Copolymerization of some epoxides by coordination-type catalysts

Copolymerizations of tritiated phenyl glycidyl ether with p- and m-methoxy, p-methyl, and p-chloro analogs, as well as with propylene oxide and epichlorohydrin are reported. The relative reactivities indicate greater Lewis acid character for triethylaluminum–water than for diethyl-zinc–water or ferric chloride–propylene oxide catalyst systems. The copolymerization of the PGE analogs is promoted by electron-donor groups and retarded by electron-withdrawing groups.     

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.     

Reactivity of polymer substituents. Aminolysis of p-nitrophenyl ester residues attached to various polymer backbones

Styrene, methyl acrylate, and N,N-dimethylacrylamide were copolymerized with small proportions of p-nitrophenyl acrylate or p-nitrophenyl esters of CH₂?CHCONH(CH₂)_nCOOH (n = 1,3,5). The aminolysis of these copolymers in dioxane and chlorobenzene solution was compared with the corresponding reaction of low molecular weight analogs. The ratio of the reactivity of the polymer substituent and its analog was found to be insensitive to the nature of the amine but strongly dependent on the nature of the polymer backbone. Poly(dimethylacrylamide) chains carrying active ester substituents were in some cases much more reactive than their analogs due to the activating effect of the dimethylamide groups. In the case of the p-nitrophenyl acrylate–styrene copolymer, the aminolysis exhibited a dispersion of the rate constant due to its sensitivity to stereoisomerism in the vicinity of the active ester, but no similar effects were observed with the other copolymers.     

The synthesis and solution properties of some rigid-chain,water-soluble polymers: Poly[N,N′-(sulfo-phenylene)phthalamide]s and poly[N,N′-(sulfo-p-phenylene)pyromellitimide]

Poly[N,N′-(sulfo-phenylene)phthalamid]es and poly[N,N′-(sulfo-p-phenylene)pyromellitimide] were prepared in water-soluble form and were found to have unique solution properties, similar in some respects to xanthan. The polymer most investigated, poly[N,N′-(sulfo-p-phenylene)terephthalamide] (PPT-S), is produced as the dimethylacetamide (DMAC) salt by the solution polymerization of 2,5-diaminobenzenesulfonic acid with terephthaloyl chloride in DMAC containing LiCl. The isolated polymer requires heating in water to dissolve; the resulting cooled solutions are viscous or gels at concentrations as low as 0.4%. They are highly birefringent, exhibit circular dichroism properties, and are viscosity-sensitive to salt. Solutions of this polymer mixed with those of guar or hydroxyethyl cellulose give significantly enhanced viscosity. The polymer is relatively low molecular weight, ca. 5000 estimated from viscosity data. Some meta and para isomeric analogs of PPT-S were prepared; these polymers have similar properties except they are more soluble in water, and higher concentrations are required to obtain significant viscosity. Poly[N,N′-(sulfo-p-phenylene) pyromellitimide] (PIM-S) was prepared similarly from 2,5-diaminobenzenesulfonic acid and pyromellitic dianhydride. Its aqueous solution properties are similar to those of PPT-S. It appears that these relatively low-molecular-weight rigid-chain polymers associate in water to form a network that results in viscous solutions at low concentrations.     

Structure–property relationships in polyamides containing cyclohexylene or phenylene structures

Polyamides were prepared from linear, aliphatic dicarboxylic acids of six to twelve carbon atoms with 1,4-cyclohexanebis(methylamine), 1,4-cyclohexanebis (ethylamine), p-xylylenediamine, and p-phenylenebis(ethylamine). Melting points, glass transition temperatures, densities, and moisture regains were compared for the polymers to determine the relative effect of the cyclohexylene and phenylene linkages. While polyamides containing the trans-cyclohexylene group possessed higher glass transition temperatures than their aromatic counterparts, melting behavior was not as consistent. The odd-even rule, which states that polyamides with an even number of methylene linkages between the ring and the functional group melt higher than those with an odd number of such linkages, was violated in the cycloaliphatic systems. The T_g of ring-containing polyamide fibers was not dependent solely upon ring concentration, but was influenced by the molecular fit of the ringed intermediate in the polymer chains. Molecular fit appears to affect the T_g and melting point of alicyclic polyamides to a greater extent than the aromatic analogs. Differences in T_g, both within and among the polymer series, was not explained by either density or the degree of crystallinity.     

