Crosslinked poly(ester anhydride)s based on poly(ε‐caprolactone) and polylactide oligomers

Resorbable poly(ester anhydride) networks based on ε‐caprolactone, L ‐lactide, and D,L ‐lactide oligomers were synthesized. The ring‐opening polymerization of the monomers yielded hydroxyl telechelic oligomers, which were end‐functionalized with succinic anhydride and reacted with methacrylic anhydride to yield dimethacrylated oligomers containing anhydride bonds. The degree of substitution, determined by ¹³C NMR, was over 85% for acid functionalization and over 90% for methacrylation. The crosslinking of the oligomers was carried out thermally with dibenzoyl peroxide at 120 °C, leading to polymer networks with glass‐transition temperatures about 10 °C higher than those of the constituent oligomers. In vitro degradation tests, in a phosphate buffer solution (pH 7.0) at 37 °C, revealed a rapid degradation of the networks. Crosslinked polymers based on lactides exhibited high water absorption and complete mass loss in 4 days. In ε‐caprolactone‐based networks, the length of the constituent oligomer determined the degradation: PCL5‐AH, formed from longer poly(ε‐caprolactone) (PCL) blocks, lost only 40% of its mass in 2 weeks, whereas PCL10‐AH, composed of shorter PCL blocks, completely degraded in 2 days. The degradation of PCL10‐AH showed characteristics of surface erosion, as the dimensions of the specimens decreased steadily and, according to Fourier transform infrared, labile anhydride bonds were still present after 90% mass loss. © 2003 The Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3788–3797, 2003     

Surface grafting of polymers onto inorganic ultrafine particles: Reaction of functional polymers with acid anhydride groups introduced onto inorganic ultrafine particles

The surface grafting onto inorganic ultrafine particles, such as silica, titanium oxide, and ferrite, by the reaction of acid anhydride groups on the surfaces with functional polymers having hydroxyl and amino groups was examined. The introduction of acid anhydride groups onto inorganic ultrafine particle was achieved by the reaction of hydroxyl groups on these surfaces with 4-trimethoxysilyltetrahydrophthalic anhydride in toluene. The amount of acid anhydride groups introduced onto the surface of ultrafine silica, titanium oxide, and ferrite was determined to be 0.96, 0.47, and 0.31 mmol/g, respectively, by elemental analysis. Functional polymers having terminal hydroxyl or amino groups, such as diol-type poly(propylene glycol) (PPG), and diamine-type polydimethylsiloxane (SDA), reacted with acid anhydride groups on these ultrafine particles to give polymer-grafted ultrafine particles: PPG and SDA were considered to be grafted onto these surfaces with ester and amide bond, respectively. The percentage of grafting increased with increasing acid anhydride group content of the surface: the percentage of grafting of SDA (M_n = 3.9 × 10³) onto silica, titanium oxide, and ferrite reaching 64.7, 33.7, and 24.1%, respectively. These polymer-grafted ultrafine particles gave a stable colloidal dispersion in organic solvents.     

Esters of alternating copolymers of maleic or 2,3-dimethylmaleic anhydride with alkyl vinyl ethers

Maleic anhydride or 2,3-dimethylmaleic anhydride was copolymerized with a number of alkyl vinyl ethers, with AIBN as the initiator. The comonomers were always alternating and were obtained in yields ranging from 15 to 99%. The acid anhydride group in both series of copolymers was converted to the corresponding methyl esters in a two-step reaction. The structure of these polymers was established by elemental analysis and by infrared, ¹H-and ¹³C-NMR spectroscopy. Addtional characterization of these copolymers were carried out by viscosity measurements, differential scanning calorimetry for the determination of glass transition temperatures, and thermal degradation for the determination of the thermal stability of the copolymers.     

Synthetic analogues of polynucleotides—XIII: The resolution of dl-β-(thymin-1-yl)alanine and polymerisation of the β-(thymin-1-yl)alanines

dl-β-(Thymin-1-yl)alanine has been resolved into d(+) and l(?) forms. The pure d(+) form was obtained by fractional crystallisation of the (+)α-methylphenylethylamine salts of the α-N-formyl derivatives. The pure l(?) isomer was obtained on a small scale by chromatography of the same salts. The optically active amino acids and the dl-mixture were polymerised by the mixed anhydride procedure to give polymers which showed no evidence of base stacking or of interaction with polyadenylic acid. The molecular weights of the polymers were in the range 2–4 × 10³. These were determined by end group assay which involved the synthesis of α-N-(2,4-dinitrophenyl)-dl-β-(thymin-1-yl)alanine as a standard.     

