleic acid molecules, we studied the free-radical copolymerization of N-β-methacryloyloxyethyl derivative of uracil with that of adenine at 60°C in various solvents. N-β-Methacryloyloxyethyltheophylline as well as methyl methacrylate were used also as comonomers. From the data on the rates in different comonomer feed ratios and the r₁ and r₂ values obtained, copolymerizability was discussed in some detail. The results suggest that the interaction between uracil and adenine bases plays a role in the copolymerization behavior.     

Functional monomers and polymers. XXXXVII. Complex formation of stereoregular methacryloyl-type polymers containing nucleic acid bases

The complex formation between a poly(N-β-methacryloyloxyethyl) derivative of adenine with one of thymine or uracil was studied in dimethyl sulfoxide and ethylene glycol mixture by ultraviolet (UV) spectroscopy. For the polymer pairs containing complementary nucleic acid bases both hypochromicity and hyperchromicity were found. Stereoregularity of the polymers, as well as the conditions for measurement of, for example, solvent, temperature, and time, affected the complex formation. Both inter- and intramolecular interaction of polymers in solution were discussed in some detail.     

Functional Monomers and Polymers Containing Nucleic Acid Bases: Experiments on Template Polymerization

In order to see how the specific base-base interactions observed between complementary nucleic acid bases can be realized for free-radical polymerization systems, the template polymerization of methacrylate type monomers containing nucleic acid bases in the presence of template polymers containing complementary bases was studied. Stereoregular polymers were chosen as the template polymers. The radical copolymerization of the monomers containing complementary nucleic acid bases was also studied in different solvents.     

Functional monomers and polymers. LXXI. Conformation and interaction studies of poly-L-lysine derivatives with pendant nucleic acid bases

Copolymers of L -lysine and L -lysine derivatives which contained nucleic acid bases substituted on the N^ε position were synthesized by grafting nucleic acid derivatives onto poly-L -lysine. The conformation and interaction of these copolymers in solution were studied by using spectroscopic measurements. They existed in helical conformation at neutral pH values, and the polymer complex formation among them was examined by ultraviolet (UV) measurements in organic solvents. A decrease in the nucleic acid base content of the copolymers resulted in a decrease in helical structures and also in interactions with the polymer-containing complementary bases.     

Functional monomers and polymers. LXIII. A study on the polymer–polymer interaction between nucleic acid base-substituted poly-L-lysines

A study of polymer-polymer interaction was made on several poly-L -lysines that contained pendant nucleic acid bases substituted on the N′ position. Conformation and interaction of these polypeptides were studied in solution by spectroscopic measurement. The results obtained suggest that the high-molecular-weight polymers form polymer complexes in a helical conformation by specific adenine-thymine base pairing. On the other hand, no interaction could be observed for the low-molecular-weight polymers, which existed in a random coil structure.     

Functional monomers and polymers. CXXXI.. Synthesis and interaction studies on polyacrylamide and polymethacrylamide derivatives containing nucleic acid bases

Acrylamide and methacrylamide derivatives of nucleic acid bases were prepared from the corresponding aminoethyl derivatives. Free-radical polymerization of these monomers in water or in organic solvents gave their polymers. From the studies of the polymer complex formation by UV spectroscopy, it was found that extremely stable polymer complexes were formed between complementary polymers containing nucleic acid bases.     

Synthesis of polyesters containing nucleic acid base derivatives as pending side chains

Preparations of four diol monomers containing nucleic acid bases and the corresponding model polymers of polynucleotides with linear polyester backbone and nucleic acid base derivative as pending side chains are described. N-(1′,3′-Dihydroxy-2′-methyl-2′-propyl)-2-(thymin-l-yl)propionamide ( Ia , HMPTPA), N-(1′,3′-dihydroxy-2-methyl-2′-propyl)-2-(uracil-l-yl)propionamide ( Ib , HMPUPA), and their isomers, N-(β,β′-dihydroxyethyl)-2-(thynin-1-yl)propionamide ( IIa , HETPA) and N-(β,β′-dihydroxyethyl)-2-(uracil-1-yl)propionamide ( IIb , HEUPA) were synthesized through the selective N-acylation of 2-methyl-2-amino-1,3-propanediol and diethanolamine with 2-(thymin-1-yl)propionic acid (TPA) and 2-(uracil-1-yl)propionic acid (UPA), respectively, by the active amide-benzotriazole method. Diol monomers I and II were polycondenzed with active amide of benzotriazole such as 1,1′-(isophthaloyl)bisbenzotriazole (IPBBT) in the presence of triethylamine and in DMF at 60°C, giving polyesters containing thymine and uracil derivatives as the side group. Prior to polymer synthesis, an O-acylation of Ia using the active monoamide l-benzoylbenzotriazole was carried out as a model compound study.     

