Synthesis and free radical ring-opening polymerization of 2-methylene-4-phenyl-1,3-dioxolane

The cyclic ketene acetal, 2-methylene-4-phenyl-1,3-dioxolane ( 3 ), was shown to undergo free radical ring-opening polymerization to produce the polyester, poly[γ-(β-phenyl)butyrolactone]. The monomer 3 was synthesized by an acetal exchange reaction of chloroacetaldehyde dimethyl acetal with styrene glycol in an 87% yield followed by dehydrochlorination of the resulting cis and trans-2-chloromethyl-4-phenyl-1,3-dioxolane ( 2 ) with potassium tert-butoxide in tert-butyl alcohol in a 70% yield. 3 was shown to undergo essentially quantitative free radical ring-opening at all temperatures from 60–150°C and also nearly complete regioselective ring-opening with cleavage to give the more highly stable secondary benzyl free radical. Even in free radical copolymerization with styrene, methyl methacrylate, vinyl acetate, or 4-vinylpyridine, 3 gives essentially complete ring opening to introduce an ester groups into the backbone of the addition copolymer. The structures of the polymers were established by elemental analysis and ¹H and ¹³C NMR spectroscopy.     

Synthesis and polymerization of N-trimethylsilylacrylamide: A hydrophobic acrylamide

N-Trimethylsilylacrylamide (TMSAm), a hydrophobic acrylamide, has been synthesized and characterized. The monomer could be polymerized in benzene by 2,2′-azoisobutyronitrile or benzoyl peroxide to poly(TMSAm). The silylated polymer was characterized with ¹H NMR. Poly(TMSAm) is stable in the absence of moisture. It could be quantitatively hydrolyzed to polyacrylamide under mild conditions. The monomer has been copolymerized with styrene in benzene by benzoyl peroxide to yield polymers which on hydrolysis give copolymers of acrylamide and styrene.     

New Polymers Based on Fluorenylidene‐Linked Conjugated Oligo(p‐phenylene)s

New thermally stable, fluorescent copolymers consisting of fluorenylidene‐linked conjugated oligo(p‐phenylene) segments are presented. The copolymers have been prepared by the palladium‐catalyzed Suzuki polycondensation method. The copolymers obtained are found to be soluble and easily processable from conventional organic solvents such as chloroform, toluene or tetrahydrofuran, and have been characterized by ¹H and ¹³C NMR spectroscopy, FT‐IR spectroscopy and elemental analysis. The degree of polymerization has been estimated by gel permeation chromatography (GPC). The thermal properties of the copolymers were characterized by differential scanning calorimetry (DSC). The optical properties of the polymers have been investigated in solution by UV/VIS spectroscopy.     

Synthesis and characterization of block copolymers containing cationic blocks

Poly(ethylene glycol)-poly(diallyldimethylammonium chloride) block copolymers containing nearly equal number of both monomer units were synthesized by free radical polymerization using macroazoinitiators of different molecular weights obtained from 2,2'-azoisobutyronitrile (AIBN) and poly(ethylene glycol). Characterization by elemental analysis, gel permeation chromatography and ultracentrifugation proved the formation of ABA-block copolymers. Furthermore, the polymers were characterized by DSC and viscosimetric measurements. The block copolymers lowered the surface tension of their aqueous solutions. Cross-sectional areas A_min of some of the polymers were calculated from surface tension vs. concentration isotherms. The results indicate the PEG-blocks to be adsorbed at the air-water interface, whereas the poly-(DADMAC)-block is completely present in the aqueous phase. The block copolymers are powerful stabilizers in emulsion polymerization of styrene, resulting in monodisperse cationic latexes.     

Chiral methacrylic polymers containing permanent dipole azobenzene chromophores. 13C NMR spectra and photochromic properties

Dynamics in solution and photochromic properties of radical copolymers of (S)-4-[N-(2-methacryloyloxyethyl)-N-(2-methylbutyl)]amino-4′-cyanoazobenzene with butyl methacrylate were investigated. ¹³C NMR and 2D heteronuclear correlated (HETCOR) spectroscopy allowed assignment of ¹³C NMR signals and evaluation of main chain tacticity. ¹³C relaxation times T₁ evidenced a rather limited mobility of azobenzene chromophores. Mobility increases with increasing content of butyl methacrylate units, that acts as an internal plasticizer. The limited mobility of the spacer between azobenzene and methacrylate groups is attributed to an interaction between carbonyl oxygen and aminic nitrogen stabilized by the internal charge transfer from the amino to the cyano group. Trans to cis photoisomerization rates turned out to be independent of molecular weight and chemical composition of the investigated photochromic polymers, whereas cis to trans thermal isomerization rates increase with the content of aromatic units. These data suggest that photo- and thermal isomerization processes imply an in-plane inversion and an out-of-plane rotation of one of the phenyl rings of the azobenzene chromophores, respectively. Preliminary second harmonic generation measurements indicate that the investigated polymers are endowed with significant non-linear optical properties.     