The heat capacity of solid poly(p-xylylene) and polystyrene

The constant-pressure heat capacity C_p of poly(p-xylylene) (PPX) has been measured from 220 to 625 K by differential scanning calorimetry. The constant-volume heat capacities C_v of both, PPX and its isomer polystyrene (PS) have been interpreted in the light of literature data on full normal-mode calculations for PS and estimates from low-molecular-weight analogs for PPX for the 39 group vibrations. Nine skeletal vibrations were used in this discussion with characteristic temperatures θ₁ and θ₃ of 534.5 and 43.1 K for PS. It was also possible to calculate a heat capacity contribution of a phenylene group within a polymer chain. Single 48-vibration θ₁ temperatures of 3230 K for PS and 2960 K for PPX are sufficient to describe C_v above 220 K. Below 140 K, PS heat capacity shows deviations from the Tarasov treatment.     

Preparation of Polymeric Analogs of Tetramethylurea and Their Use as Liquid-Liquid Phase-Transfer Catalysts

Polymeric analogs of tetramethylurea were prepared by free-radical polymerization of N,N,N'-trimethyl-N'-p-vinylbenzylurea and copolym-erization of this monomer with styrene. These polymers are soluble in toluene and have the ability to extract alkali metal ions such as lithium, sodium, and potassium. Moreover, these polymers act as phase-transfer catalysts for typical S _N 2 reactions, although the monomeric analogs tetramethylurea and N,N,N'-trimethyl-N'-benzylurea do not. A plausible mechanism for these catalytic reactions is proposed.     

Conducting polymers. I. Electrical conductivity of poly(bis-p-phenylenediaminosulphoxide)

Poly(bis-p-phenylenediaminosulphoxide) was prepared by Michael addition of p-bis-N-sulphinylphenylenediamine with p-phenylenediamine at 150°C. Thermal and electrical behaviors of the polymer have been studied. The polymer is found to have increased conductivity possibly due to the participation of lone pairs of electrons on nitrogen and sulphur atoms with σ bond of the macrochain. Thermogravimetric analysis indicates that the polymer is fairly stable than other conducting polymers up to 200°C. The activation energy of the polymer was measured and found to be 13 kcal mol^?1.     

Thermoresponsive conductivity of poly(N‐isopropylacrylamide)/potassium chloride gel electrolytes

A series of thermoresponsive polymer gel electrolytes (PGEs) based on poly(N‐isopropylacrylamide) in aqueous potassium chloride was synthesized by radiation‐induced polymerization and gelation using γ rays from a ⁶⁰Co source. The electric conductivity and swelling properties of the PGE were determined as a function of temperature. It was found that the electric conductivity of the PGE depended strongly on the swelling ratio; most notably, it changed drastically near the volume phase‐transition temperature of the PGE. The temperature/conductivity profile of the PGE exhibits a maximum peak at a certain temperature that is defined as the maximum conductivity temperature (T_max). The T_max of all of the PGEs prepared by low‐dose irradiation agreed with the temperature, near the end of the volume phase transition, where the PGE was completely shrunken. Consequently, the conductivity of gels should provide a good method with which the totally shrunken temperature of the thermoresponsive gels can be monitored with good temperature precision. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 134–141, 2002     

Four-center type photopolymerization in the solid state. IV. Polymerization of α,α′-dicyano-p-benzenediacrylic acid its derivatives

The solid-state photopolymerization of α,α′-dicyano-p-benzene diacrylic acid (p-CBA) series has been studied. p-CBA, its esters, amide, and a few other cyano derivatives were prepared and new polymers were obtained from p-CBA alkyl esters on irradiation of ultraviolet or visible light. Though the polymerization behavior differs with each monomer, polymerization proceeds in essentially the same manner as in the 2,5-distyrylpyrazine (DSP) and p-benzenediacrylic acid (BDA) series: the reaction proceeds topochemically forming polymer with a cyclobutane ring in the main chain. Properties of high polymer are typical of cyclobutane-containing polymer. That is, they are highly crystalline with high melting temperature and a limited solubility. The study on this series of compounds, as well as the DSP and p-BDA series, supports the generalization that solid-state dimerization can be extended to solid-state photopolymerization of compound having two dimerizable units in a molecule.     