Synthesis of diols containing nucleic acid bases and their polyesters

Preparation of four diols containing nucleic acid bases derived from 3-(thymin-1-yl)propanoic acid (3-TPA) and 3-(uracil-1-yl)propanoic acid (3-UPA), and the corresponding model polymers of polynucleotides with linear polyester backbone and nucleic acid base derivative as pendant side chains are described. N-(1′,3′-Dihydroxy-2′-methyl-2′-propyl)-3-(thymin-1-yl)propionamide ( VIa , 3-HMPTPA), N-(1′3′-dihydroxy-2′-methyl-2′-propyl)-3-(uracyl-1-yl)propionamide ( VIb , 3-HMPUPA) and their isomers, N(β,β-dihydroxyethyl)-3-(thymin-1-yl)propionamide ( VIIa , 3-HETPA), and N-(β,β-dihydroxyethyl)-3-(uracil-1-yl)propionamide ( VIIb , 3-HEUPA) were synthesized through the selective N-acylation of 2-methyl-2-amino-1,3-propanediol and diethanolamine with 3-TPA and 3-UPA, respectively, by the active ester-N-hydroxyl-1,4-epoxy-5-cyclohexene-2,3-dicarboximide (HOEC) method. The resulting diols were polycondensed with active diamide of benzotriazole (HBT) such as 1,1′-(isophthaloyl)bis-benzotriazole (IPBBT), giving polyesters containing thymine and uracil derivatives as the side group, by the selective O-acrylation of active amide-benzotriazole method.     

Water soluble nucleic acid analogs: Preparation and properties

In order to prepare water soluble natural and synthetic polymers, which contain nucleic acid base units as the functional side groups, a different sort of polymers, such as poly(ethyleneimine), poly(amino acids) and so on were used as the base materials. The properties of the polymers derived, in particular the specific interaction between nucleic acid base containing complementary polymers was studied in detail. Introduction of the base units onto hyaluronic acid was also carried out. Applicabilities of these polymers obtained, for example as the controlled release system by using reversible photodimerization reaction of thymine bases were also shown.     

Functional monomers and polymers. XCIV. Photochemical reactions on the synthetic polymers containing thymine bases in the presence of adenine derivatives

Photodimerization reactions of polyacrylate and polymethacrylate derivatives and the dimer model compound containing thymine bases were studied in the presence of adenine derivatives in dimethyl sulfoxide; N,N-dimethylformamide; and dimethyl sulfoxide–ethylene glycol solutions. The photodimerization of thymine bases both in the polymers and in the dimer model compound was found to be quenched by the addition of adenine derivatives. Base-base interaction in the ground state was also studied by ultraviolet (UV) spectroscopy in the three solvents. The quenching of the photodimerizationof thymine bases in the presence of adenine derivatives was discussed in terms of the specific interaction between adenine and thymine bases both in ground and excited states.     

Polymerization of surface-active monomers. II. Polymerization of quarternary alkyl salts of dimethylaminoethyl methacrylate with a different alkyl chain length

The cationic monomers (C_NBr), obtained by quarternization of dimethylaminoethyl methacrylate with n-alkyl bromide containing varying carbon number (N = 4, 8, 12, 14, and 16) were polymerized with radical initiators in water and various organic solvents. The degree of polymerization of the resulting polymers was determined by GPC measurements on poly(methyl methacrylate) samples derived from them. The rate of polymerization of the micelle-forming monomers (N = 8, 12, 14, and 16) in water increases with increasing a chain length of alkyl group, whereas it is little dependent on N in isotropic solution in dimethylformamide. The data on the degree of polymerization for the polymers of C₄Br, C₈Br, and C₁₂Br show that the polymerization of C₁₂Br with azo initiators in water and benzene gives polymers with a very high degree of polymerization. The results obtained here suggest that highly developed or relatively rigid, aggregated structures of monomers in solution are responsible for the formation of the polymers with a very high degree of polymerization, in addition to an enhanced rate of polymerization. Also considered are the relation of the molecular weight of poly(C₁₂Br) to the viscosity data in chloroform and methanol.     

