Poly(vinyl ether)s and poly(propenyl ether)s containing mesogenic groups: A new class of side-chain liquid-crystalline polymers

A new series of thermotropic liquid-crystalline polymers, poly(vinyl ether)s and poly(propenyl ether)s, containing the mesogen 4-methoxy-4′-hydroxybiphenyl in the side chain and different spacers between the mesogens and the backbone were synthesized and characterized by DSC and optical microscopy. Their mesomorphic behavior was compared to that of the corresponding polymethacrylates. In general the poly(propenyl ether)s showed lower transition temperatures and larger thermal stability ranges of their mesophases than the respective polymethacrylates, reflecting the effect of substituting the rigid ester bond connecting the spacer to the backbone in polymethacrylates by a more flexible ether bond. Also, poly(propenyl ether)s showed more ordered mesophases than the polymethacrylates, suggesting that a better decoupling of the mesogen and polymer backbone is obtained through the ether linkage.     

Recombination luminescence of poly(arylene phthalide) films: 1. Electronic and optical features of poly(arylene phthalide)s

Features of the luminescence and absorption spectra of poly(biphenylene phthalide), poly(fluorenylene phthalide), and poly(terphenylene phthalide) films were analyzed. Experimental results obtained for these films by optical methods and thermally stimulated current spectroscopy were compared. Long-lasting afterglow emission from the films after photoexcitation was observed. Possible explanations for the observed optical and thermally stimulated processes in the poly(arylene phthalide)s were suggested in terms of reversible electronic phase transitions induced by external factors in unconjugated polymers.     

Electroluminescence in unconjugated polymers based on poly(arylene phthalide) films

We discuss the results of measurements of the optical characteristics of thin organic films of unconjugated poly(arylene ether ketone) polymer. We have observed persistent electroluminescence for this polymer. We have established an interrelationship between the polarity of the voltage applied to the experimental structure and the electroluminescence spectrum. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 45, No. 1, pp. 42–45, January–February, 2009.     

Studies on photocrosslinkable-cum-flame retardant poly(benzylidene phosphoramide ester)s

Four series of photocrosslinkable-cum-flame retardant poly(benzylidene phosphoramide ester)s were synthesized from bis(4-hydroxy-3-methyoxybenzylidene) acetone, 2,5-bis(4-hydroxy-3-methoxybenzylidene)cyclopentanone, 2,6-bis(4-hydroxy-3- methoxybenzylidene)cyclohexanone and 2,7-bis(4-hydroxy-3-methoxybenzylidene) cycloheptanone with various arylphosphorodichloridates by interfacial polycondensation using a phase transfer catalyst. The resultant polymers were characterized by gpc, FTIR, ¹H, ¹³C and ³¹P-NMR spectroscopy. Thermal behavior of the polymers was evaluated by differential scanning calorimetry and thermogravimetry. Flame retardant properties were ascertained by Limiting Oxygen Index. The photocrosslinking ability of the polymers was studied by ultraviolet spectroscopy. The crosslinking proceeds via 2π + 2π cycloaddition reaction of the benzylidene groups. The rate of crosslinking decreases with increase in the size of cycloalkanone ring, while the thermal stability increases with increase in the size of the alkanone ring. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3285–3291, 1999     

Synthesis and characterization of new telechelic poly(phenyleneoxide)s

New well-defined telechelic poly(phenyleneoxide)s (PPO's) were synthesized from 4-bromo-2,6-dimethylphenol and bi-phenolic compounds through phase transfer catalyzed aromatic nucleophilic substitution polymerization. Bisphenol-A (BPA), 4,4^′-biphenol (BP), hydroquinone (HQ) and 2,6-dihydroxynaphthalene (DHN) were employed as telechelic units. The composition analysis by proton-nuclear magnetic resonance (¹H-NMR) spectroscopy revealed that DHN was highly reactive compared to BPA and HQ, whereas BP was un-reactive in the polymerization process. The number average repeating unit (n) in telechelic PPO was estimated as n=17-19 and n=17-20 for DHN and BPA (or HQ), respectively. The reactivity of the bi-phenolic in PPO synthesis are confirmed as DHN > HQ ∼ BPA ? BP. The molecular weight determination by gel permeation chromatography (GPC) and viscosity method suggest that the molecular weight of PPO decreased drastically with increasing amount of bi-phenolic units in the feed. The GPC chromatogram of PPO showed a bi-modal distribution, clearly indicative of formation of two different types of molecular weight chains, whereas the telechelic polymers have a mono-modal distribution with a narrow polydispersity. Thermal analysis by differential scanning calorimetry revealed that telechelic polymers are highly amorphous, like PPO, and no crystallization or melting peaks were observed in the heating/cooling cycles.     

