Reactivity of ester groups on insoluble polymer supports

A study was made of the comparative rates of reaction of active ester functional groups (p-nitrophenyl and 2,4-dinitrophenyl esters) situated on three types of insoluble support polymers and on small, soluble analogs of the polymer molecules. The supports consisted of a styrene—divinylbenzene bead-type polymer (2% DVB), a styrene—divinylbenzene popcorn polymer (0.2% DVB), and a popcorn polymer with 2,3-dimethylbutadiene and substituted styrene units in the chain. p-Nitrophenyl benzoate and 2,4-dinitrophenyl p-isopropylbenzoate were used as soluble analogs. Rates of aminolysis by small molecules (2-aminoethanol and n-tetradecylamine) in pyridine and of solvolysis in alcohols catalyzed by both small (N-methylimidazole) and large (polyvinylimidazole) molecules were determined. With the small amines, finely divided particles of popcorn and bead type styrene polymers reacted at about the same rate, which was approximately 1/5 the rate of reaction of the homogeneous analogs. With a high molecular weight reagent, polyvinylimidazole, the heterogeneous reactions were much slower and the popcorn polymer reacted faster than the bead polymer. In catalyzed solvolyses, the styrene popcorn derivative reacted faster in benzyl alcohol and slower in 1-hexanol than the dimethylbutadiene popcorn polymer derivatives.     

Study of photopolymer. XVII. Synthesis of novel photosensitive polymers with pendant photosensitive group and photosensitizer groups

Novel photosensitive polymers with pendant photosensitive group, such as cinnamic ester, and photosensitizer groups, such as N-carbamoyl-p-nitroaniline and N-carbamoly-4-nitro-1-naphthylamine, were synthesized from radical copolymerizations of (2-cinnamoyloxy)ethylmethacrylate with photosensitizer monomers, such as p-nitrophenylmethacrylamide and 4-nitro-1-na-phthylmethacrylamide, by using asobisisobutyronitrile (AIBN) in benzene and from the copolymerizations of (2-hydroxy)ethylmethacrylate or (2-hydroxy)ethylacrylate with photosensitizer monomers by using AIBN in DMF. This procedure was followed by condensation reactions of the copolymers with cinnamoyl chloride with pyridine as HCL acceptor in the same reaction flask. The photoreactivities of the polymers obtained were influenced by the concentration of photosensitive group and photosensitizer groups and their ratio in the polymer matrix. In addition, the photosensitivity of cinnamic ester groups attached to a soft polymer segment was higher than that of cinnamic ester group attached to a hard polymer segment when these polymers had the same pendant N-carbamoyl-p-nitroaniline group as photosensitizer. Furthermore, the spacer length between the polymer chain and photosensitizer group was important for increasing the photoreactivity of the photosensitive group in the polymers with pendant cinnamic ester and N-carbamoyl-p-nitroaniline groups.     

Asymmetric polymerization of aromatic isocyanates with optically active anionic initiators

The asymmetric anionic polymerization of o-, m-, and p-methylphenyl isocyanates, p-methoxyphenyl isocyanate, p-chlorophenyl isocyanate, 2,6- and 3,4-dimethylphenyl isocyanates, and 1-naphthyl isocyanate was carried out using chiral anionic initiators such as the lithium salts of (?) -menthol, (?) -(2-methoxymethyl) pyrrolidine, and (+) -1-(2-pyrrolidinylmethyl) pyrrolidine. Although o-methylphenyl isocyanate gave an insoluble polymer and 2,6-dimethylphenyl isocyanate afforded no polymer, the other monomers gave soluble polymers, which showed optical activity due to the prevailing helicity of the polymer chain induced by chiral initiator residues attached to the α-end of the polymer chain. The molecular mechanics conformational calculation for a tetramer of m-methylphenyl isocyanate supported the helical conformation of the main chain. The optical rotation of the polymers depended significantly on temperature. © 1994 John Wiley & Sons, Inc.     