Poly(P-phenylene sulfide) hexafluoroarsenate: A novel conducting polymer

Poly(p-phenylene sulfide) (PPS) is a melt- and solution-processible polymer which on treatment with AsF₅ forms a blue-black material with a conductivity of 1–10 Ω^?1 cm^?1. Thermopower measurements indicate that the resulting polymer is p type, consistent with partial oxidation of the PPS by the AsF₅. The rate and extent of this doping process prove to be particularly sensitive to the degree of crystallinity of the starting polymer. There is also evidence of crosslinking of the polymer chains during the reaction with AsF₅. The details of both the chemistry and physics of the doping of PPS and several of its derivatives are presented.     

Characterizing polymer macrostructures by identifying and locating microstructures along their chains with the kerr effect

In this brief report, we demonstrate that Kerr effect measurements, which determine the excess birefringence contributed by polymer solutes in dilute solutions observed under a strong electric field, are highly sensitive to and capable of determining their microstructures, as well as their locations along the macromolecular backbone. Specifically, using atactic triblock copolymers with the same overall composition of styrene (S) and p-bromostyrene (pBrS) units, but with two different block arrangements, that is, pBrS₉₀-b-S₁₂₀-b-pBrS₉₀ (I) and S₆₀-b-pBrS₁₈₀-b-S₆₀ (II), which are indistinguishable by NMR, we detected a dramatic difference in their molar Kerr constants (_mK), in agreement with those previously estimated. Although similar in magnitude, their Kerr constants differ in sign, with _mK(II) positive and _mK(I) negative. In addition, S/pBrS random and gradient copolymers synthesized by reversible addition-fragmentation chain-transfer (RAFT) polymerization exhibit a heretofore unexpected enhanced enchainment of racemic (r) pBrS-pBrS diads. Comparison of their observed and calculated _mKs suggests that the gradient S/pBrS copolymers possess an unanticipated additional gradient in stereosequence that parallels their comonomer gradient, that is, as the concentration of pBrs units decreases from one end of the copolymer chain to the other, so does the content of r diads. This conclusion could only be reached by comparison of observed and calculated Kerr effects, which access the global properties of macromolecules, and not NMR, which is only sensitive to local polymer structural environments, but not to their locations on the copolymer chains. Molar Kerr constants are characteristic of entire polymer chains and are highly sensitive to their constituent microstructures and their distribution along the chain. They may be used to both identify constituent microstructures and locate them along the polymer chain, thereby enabling, for the first time, characterization of their complete macrostructures. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

Polymer-Supported Tetrabromooxomolybdate(V): A New Type of Catalyst for Oxidation by t-Butyl Hydroperoxide

Tetrabromooxomolybdate(V) was immobilized in alkylammonium cation-type polymers obtained by the reaction of poly(p-chloromethyl-styrene-co-divinylbenzene-co-styrene) (abbreviated CMS) with amines and derived from poly(p-vinylpyridine) and poly(p-vinylpyridine-co-divinylbenzene). These immobilized polymers were active catalysts for the oxidation of alcohols and epoxidation of olefins with t-butyl hydroperoxide (abbreviated t-BuOOH). Among these polymers, we could find a polymer catalyst showing specificity, which was obtained by immobilization of tetrabromooxomolybdate(V) in the polymer derived from the reaction of CMS with trimethylamine. This immobilized polymer does not catalyze epoxidation of olefins but catalyzes oxidation of alcohols with t-BuOOH. Ammonium tetrabromooxomolybdate(V) complex was stabilized by the immobilization in the polymers, and it was found that the reactivity of the active group is due to the microenvironment supplied by the polymer chain.     