From poly(dialkylstannane)s to poly(diarylstannane)s: comparison of synthesis methods and resulting polymers

The efficiency and applicability of three different methods to synthesize polystannanes with different side chains are described. By means of dehydrogenative coupling utilizing the transition metal catalyst RhCl(PPh₃)₃ (Wilkinson's catalyst), n‐Bu₂SnH₂ reached the highest molar masses. Dehydrogenetive coupling in the presence of tetramethylethylenediamine could be best employed for (4‐n‐BuPh)₂SnH₂. Wurtz coupling using sodium in liquid ammonia was best suited for Ph₂SnCl₂. Next to the above‐mentioned educts, n‐Bu(Ph)SnX₂ (X = H or Cl (as appropriate for the particular route) was used for polymerization resulting in one of so far rare example of asymmetric polystannanes with high molecular masses. Copyright © 2011 John Wiley & Sons, Ltd.     

Recombination luminescence of poly(arylene phthalide) films: 2. Afterglow emission induced by electric excitation in poly(arylene phthalide) films

Absorption, luminescence and electroluminescence spectra of films of the unconjugated copolymer poly(arylene ether ketone) (CPAEK) were measured. Long-lasting afterglow emission was observed resulting from electro- and photoexcitation of the CPAEK films. and is possible mechanisms of generation are discussed.     

Aminosalicylate-based biodegradable polymers: Syntheses and in vitro characterization of poly(anhydride-ester)s and poly(anhydride-amide)s

Poly(anhydride-ester)s and poly(anhydride-amide)s derived from both 4- and 5-aminosalicylate acids (4- and 5-ASA) were synthesized and characterized by physicochemical methods. Thermal and solubility characteristics directly correlated to the polymer backbone composition; polymers based on 5-ASA had greater solubilities in organic solvents than polymers based on 4-ASA, and the poly(anhydride-ester)s thermally decomposed at temperatures nearly 100 °C higher than the corresponding poly(anhydride-amide)s. The polymers were self-contained, controlled-release systems that combine the drug and controlled-release mechanism into the polymer backbone. The erosion and degradation characteristics of the polymers were measured in physiologically relevant media. All polymer matrices fully degraded in media buffered to pH 7.4, whereas in acidic media (pH 1.2), all polymer matrices maintained greater than 50% mass over a 90-day time period. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3667–3679, 2003     

Synthesis and characterization of new fluorescent poly(arylene ether)s

The poly(arylene ether)s were prepared by the nucleophillic aromatic substitution polymerization of phenolphthalin and its derivatives with activated aromatic difluorides. The polymers had glass transition temperatures ranging from 210 to 240°C. Though the monomers have no fluorescence, the resulting polymers fluoresced a light green color in solid and solution states. The maximum excitation and emission wavelengths are 420 nm and 470 nm, respectively. In the polymer solutions, the fluorescence intensity decreased gradually, but the intensity was recovered by heating the polymer at 220°C for a few minutes. The fluorescent polymer had a stable radical. A model compound having the same repeating unit of the polymer was also prepared. The fluorescence properties of this model were almost the same as those of the polymers. © 1994 John Wiley & Sons, Inc.     