Preparation of soluble microgel by the copolymerization of methylmethacrylate with p-divinylbenzene in the presence of tetrabromomethane

Various types of soluble crosslinked polymers obtained from the copolymerization of methylmethacrylate (MMA) and p-divinylbenzene (p-DVB) in the presence of a transfer agent (CBr₄) have been discussed in relation to the variation of the structure during the reaction time. When [p-DVB]/[MMA] = 1.49 × 10^?3 and [CBr₄]/[MMA] = 1.28 × 10^?4, only linear polymers (primary polymer; M _n = 1.0 × 10⁵) with pendant vinyl groups are formed intially. Considerable branched structure is attained in rather large polymers (M _n = 2.5 × 10⁵), but the number of pendant double bonds is not enough to reach the gelation. As the concentration of the transfer agent becomes high, the intermolecular crosslinking is depressed, and the formed polymers contain loops and short chains. At [p – DVB]/[MMA] = 7.43 × 10^?3 and [CBr₄]/[MMA] = 1.28 × 10^?3, the shape of polymer with the same M _n became compact gradually with increasing reaction time. These results are considered to be useful for the preparation of soluble crosslinked polymer with controlled structure.     

Photocrosslinkable polymers having p-phenylenediacrylate group in the side chain: Argon laser photoresist

Preparative methods and photosensitivity characteristics of polymers bearing the p-phenylene-diacrylate (PDA) group are described. Condensation of a copolymer of methyl methacrylate and glycidyl methacrylate with p-phenylenediacrylic acid monoester gave highly photosensitive polymers. An alternative method to introduce PDA group is the substitution of chloromethyl-styrene polymer with p-phenylenediacrylic acid monoester monoalkali salt. The latter method was found to be more favorable for preparing soluble photosensitive polymers. The polymers thus prepared showed high sensitivity to light of 488 nm from an Argon laser when sensitizers are used, and the photocrosslinking quantum efficiency was 0.44. Preliminary results on holographic recording with this polymer is also mentioned.     

Horseradish peroxidase-catalyzed polymerization of<Emphasis Type="Italic"> p</Emphasis>-hydroxycinnamic acid for synthesis of reactive microspheres

In this article, we report the experimental synthesis of reactive polymer microspheres of poly(p-hydroxycinnamic acid). Enzyme-catalyzed polymerization of poly(p-hydroxycinnamic acid) using horseradish peroxidase as a catalyst and hydrogen peroxide as an oxidant took place in a mixture solution of methanol and phosphate buffer solution; it was found that the fraction of methanol in the mixture solution strongly affected the yield of powdery polymer materials. The chemical structure of the polymers was characterized by ¹H-NMR and FT-IR spectroscopies, and the molecular weight was measured by gel permeation chromatography. The ¹H-NMR chart of the obtained polymer was almost the same as that of the monomer; FT-IR spectra indicated the existence of carboxyl groups. The weight-average molecular weight of the soluble part in tetrahydrofuran was found to be 1,451. Dispersion polymerization of p-hydroxycinnamic acid was carried out in a mixture solution of methanol and phosphate buffer solution by adding a dispersion stabilizer. Of the several such polymers tested, poly(vinyl alcohol) was found to be the most effective in producing reactive poly(p-hydroxycinnamic acid) microspheres.     

Effect of structure on properties of aromatic-aliphatic polybenzimidazoles. II

Polybenzimidazoles (PBI) with p-phenylene and/or cis-vinylene groups in the backbone were prepared from terephthalic acid (T), maleic acid (M), and 3,3′ diamino-benzidine tetrahydrochloride dihydrate (DAB) in poly(phosphoric acid) (PPA). Five polymer samples were prepared by varying the M:T molar ratios in the following order: 1:0, 1:1, 2:1, 1:2, and 1:4. The polymers were characterized by intrinsic viscosity, density, electronic fluorescence, and IR spectra. The effect of composition on the solubility of the polymers in various organic solvents was also investigated. The relative thermal stability of the polymers was evaluated by dynamic thermogravimetry in air and polybenzimidazoles (PBI) with cis-vinylene groups were found to be less stable.     

C3 cyclopolymerization. I. Is the cyclopolymerization of 1,3-bis(p-vinylphenyl)-propane by means of radical or anionic initiators possible?