Zwitterionic polysoaps with reduced density of surfactant side groups

Several zwitterionic polymers were prepared by radical homopolymerization of surfactant monomers which bear diallyl, diene or vinylcyclopropane moieties. These polymer systems were complemented by alternating copolymers of appropriate zwitterionic vinyl compounds. Thus, polymers with reduced (as compared with simple vinylic homopolymers, or statistical copolymers) and well defined density of surfactant side groups are obtained. The solubilities found for these polymers are dominated by polymer geometry rather than by the balance of hydrophilic and hydrophobic fragments, thus corroborating a “main-chain spacer” model proposed recently. All water-soluble polymers exhibit characteristic features of classical polysoaps, as shown by surface tension measurements and by solubilization of hydrophobic dyes. In contrast, the water-insoluble copolymers are capable to form stable monolayers at the air-water interface.     

Methacrylic polymers containing permanent dipole azobenzene chromophores spaced from the main chain. 13C NMR spectra and photochromic properties

Dynamics in solution and photochromic properties of radical copolymers of 4-(4-oxy-4′-cyanoazobenzene)but-1-yl methacrylate, 6-(4-oxy-4′-cyanoazobenzene)hex-1-yl methacrylate, and 8-(4-oxy-4′-cyanoazobenzene)oct-1-yl methacrylate with (–)-menthyl methacrylate were investigated. ¹³C NMR and 2D HETCOR spectroscopy allowed assignment of ¹³C NMR signals and evaluation of main chain tacticity. ¹³C T₁ relaxation times evidenced a rather limited mobility of the azobenzene chromophores when inserted in polymer macromolecules. Mobility increased with increasing the length of the polymethylene spacer that acted as a flexible joint between the aromatic chromophore and polymer backbone. Both the trans to cis photoisomerization and the cis to trans thermal isomerization processes showed a small dependence on monomer structure and chemical composition of the investigated photochromic polymers. These data seem to suggest an appreciable contribution of the in-plane inversion mechanism to both isomerization processes of the azobenzene chromophores. The absence of appreciable dichroic bands in the copolymer CD spectra and the negative results obtained in preliminary second harmonic generation measurements are discussed in terms of the polymer structural features.     

Mixed (electronic and ionic) conductive solid polymer matrix, 1. Synthesis and properties of poly(2,5,8,11,14,17,20,23-octaoxapentacosyl methacrylate)-block-poly(4-vinylpyridine)

Poly(2,5,8,11,14,17,20,23-octaoxapentacosyl methacrylate)-block-poly(4-vinylpyridine) semicomb polymers were synthesized using anionic living polymerization techniques. The polymers are white, powdery materials and were characterized by ¹H and ¹³C nuclear magnetic resonance spectroscopy and gel-permeation chromatography. The polymers display monomodal molecular weight distributions which are relatively narrow. The block copolymers show microphase separation as indicated by the presence of two glass transition temperatures (T_g), a soft (oxyethylene) phase T_g is observed between ?60°C and ?45°C and a hard (4-vinylpyridine) phase T_g is observed between 135°C and 150°C. The soft oxyethylene phase has been doped with LiClO₄ to obtain ionic conductors with electrical conductivities around 5 · 10^?6 S · cm^?1 at 25°C and the hard 4-vinylpyridine phase has been complexed with 7,7,8,8-tetracyano-1,4-quinodimethane (TCNQ, 2,5-cyclohexadiene-1,4-diylidenedimalonitrile) to obtain electronic conductivities around 10^?6 S · cm^?1 at 25°C. The mixed (electronic and ionic) conductivities are intermediate between the ionic and electronic conductivities. Higher electronic conductivities (≈ 10^?5 S · cm^?1 at 30°C) are obtained for the polycation TCNQ^?/TCNQ⁰ complexes.     

Photoreactive chiral liquid-crystalline side-group copolymers containing azobenzene mesogens

A series of liquid-crystalline copolymers 1 with a chiral azobenzene moiety as photoreactive mesogenic unit was prepared. The polymers were fractionated and the mesophase behaviour of the high- and low-molecular weight fractions was examined. The copolymers display smectic A and cholesteric phases. For the cholesteric phases the pitch of the helix was determined, which ranges from 3 to 20 μm. Stable monolayers at the air-water interface were obtained from two monomers and one of the homopolymers. Multilayer assemblies of the azobenzene-containing polymers can be used to study photo-induced order/disorder transitions.     