1,3-Dipolar cycloaddition reaction of aryl nitrile oxides with alkenes using imidazole and pyridine containing reusable polymeric base catalysts

Cross-linked poly-1-(4-vinylbenzyl)imidazole and cross-linked poly-4-vinylpyridine have been prepared from respective vinyl monomers using different quantities of divinylbenzene as a cross-linker by radical polymerization. The polymeric bases were characterized by FT-IR, TGA, field emission-scanning electron microscopy (FE-SEM), and Brunauer-Emmett-Teller (BET) surface area analysis. Their swelling behavior was also studied. They were used as base catalysts for 1,3-dipolar cycloaddition reaction of aryl nitrile oxides, generated in situ from N-hydroxyimidoyl chloride, with N-phenylmaleimide and ethyl acrylate, to obtain 3-arylisoxazolines. Both the bases gave excellent results. These polymers were reusable, safe to use, and provided good alternative for organic nonreusable bases like pyridine and triethylamine which are hazardous.     

Functional monomers and polymers. CXXI. Methylation and interaction studies on adenine containing polymethacrylate derivatives

Studies of the methylation of polymethacrylate derivatives with adenine bases were made in comparison to those with uracil bases. The polymethacrylate derivatives with adenine bases were methylated by using methyl iodide in dimethyl sulfoxide solution to produce polymers that contained N¹-methyladenine and N¹, N⁶-dimethyladenine units. The products were identified by spectroscopic data and by preparing their model compounds. The methylated polymers obtained were further applied in a study of polymer complex formation with uracil-base polymers.     

Oxoaminium salts as initiators for cationic polymerization of vinyl monomers

Oxoaminium salt ( 1 ), derived from 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO, 2 ) by one-electron oxidation, could be an initiator for cationic polymerization of vinyl monomers such as isobutyl vinyl ether (IBVE), 2,3-dihydrofuran, p-methoxystyrene, N-vinyl pyrrolidone, etc., to give the corresponding polymers, when 1 had a low nucleophilic counter anion. Formation of the adducts of 1 and IBVE as well as ¹H-NMR and IR data suggested the formation of polymers containing N? O? C structure as the polymer head group. In the polymerization of IBVE, the effects of solvent and concentration of 1 were little observed, however the polymerization rate was dependent on temperature. Furthermore, the thermal reaction of the polymers obtained, which were regarded as prepolymers for block copolymerization and polymeric initiators for radical polymerization, was studied. For example, poly(2-benzylidene-1,3-dioxane) obtained by the polymerization of 2-benzylidene-1,3-dioxane with oxoaminium hexafluoroantimonate ( 1, X = SbF₆) was employed as an initiator for radical polymerization of MMA to give its block copolymer with PMMA. © 1993 John Wiley & Sons, Inc.     

Living cationic polymerization of vinyl ethers in the presence of a strong base: Poisonous or helpful?

A quite small dose of a poisonous species was found to induce living cationic polymerization of isobutyl vinyl ether (IBVE) in toluene at 0 °C. In the presence of a small amount of N,N‐dimethylacetamide, living cationic polymerization of IBVE was achieved using SnCl₄, producing a low polydispersity polymer (weight–average molecular weight/number–average molecular weight (M_w/M_n) ≤ 1.1), whereas the polymerization was terminated at its higher concentration. In addition, amine derivatives (common terminators) as stronger bases allow living polymerization when a catalytic quantity was used. On the other hand, EtAlCl₂ produced polymers with comparatively broad MWDs (M_w/M_n ～ 2), although the polymerization was slightly retarded. The systems with a strong base required much less quantity of bases than weak base systems such as ethers or esters for living polymerization. The strong base system exhibited Lewis acid preference: living polymerization proceeded only with SnCl₄, TiCl₄, or ZnCl₂, whereas a range of Lewis acids are effective for achieving living polymerization in the conventional weak base system such as an ester and an ether. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6746–6753, 2008     