Polymerization of 1,3-bis(p-vinylphenyl) propane (St-C₃-St) was investigated by using radical and anionic initiators. Radical polymerization yielded linear polymer with pendant styryl groups in pertinent conditions without gelation. Anionic polymerization with n-butyllithium and sodium naphthalene produced insoluble polymers that, according to infrared (IR) spectroscopy, had no cyclized units. On the other hand, phenylmagnesium bromide gave soluble polymer in HMPA-benzene mixed solvent. Zero-valent nickel catalyst also gave soluble polymer. The soluble polymers could be analyzed by several spectroscopies, and it was confirmed that those obtained by anionic and coordination polymerization had no [3.3]paracyclophane units in the main chain. From these results it was concluded that cationic propagation could be assumed if the polymer Of St-C₃-St contained [3.3]paracyclophane units in the main chain.     

Polymerization of substituted phenylacetylenes with a novel,water‐soluble Rh–vinyl complex in water

A novel, water‐soluble Rh complex, (nbd)Rh[PPh₂(m‐NaOSO₂C₆H₄)] [C(Ph)?CPh₂] ( 1 ) was synthesized by the reaction of [(nbd)RhCl]₂, Ph₂P(m‐NaOSO₂C₆H₄) and Ph₂C?C(Ph)Li, whose structure was determined by NMR and IR spectroscopies. The Rh catalyst 1 induced the polymerization of phenylacetylene (PA) in water to give two kinds of polymers; one was soluble in organic solvents such as tetrahydrofuran (THF) and CHCl₃, and the other was insoluble in common organic solvents. The polymerization of sodium p‐ethynylbenzoate (p‐NaOCO‐PA) homogeneously proceeded with 1 in water at 60 °C to give the polymer in high yield. Poly(p‐NaOCO‐PA) was treated with 1 N HCl and then reacted with (CH₃)₃SiCHN₂ to obtain poly(p‐MeOCO‐PA). The methyl‐esterified polymer was insoluble in THF and CHCl₃, which suggests that the formed poly(p‐MeOCO‐PA) has cis–cisoidal structure. The polymer obtained from the polymerization of [p‐CH₃(OCH₂CH₂)₂O₂CC₆H₄]C?CH with 1 in water was soluble in methanol, ethanol, and THF, and partly soluble in water. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2100–2105, 2004     

Polymerization of tert-alkylacetylenes by Mo- and W-based catalysts

Polymerization of three tert-alkylacetylenes (3,3-dimethyl-1-pentyne, 3,3-dimethyl-1-nonyne, 1-adamantylacetylene) by Mo- and W-based catalysts provided new polymers in virtually quantitative yields. In contrast, Ziegler catalysts did not polymerize these monomers. Every polymer had a form of white solid, and had alternating double bonds along the main chain. Though some of poly(3,3-dimethyl-1-pentyne)s contained a toluene-insoluble fraction, the polymer was totally soluble when proper polymerization conditions were chosen. The molecular weights of soluble fractions were as high as 3 × 10⁵. Poly(3,3-dimethyl-1-nonyne) was also partly insoluble in toluene, and the quantity of soluble fraction was less than that of poly(3,3-dimethyl-1-pentyne). The geometric structure of these two polymers could be controlled by the choice of suitable polymerization conditions. Poly(1-adamantylacetylene) was insoluble in any organic solvents. Copolymerization of 1-adamantylacetylene with suitable comonomers afforded soluble copolymers.     

Synthesis and properties of a poly(diphenylacetylene) containing carbazolyl groups

1-(p-N-Carbazolylphenyl)-2-phenylacetylene (p-CzDPA) was polymerized by TaCl₅–co-catalyst systems (cocatalysts: n-Bu₁Sn, Et₃SiH, and 9BBN) to produce acetone-insoluble polymers in about 60-70% yields. Poly(p-CzDPA) was a yellowish-orange solid, most part of which was soluble in toluene, chloroform, etc., and its weight-average molecular weights were around 4×10⁵. This polymer formed a tough film by solution casting, and was thermally very stable (the onset temperature of weight loss in TGA in air 470°C). The oxygen per-meability coefficient of the polymer at 25°C was lower than two barrers. The present polymer showed photoconductivity and redox activity. © 1995 John Wiley & Sons, Inc.     