Tactic copolymers derived from poly(methacrylohydrazide) and functional α-amino acids

Lactic acid and N-tert-butoxycarbonyl protected L-alanine, L-histidine and L-serine were condensed with syndiotactic poly(methacrylohydrazide) (1) in aqueous solution in the presence of N-ethyl-N′-(3-dimethylaminopropyl) carbodiimide. By incomplete conversion of (1) copolymers 4a – d were obtained containing methacrylohydrazide monomeric units. By complete conversion with L-histidine and L-serine simultaneously, copolymers 5 containing both amino acid moieties were obtained. The N-tert-butoxycarbonyl protecting group was removed from the polymers by acidolysis. This reaction was followed by CD spectroscopy. All polymers were characterized by ¹H and ¹³C NMR spectroscopy.     

Microstructure of styrene-methacrylic acid and styrene-acrylic acid copolymers, 4. 1H NMR study of phenyl rings in methylated styrenemethacrylic acid and styrene-acrylic acid copolymers

The sequence distribution in methacrylic acid-styrene and acrylic acid-styrene copolymers of various composition prepared in benzene and emusion were studied by using the aromatic proton region in the ¹H NMR spectra of methylated copolymers. A digital computer was used to resolve overlapping peaks, and one Lorentzian and two Gaussian curves were fitted for their approximation. The study of random copolymers shows that styrene sequences as small as two and three units are contained. The run numbers and number-average sequence lengths of styrene calculated for emulsion methacrylic acid-styrene and acrylic acid-styrene copolymers show that these copolymers do not have long sequences of styrene units.     

Synthèse,polymérisation et copolymérisation d'un dérivé 2h-benzotriazolylphényl de l'acétate de vinyle

1-(4-Acetoxy)-3-(2H-benzotriazolylphenyl)vinyl acetate (4) was synthesized. The polymerization of 4 afforded polymer 5 with a relatively low molecular weight (= 2000). Copolymerizations of 4 (3,7 wt.-%) were carried out with styrene and methyl methacrylate to copolymers 6 and 7, respectively. Polymer 5 and copolymers 6 and 7 were characterized by ¹ H and ¹³ C NMR and by IR and UV spectroscopy. Their UV spectra show a strong absorption in the near UV spectrum. 4 may thus be considered as a potential comonomer for UV protection.     

Structural analysis of alkene/maleic anhydride copolymers

Structural investigations on maleic anhydride (MAn) copolymers with ethene, propene and styrene, their products of hydrolysis, and their methyl half-esters by means of ¹³C NMR spectroscopy are presented. The spectra of 2,3-diethylsuccinic acid and its anhydrides in the erythro- and threo-configuration and of butylsuccinic acid and its anhydride were obtained and compared with the spectra of the copolymers. In each case the results show the formation of both threo(trans)- and erythro(cis)-structures. At a polymerization temperature of 60°C the proportions were 88% threo to 12% erythro for ethene/MAn copolymers and 80% threo to 20% erythro for propene/MAn copolymers, a ratio which was confirmed also by the hydrolyzed forms. Copolymerization at 150°C leads, in the case of propene/MAn, to 67% threo and 33% erythro. The production of ethene/MA copolymer via the copolymerization of ethene and fumaric acid half-ester and its saponification to ethene/fumaric acid leads to a ratio of 38% threo to 62% erythro. These results are in accordance with the thermal stabilities of the configurations. In the case of styrene/MAn copolymer it is not possible to obtain a unique interpretation of the configurations from the spectra. For the conversion of propene/MAn and styrene/MAn copolymers by means of methanol to half-esters it can be derived from the ¹³C NMR spectra how many of the half-ester moieties are obtained in the neighbourhood of the methyl and phenyl groups, respectively, of the olefin.     

New water soluble cellulose esters synthesized by an effective acylation procedure

Non‐ionic cellulose esters were synthesized in homogeneous phase (N,N‐dimethyl acetamide/LiCl) with mixed oxacarbonic acid/p‐toluenesulfonic acid anhydrides. This effective synthetic method yields the pure carboxylic acid esters within the wide range of the degree of substitution (DS) from 0.4 to 3.0. The polymers were characterized by means of FTIR and ¹³C NMR spectroscopy as well as by means of ¹H NMR spectroscopy of the additionally peracetylated samples. The polymers are water soluble starting with a DS of 0.4 and they are even soluble in acetone and ethanol at higher DS values. They are thermally stable up to 325°C.     