On the polymerization reactivity of fluorinated vinyl monomers

The polymerization reactivities of α,β,β‐trifluorovinyl compounds (CF₂=CF—R) and α‐trifluoromethylvinyl compounds (CH₂=C(CF₃)—R) are discussed since these monomers have scarcely been investigated and hardly yielded corresponding homopolymers, although tetrafluoroethylene and chlorotrifluoroethylene have been studied under radical polymerization conditions. In the case of α,β,β‐trifluorostyrene, a homopolymer is obtained in low yields by anionic polymerization and it is concluded that the reaction takes place without any side reactions once the reaction has started, since simple addition polymerization is observed and the molecular weight distribution is very narrow. Anionic polymerization of hexafluorobuta‐1,3‐diene is successfully achieved by the addition reaction of living end to the 2‐carbon of hexafluorobuta‐1,3‐diene followed by isomerization to produce excellently high thermostable polymers. ω‐Trifluorovinyloxyfluoroalkyl alcohol produces a polyether via a polyaddition reaction under anionic conditions. The homopolymers of α‐trifluoromethylacrylates are quantitatively obtained under anionic polymerization conditions. α‐Trifluoromethylstyrene derivatives are likely to polymerize under radical conditions, but are not well‐studied. The radical polyaddition reaction of perfluoroisopropenyl esters in 1,4‐dioxane, diethyl ether or 1,2‐dimethoxyethane yields the polymers possessing the solvent moiety in the polymer main chain, respectively. It is clearly demonstrated that each fluorinated vinyl monomer discussed in this article demands its own reaction conditions. Therefore, more experimental data on the polymerization of these individual monomers is needed, including research on developing the reactions discovered in the organofluorine chemistry field to the preparation of polymers.     

Vinyl monomers bearing chromophore moieties and their polymers. III. Synthesis and photochemical behavior of acrylic monomers having phenothiazine moieties and their polymers

Four acrylic monomers bearing phenothiazine moieties, i.e., N-acrylyl-phenothiazine (APT), N-acrylyl-2-chlorophenothiazine (ACPT), N-acrylyl-2-acetylphenothiazine (AAPT), and 10-acrylyl-1-azaphenothiazine (AAzPT) were synthesized by dehydrohalogenation of the corresponding N-(β-chloropropionyl)-substituted phenothiazine derivatives with 1,8-diazabicyclo[5.4.0]undec-5-ene (DBU). These monomers could easily be polymerized by initiation with AIBN. The emission fluorescence spectra of the monomers and their polymers were recorded, which showed that the polymers displayed much stronger fluorescence than their corresponding monomers at the same chromophore concentrations. This phenomenon, as termed as “structural self-quenching effect,” was commonly observed for acrylic monomers bearing chromophore moieties and ascribed to the coexistence of the electron-donating chromophore and the electron-accepting double bond in the same molecule. Because of the formation of exciplex, the monomer APT, as well as ACPT, AAPT, AAzPT, and their polymers, could initiate the photopolymerization of AN. The charge transfer phenomenon between P(APT), P(ACPT), and C₆₀ was also explored. © 1996 John Wiley & Sons, Inc.     

Study of radiation-induced polymerization of vinyl monomers adsorbed on inorganic substances. V. Effects of p-benzoquinone and dose rate on methyl methacrylate–silica gel system

In order to elucidate the mechanism of radiation-induced polymerization of methyl methacrylate adsorbed on silica gel, the effects of p-benzoquinone addition and dose rate were studied in detail. Most of the polymerization is inhibited by p-benzoquinone at levels above 10^-2 mole/l. The GPC spectra of both graft polymers and homopolymers show two peaks. The high molecular weight material appears to have been formed by polymerization by a radical mechanism, because these peaks decrease as p-benzoquinone concentration increases; on the other hand, their low molecular weight polymers seem to be products of an ionic polymerization mechanism because those peaks are almost not affected by p-benzoquinone. The four GPC peaks differ in dose rate dependences of their polymerization rate. The dose-rate exponents of polymerization rate were obtained for the four GPC peaks. The behavior of the low molecular weight peaks of graft polymers and homopolymers were quite different, suggesting that the polymers differ considerably in formation mechanism.