Selective vinyl cationic polymerization of monomers with two cationically polymerizable groups. II. p-vinylphenyl glycidyl ether: An epoxy-functionalized styrene

p-Vinylphenyl glycidyl ether (VPGE), a styrene derivative with an epoxy pendant, was polymerized by various cationic initiators, and its selective vinyl polymerization was investigated at low temperatures below ?15°C. BF₃OEt₂ (a metal halide) and CF₃SO₃H (a strong protonic acid) polymerized both vinyl and epoxy groups of VPGE, and produced cross-linked insoluble polymers. The HI/I₂ initiating system and iodine, in contrast, polymerized its vinyl group in polar solvents (CH₂Cl₂ and nitroethane) highly selectively in the temperature range of ?15 to ?40°C to give soluble polymers with a polystyrene backbone and epoxy pendants; however, under these conditions, 10–15% of the epoxy groups of the polymers were consumed during the polymerization by the reaction with the growing species. The polymerization by HI/I₂ in CH₂CI₂ involved a long-lived propagating species, as indicated by a progressive increase in the molecular weight (M?_n) of the polymers with monomer conversion and their fairly narrow molecular weight distributions (M?_w/M?_n ～ 1.6). The differences between the polymerizations of VPGE and p-isopropenylphenyl glycidyl ether, an α-methylstyrene-type counterpart of VPGE, were also discussed with an emphasis on the effects of the α-methyl group in the latter monomer.     

Synthesis and polymerization of o-hexylaniline: Characterization of the corresponding polyaniline

In the field of research on soluble conducting polymers, the poly(o-alkylanilines) are very interesting because we can expect them to give more soluble polymers and new properties. Like poly(o-propylaniline) (POP), which is more soluble than polyaniline (PANi), poly(o-hexylaniline) (POH) appears to be more soluble in organic solvents than POP because of the longer alkyl groups in the 2-position. The higher solubility confers better processability on this new polymer, and because of this solubility, an NMR study in solution became possible.The nitration of hexylbenzene and the reduction of the resulting product to o-hexylaniline were performed according to the literature. The chemical polymerization was easy and it is possible to produce this polymer in large quantities.The polymerization carried out in anhydrous NH₄F, 2.35 HF medium and in 5 M perchloric acid gave a polymer with almost quantitative yield. The electrochemical behaviour of POH displayed faster electron transfers than PANi in organic solvents, depending on the acido-basicity level of the aqueous solutions. Unlike PANi, fractal growth was not observed.     

Polymerization of Si-containing acetylenes. XIV. Polymerization of diphenylacetylenes with bulky silyl groups and polymer properties

Polymerization and polymer properties of diphenylacetylenes with bulky silyl groups (SiMe₂–i-Pr, SiMe₂–t-Bu, SiMe₂Ph, SiEt₃) at para or meta position were studied under comparison with those of the SiMe₃ derivatives. The present monomers polymerized in good yields with TaCl₅-cocatalysts to form high molecular-weight polymers (M _w > 4 × 10⁵). The polymer yields of para-substituted monomers were similar to that of the SiMe₃ derivative, while those of meta substituted monomers were lower than that of m-SiMe₃ derivative. Most of the polymers were totally soluble in common solvents such as toluene and CHCl₃, although the polymers with p-SiMe₂–t-Bu and p-SiMe₂Ph groups were partly insoluble in all solvents. These polymers resembled SiMe₃-containing homologues in the UV-visible absorption and thermal stability. The oxygen permeability coefficients of these polymers were in the range of 10^?9?10^?8 cm³ (STP) cm/(cm²·s cm Hg)—lower than those of the corresponding SiMe₃-containing polymers. © 1993 John Wiley & Sons, Inc.     