Diastereotopic Styrene Arrangement in the Heterosequences of Random Styrene‐Ethylene Copolymers

Random styrene‐ethylene copolymers have been synthesized by the hydrogenation of styrene‐butadiene copolymers. The samples were characterized by ¹³C NMR spectroscopy, X‐ray powder diffraction, thermal analysis, and Fourier transform IR (FTIR) spectroscopy. In the ¹³C NMR spectra, the resonance of the methylene carbon next to a methine bearing a phenyl group presents splitting due to its diastereotopic positions with respect to the phenyl substituents of the second and third inserted styrene units. A definitive assignment of the resonances of the SEES sequences (S = styrene, E = ethylene) was obtained by synthesis of a suitable model compound: 5,10‐diphenyl‐pentadecane. X‐ray powder diffraction and thermal analysis show that these samples are amorphous. This is probably due to the shortness of the ethylene and styrene sequences in the copolymers. DSC thermograms show a single glass transition, at a intermediate temperature, between the T_g values of polystyrene and polyethylene, depending on the styrene content in the chain. FTIR spectra indicate the presence of styrene sequences in an isotactic arrangement.

     

3- and 4-dimethylaminobenzyl acrylate and methacrylate and their polymers

3- and 4-dimethylaminobenzyl acrylates ( 3 and 4 ) and methacrylates ( 1 and 2 ) were prepared and their densities, IR and NMR spectra are recorded. In order to evaluate their reactivity towards benzoyl peroxide, the rate constants of the reaction of benzoyl peroxide with 3- and 4-dimethylaminobenzyl alcohols and 3- and 4-dimethylaminobenzyl acetates were determined. The reactivity of the esters prepared in this work appeared to be weaker than that of an N-aryl-N-alkylaminoalkyl methacrylate. The blocks of homopolymers of these esters and of their copolymers (mole ratio 1:1) with styrene and methyl methacrylate are crosslinked. Both homopolymers and copolymers of 1 and 3 are more stable in polar solvents and on heating than polymers of 2 and 4 . The copolymerization parameters of 1 and 2 with styrene are close to the copolymerization parameters of methyl methacrylate with styrene.     

New crown ether resins prepared by cationic template polymerization

The synthesis of several dibenzo-18-crown-6 derivatives, and their acid catalyzed incorporation into crosslinked styrene and 4-methoxystyrene based copolymers is described. Some of these reactions were carried out in the presence of chiral ammonium cations acting as non-covalent templates. The polymers have been characterized by IR, and by ¹H and ¹³C solution state and magic angle spinning NMR.     

Über polymere 4-vinylimidazolide und deren verwendung als acylierungsreagenzien

Several copolymers of 4(5)-vinylimidazole ( 1a ) containing different amounts of divinyl-benzene (DVB) as crosslinking agent and also copolymers of 1a (crosslinked, 4 mol-%) with styrene, 4-vinylpyridine, 1-vinylimidazole, or 4-vinylbenzoic acid were obtained by radical polymerisation. The pendant imidazole-groups of all of these polymers could be acylated in their 1-position. The swellability of the resulting polymeric N-acylated imidazoles in suitable solvents was investigated. They were used for the acylation of amines and alcohols, variing the mole ratio reactive polymer/substrate, the reaction time, and the solvent. A gradual reacitivity was found for the reaction with low molecular mass compounds according to the nucleophilicity of the substrates. Ethanolamine could be selectively N-acetylated and in the case of the mono-trifluoroacetylation of hexamethylenediamine significantly high yields of mono-acylated product were obtained. After the reaction the polymers could be regenerated without any loss of activity.     

Saccharide polymers, 2. Synthesis and polymerization of exo-glucal derivatives

Unsaturated glucopyranose derivatives such as 1,2,3,4-tetra-O-acetyl-6-desoxy-β-D -xylo-hex-5-enopyranose (3) and 1,2,3,4-tetra-O-benzoyl-6-desoxy-β-D -xylo-hex-5-enopyranose (6) , briefly called “Ac-exo-glucal (3) ” and “Bz-exo-glucal (6) ”, were synthesized. These exo-cyclic sugar vinyl ethers were investigated in polymerization reactions. The corresponding “saccharide polymers”, homo- and copolymers, were synthesized under free radical conditions. The structures and the compositions of the soluble “saccharide polymers” were established by elemental analysis, ¹H and ¹³C NMR, and FTIR spectroscopy. Characterization of the polymers, like molecular weights and optical rotations are reported. Saccharide polymers with different sugar content and low as well as high molecular weights were obtained.     

13C NMR characterization of a new ethylene-propene copolymer obtained with a high yield titanium catalyst

A detailed microstructural characterization of ethylene-propene copolymers, obtained with a high yield Ti-catalyst and showing elastomeric properties, was carried out by ¹³C NMR spectroscopy. These copolymers show no inversions in propene insertion, a tendency to form blocks of ethylene and propylene, and the presence of both isotactic and atactic blocks of propylene. Furthermore, in these polymers the reactivity ratio product (r₁ · r₂) and the experimental versus calculated triad distribution point to the presence of components which are heterogeneous with respect to the monomer distribution and composition. ¹³C NMR analysis of fractions, separated by hexane and ether, supports the above hypothesis.