Synthesis and characteristics of the poly(carboxybetaine)s and the corresponding cationic polymers

Two types of carboxybetaines and their corresponding cationic monomers and polymers are synthesized in this study. Comparing the chemical shifts of the methylene groups in the cationic monomers and carboxybetaines in both ¹H- and ¹³C-NMR spectra reveal that the respective methylene groups are clearly distinguished from their chemical shifts in ¹H- and ¹³C-NMR spectra. The solubilities, moisture regain properties, and solution properties of the poly(carboxybetaine)s and cationic polymers are investigated in relation to their molecular structures. Because the cationic polymers were ionized in an aqueous solution, the cationic polymers were more soluble than the poly(carboxybetaine). For the various functional groups of poly(carboxybetaine)s and cationic polymers, the order of tendency for moisture regain is  COO >  CONH . Results obtained from the reduced viscosity for cationic poly(TMMPAMS) are reversed from that for zwitterionic poly(DMAEAPL). © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3527–3536, 1997     

Synthesis,optical absorption and fluorescence of new poly(p-phenylene)-related polymers

The synthesis and properties of soluble, conjugated polymers consisting of oligo(p-phenylene) sequences linked by ethylene, vinylene, or ethylene, units are reported. Benzene-, stilbene-, diphenylacetylene- and 1,2-diphenylethane derivatives serve as monomers and are connected by the Suzuki-coupling method. A wide range of poly-(p-phenylene)-related polymers are available by the combination of different AA/BB-type monomers in various concentrations. The optical properties of the resulting polymers can therefore be tailored. Number-average degrees of polymerization of up to X̄_n = 137 were reached under optimized conditions. Photoluminescence quantum yields of these materials in solution are nearly one.     

A new simple synthesis of poly(thiophene-methine)s

Acid-promoted polycondensation of 3,4-(ethylenedioxy)thiophene-2-carbaldehyde leads to a conjugated heavily p-doped poly(thiophene-methine), which can be dedoped leading to a low band-gap neutral polymer.     

A new class of aromatic poly(ether-ketone benzoxazole) copolymers by nucleophilic polycondensation: Synthesis and properties

A number of difluorophenyl benzoxazole (DB) monomers and 4,4′-difluorobenzophenone (DFB) were subjected to fluoro-displacement with two different phenoxides in a polar aprotic solvent. A series of novel poly(ether-ketone benzoxazole) copolymers (PAEKBOs) were more readily prepared, in which the generation of aryl-ether linkages was the copolymer forming reaction. The effects of monomer structure and polymerization conditions on the polymerization results and polymer solubility were analyzed. Copolymers 1, 2-X, 4 and 6 were obtained with high molecular weight. Copolymers 2-X and 4 showed organic solubility, especially the copolymers 2-X could dissolve in many usual organic solvents at the solid concentration of up to 20 wt%. TGA and DSC measurements confirmed that the copolymers 2-X, 4 and 6 were thermally stable up to 500 °C, and showed single enhanced T_gs and an amorphous morphology. The copolymers behaved in many respects as engineering thermoplastics. The properties and the processability of several members of the PAEKBOs offer the prospect of being candidates to substitute poly(ether-ether-ketone) (PEEK) using in a wider usage temperature range and being high performance materials for many applications as films, coatings for optical and electronic devices and gas separation membranes.     

Geminal poly(silyl ester)s: Highly labile degradable polymers

Geminal silyl ester linkages were used for the backbone construction of linear polymers, which exhibit rapid cleavage in the presence of atmospheric water. A series of poly(gem-silyl ester)s with two ester groups flanking each silicon atom were synthesized, in order to probe the effects of different silyl-substituted side-chain groups upon the physical and chemical properties. The transsilylation condensation reaction of bis(trimethylsilyl) terephthalate with dichlorodiisopropylsilane, dichlorodicyclohexylsilane, dichloromethyl-n-octadecylsilane, and dichloromethyl-4-methylphenethylsilane gave the four poly(gem-silyl ester)s with two isopropyl, two cyclohexyl, one methyl plus one octadecyl, and one methyl plus one 4-methyl-phenethyl side-chain groups per silicon, respectively. The polymers were characterized by NMR (¹H, ¹³C, and ²⁹Si), infrared spectroscopy (IR), size-exclusion chromatography (SEC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Hydrolytic degradation studies of the polymers solvated in tetrahydrofuran and as bulk samples in the solid state were performed in the presence of atmospheric water as the nucleophilic cleavage agent, and the molecular weight loss was monitored by SEC. Poly(diisopropylsilyl terephthalate) (1a) and poly(dicyclohexylsilyl terephthalate) (1b) were found to be more stable towards nucleophilic degradation in comparison to poly(methyl-n-octadecylsilyl terephthalate) (1c) and poly(methyl-4-methylphenethylsilyl terephthalate) (1d), due to the presence of sterically bulky isopropyl or cyclohexyl groups attached to the silicon atoms. All of the polymers degraded into small molecules upon hydrolysis, with the exception that the degradation products of 1c and 1d self-condensed in the solid state to form the respective polysiloxanes. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3606–3613, 1999     