Conjugated polymers containing phenothiazine moieties in the main chain

Several conjugated polymers containing phenothiazine moieties in the main chain were synthesized by Knovenagel or Wittig condensations. The polymers were identified and characterized by ¹H‐NMR, IR, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), UV‐vis and fluorescent (FL) spectra. Results indicated that the m‐polymer, which was prepared from the polycondensation of N‐octyl‐3,7‐diformylphenothiazine with m‐phenylene diacetonitrile, is the most thermally stable one in all the polymers synthesized. While, the p‐polymer, which was prepared from the polycondensation of N‐octyl‐3,7‐diformylphenothiazine with p‐phenylene diacetonitrile, is the most thermally instable one. The introduction of a cyano group made the absorption and emissive maxima red‐shift from 429 and 537 nm for the Ph‐polymer to 465 and 597 nm for the p‐polymer respectively. The quinoid structure formation allows the p‐polymer to have a lower band gap than any other polymers. Emissive spectra of all these polymers in tetrahydrofuran (THF) solution have a narrow half‐peak width. Copyright © 2006 John Wiley & Sons, Ltd.     

The effects of monoepoxide chain termination and their derived soluble fractions on the structure‐property relationships of controlled epoxy networks

A new series of monoepoxide terminated controlled epoxy networks (CENs) and a corresponding soluble fraction polymer (SFP) were prepared to further investigate the effects of chain termination on epoxy thermoset structure‐property relationships. CENs having an initial molecular weight between crosslinks (M_c,i) of ～3000 g/mol using phenylglycidyl ether (PGE) as the chain terminator have thermal and mechanical properties consistent with previously studied monophenol terminated CENs. Glass transition temperature (T_g) decreases monotonically with PGE concentration (ε), whereas fracture toughness decreases sharply at a critical PGE concentration (ε_c). A PGE terminated SFP was prepared corresponding to the soluble fraction expected for the CEN composition at ε_c. The SFP behaves as a weak antiplasticizer in these epoxy thermosets; T_g is reduced and follows the inverse rule of mixtures, and fracture toughness is slightly reduced. By difference it is inferred that most of the deterioration of epoxy thermoset properties resulting from incorporation of chain terminators above ε_c is a result of the presence of nonelastically active pendant chains and by the increase in M_c. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 72–79, 2009     

Synthesis,characterization, and properties of regioregular conjugated polymers containing quaterthiophene and an acceptor repeating units

Novel donor–acceptor type polymers consisting of alternating quaterthiophene and an electron withdrawing moiety, pyrazinyl or pyridinyl, have been prepared using Stille coupling approach with moderate yields. The polymers were highly soluble in common organic solvents such as tetrahydrofuran and chloroform. The structure and optical properties of the polymers were characterized by NMR, UV‐vis and fluorescence spectroscopy, and cyclic voltammetry, respectively. The polymer having pyrazine unit exhibited a red‐shift in both absorption and emission in comparison with those analogs containing pyridine because of strong electron withdrawing character of the pyrazinyl group. The polymer containing pyrazinyl as acceptor units also depicted decrease in its optical and electrochemical bandgap relative to those polymers containing 2,5‐ or 2,6‐pyridine moieties. The electrochemical behavior showed facile n‐doping and p‐doping properties of those polymers consisting of alternating quaterthiophene and the acceptor moiety. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2163–2171, 2009     

Synthesis and thermogravimetric analysis of diol-linked tetrameric hexaphenyldichlorophosphonitrile polymers

Several high molecular weight polymers have been prepared from the reactions of hexaphenyldichlorophosphonitrile tetramer with p,p′-biphenol, 4,4′-oxydiphenol, resorcinol, and benzidine. A simple fractionation procedure yielded samples of the biphenol-linked polymer with molecular weights of approximately 500,000. DTA and TGA studies of this polymer in a variety of environments indicate thermal degradation is initiated in the phosphonitrile ring.     

Polybenzopinacolones. Acid-catalyzed rearrangement of aromatic polybenzopinacols

Polybenzopinacols resulting from the photocondensations of p,p′-dibenzoyldiphenyl ether, p,p′-dibenzoyldiphenylmethane, and p,p′-dibenzoyl-1,2-diphenylethane were rearranged in sulfuric acid–dioxane solutions. The inherent viscosities of the polybenzopinacolones did not differ significantly from the inherent viscosities of the polybenzopinacols after rearrangement. A model compound study by NMR and infrared methods indicated that the polymer chain was probably the main migrating group for each of the polymer rearrangements.