Polymerization behavior of N-(p-vinyl)phenylacrylamide

The polymerization behavior of N-(p-vinyl)phenylacrylamide, synthesized from p-aminostyrene and acryloyl chloride by means of the Schotten-Baumann reaction was studied. Due to a marked difference in electron density between the two double bonds, this monomer provided soluble polymers by both cationic and anionic polymerization procedures, the cationic and anionic polymers mainly carrying, as side chains, the acrylamide and styrene moieties, respectively. The polymerization behavior of the residual double bonds was also investigated for both polymers, leading to crosslinked, insoluble products.     

Reaction of p‐toluenesulfonyl isocyanate with polymers having amide moieties and hydrolysis of the obtained polymers

The chemical modification of polymers having amide moieties was carried out with p‐toluenesulfonyl isocyanate. The resulting polymers revealed high hydrolytic character. For example, poly(acrylamide) was refluxed with an excess amount of p‐toluenesulfonyl isocyanate in THF for 50 h to obtain a structurally modified polymer in 76% yield, whose sulfonylurea functionality was 100%. The resulting polymer was subjected to hydrolysis in a 1 M NaOH solution at 50 °C to convert 90% of the sulfonylurea in the side chain to the carboxylic acid moieties. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3440–3449, 2000     

Synthesis and characterization of isomeric cis- and trans-pyrrone model compounds

Isomeric cis- and trans-imidazopyrrolones, obtained from the reaction of pyromellitic di-anhydride and o-phenylenediamine, were prepared as models for pyrrone polymers. The characterization of these model compounds, which represent the repeat unit of the completely cyclized polymer, provided information which could not be obtained by studying the polymer itself. Isomerism was proven by the nuclear magnetic resonance spectra of soluble ester-benzimidazole derivatives. This study indicated that a single band around 1755 cm^?1 should appear in the infrared spectrum of the completely cyclized polymer. The high melting points of the model imidazopyrrolones indicate the extreme thermal stability to be anticipated from perfectly formed pyrrone polymers.     

Synthesis of planar poly(p-phenylene) derivatives for maximization of extended π-conjugation

Described is the synthesis of a ladder polymer with a poly(p-phenylene) (PPP) backbone. The main PPP backbone was synthesized via palladium-catalyzed coupling of an arylbis(boronic ester) with an aryl dibromide. Imine bridges, formed by exposure of the polymer to trifluoroacetic acid, are used to force the consecutive units into planarity. The bridging units are sp² hybridized thus allowing for greater π-electron flow between the consecutive phenyl units by lowering the band gap between the hydroquinoidal and the quinoidal forms of the phenylene backbone. When the bridges are n-dodecyl substituted, the fully planar structures (with Mn < 5 000) are soluble in hot chlorobenzene from which flexible free standing films can be cast. The n-butyl substituted polymers and the higher molecular weight n-dodecyl substituted polymers are soluble in CH₂Cl₂/trifluoroacetic acid mixtures. The optical spectra of the planar systems are compared to that of the parent nonplanarized polymers, some analogous planar oligomers, and oligo(p-phenylenes).     

High intrinsic conductivity in ladder type polymers: Pyrolyzed BBB

Through electrical conductivity and ESR measurements of heat treated BBB-rigid-rod ladder polymers, we provide evidence for the existence of an irreversible transformation to another cross-linked ladder polymer with high intrinsic conductivity. The transformation occurs at a pyrolysis temperature, T_p ? 680°C. The results suggest a novel transport mechanism.     

Precise architecture of 1:1 alternating copolymers between germylenes and p-benzoquinone derivatives: First clear- cut evidence of biradical mechanism in polymerization chemistry

Germylenes bearing a bulky amide substituent have been copolymerized with various p-benzoquinone derivatives without any added catalyst to give novel class of germanium-containing polymers having a tetravalent germanium unit and a p-hydroquinone unit alternatingly in the main chain (“oxidation-reduction alternating copolymerization”). The resulting copolymers have high molecular weight (Mw>5.5×10⁴) and are soluble in common organic solvents. A novel biradical mechanism involving a germyl radical and a semiquinone radical is proposed on the basis of ESR analysis of the propagating polymer end as well as trapping experiments using a disulfide or TEMPO radical.