Self-repairing polymers: poly(dioxaborolane)s containing trigonal planar boron

The molecular weight of poly(dioxaborolane)s can be controlled during the polymerization reaction or through post-polymerization processing in such a manner that hydrolytic damage to these materials may be repaired, thereby regenerating the polymer.     

Synthesis of a new sulfonated monomer for poly(aryl ether)s

A new sulfonated monomer suitable for polyarylether synthesis was made. 1,1'‐(p‐Phenylenedioxy)bis[4‐(4‐fluorobenzoyl)]benzene was prepared from phosphorus pentoxide/methanesulfonic acid (PPMA), 1,4‐diphenoxybenzene, and p‐fluorobenzoic acid in good yield. This compound was selectively monosulfonated on the most activated ring with fuming sulfuric acid and isolated as the sodium salt. Poly(aryl ethers) made from this monomer may find use as proton exchange membranes. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:553–556, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20137     

Synthesis and characterization of certain new poly(bisimide)s. I

Maleic and citraconic anhydrides were reacted with several diamines to obtain a novel class of high temperature resistant bisimides.^1–3 The bisimides were characterized by melting points, elemental analysis, UV–Vis, ¹H- and ¹³C-NMR, and mass spectral analysis. The bisimide monomers were then polymerized by the addition process. A poly(amidemaleimide) was also synthesized by reacting maleic anhydride with p-aminobenzhydrazide. The thermal stability of these highly crosslinked poly(bisimide)s were examined by TGA and DTA. A neat bisimide monomer obtained from 2,2′-bis[4(p-aminophenoxy)phenyl] propane with maleic anhydride namely, 2,2′-bis[4-(p-maleimidophenoxy)phenyl]propane was reacted with 2,2′-bis[4(p-aminophenoxy)phenyl]propane by the Michael reaction.⁴ A fiber glass cloth reinforced laminate was prepared from bismaleimide and amine mixture and the mechanical properties of the test laminate evaluated.     

Synthesis and characterization of new hyperbranched poly(aryl ether oxadiazole)s

A new AB₂ monomer was synthesized for use in the preparation of a hyperbranched poly(aryl ether oxadiazole) with terminal phenol functionality. The AB₂ monomer contains two phenolic groups and a single aryl fluoride group that is activated toward nucleophilic displacement by the attached oxadiazole ring. The nucleophilic substitution of the fluoride with the phenolate groups led to the formation of an ether linkage. Subsequently, a hyperbranched poly(aryl ether oxadiazole) having approximately a 44% degree of branching, as determined by a combination of model compound studies and ¹H NMR, was obtained. The terminal phenolic groups underwent facile functionalization, furnishing hyperbranched polymers with a variety of functional chain ends. The nature of the chain‐end groups had a significant influence on the physical properties of the polymers, such as the glass‐transition temperature and their solubility. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3851–3860, 2001     

Synthesis and properties of novel soluble poly(aryl amine ketone)s as high-performance polymers

A series of poly(aryl amine ketone)s have been obtained by the condensation polymerization of different aromatic dibromides with different primary aromatic diamines via palladium-catalyzed aryl amination reaction. The structures of polymers are characterized by means of FT-IR, 1H NMR spectroscopy, and elemental analysis. The results show an agreement with the proposed structures. DSC and TG measurements show that polymers possess high glass transition temperature (Tg>170℃) and good thermal stability with high decomposition temperatures (TD>450℃). These novel polymers also exhibit good mechanical behaviors and good solubility.