Siloxane polymers containing azo moieties synthesized by click chemistry for photo responsive and liquid crystalline applications

Three new types of siloxane‐based photoactive liquid crystalline polymers containing azo side groups were synthesized through the click chemistry route. The polymers having molecular weight range of 14,000–34,000 g mol^?1 were soluble in most of the polar solvents like chloroform, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, and dichloromethane. The photoresponsive trans–cis photoisomerization under UV radiation and cis–trans relaxation process in dark for the polymers were studied. The isomerization rate constants were found to be 0.01–0.04 sec^?1 and 1.16*10^?4–4.67*10^?4 sec^?1, respectively. It has been noted that the polymers showed high intensity absorption for n‐π* in chloroform. Both trans and cis forms of azide monomers having azo moiety exhibited molar extinction coefficient ( ? _max) in the range of 22,000–33,000 L mol^?1 cm^?1. The thermotropic behavior of the polymers was studied by polarizing optical microscope (POM) and differential scanning calorimetry (DSC) experiments. Polymer P1 showed liquid crystalline textures of nematic droplets, whereas P2 showed smectic focal conic texture and nematic droplets. Polymer P1 was also studied for photomechanical bending on exposure to UV radiation. The polymers showed initial degradation temperature in the range of 210–275°C. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Green polymer chemistry: new methods of polymer synthesis using renewable starting materials

The present article reviews the recent results reported mainly from our group on “green polymer chemistry”. Characteristic important aspects of green polymer chemistry include herein, typically (1) using renewable resources as starting materials for polymer production, and (2) employing green method for the polymer synthesis. As renewable starting materials, the following materials were employed; lactic acid, itaconic anhydride, renewable plant oils, and cardanol. Polymer production using these materials contributes to mitigate the carbon dioxide emission because of their “carbon neutral” nature. As green method, lipase enzyme was mainly used for polymerization catalyst, since lipase is a natural benign catalyst, showing a specific catalysis as well as recyclable character. Polymer synthesis from these materials and the catalyst provided various value-added functional polymers, demonstrating good examples of green polymer chemistry.

     

Synthesis of nonlinear optical polymers with large photoconductive sensitivity and transparency

Novel nonlinear optical (NLO) chromophore, 2-{3-[2-(4-methylsulfonylphenyl)vinyl]carbazol-9-yl}ethanol was synthesized and subsequently reacted with methacryloyl chloride to give a photoconducting NLO monomer ( M1 ). 2-Methylacrylic acid 2-[3-(diphenylhydrazonomethyl)carbazol-9-yl]ethyl ester ( M2 ) was also synthesized as a comonomer to enhance the carrier mobility of the NLO polymer. Photoconducting NLO polymers, P1 and P2 were obtained by the copolymerization of Ml with methyl methacrylate and M2 , respectively. These polymers were well soluble in organic solvents and showed glass transition at 177 °C and 196 °C, respectively. Polymer films of P1 and P2 were optically clear, and were transparent at wavelengths longer than 420 nm. The electro-optic coefficient (r₃₃) of poled P1 films was measured to be ∼5 pm/V at 632.8 nm. The photoconductive sensitivities of P1 and P2 were 6.2 × 10⁻¹⁴ S·cm⁻¹/mW·cm⁻² and 5.6 × 10⁻¹¹ S·cm⁻¹/mW·cm⁻².     

Synthesis of photoreactive poly(ether ether ketone)s containing alkyl groups

Poly(ether ether ketone)s containing alkyl groups were prepared by nucleophilic substitution reaction of alkyl-substituted difluoro diaryl ethers with hydroquinone or by electrophilic substitution reaction of alkyl-substituted diaryl ether with 4,4′-oxydibenzoic acid in PPMA. Polycondensations proceeded smoothly and produced polymers having inherent viscosities up to 0.5-–1.6 dL/g. The polymers were quite soluble in strong acid, dipolar aprotic solvents, and chloroform at room temperature. Thermogravimetry of the polymers showed excellent thermal stability, indicating that 10% weight loses of the polymers were observed in the range above 450°C in nitrogen atmosphere. The glass transition temperatures of the polymers ranged from 128 to 146°C. Furthermore, Polymer 3b functioned as a photosensitive resist of negative type for UV radiation. The resist had a sensitivity of 42 mJ/cm² and a contrast of 2.5, when it was postbaked at 100°C for 10 min, followed by development with THF/acetone at room temperature. © 1996 John Wiley & Sons, Inc.     

Polynucleotide analogues. VI. Synthesis and characterization of alternating copolymers of maleic anhydride and dihydropyran containing guanine derivatives

2-Amino-6-chloropurine was reacted with 2-(tosyloxymethyl)-2,3-dihydro-2H-pyran to give 2-(2-amino-6-chloropurin-9-ylmethyl)-2,3-dihydro-2H-pyran ( 3 ) and its N⁷-isomer ( 4 ), which were treated with 5% aqueous trimethylamine to result in 2-(guanin-9-ylmethyl)-2,3-dihydro-2H-pyran ( 5 ) and its N⁷-isomer ( 6 ), respectively. 2-(N²-Acetylguanin-9-yl-methyl)-3,4-dihydro-2H-pyran ( 7 ) and 2-(N²-acetylguanin-7-ylmethyl)-3,4-dihydro-2H-pyran ( 8 ), obtained by acetylation of compounds 5 and 6 , were copolymerized with maleic anhydride to give the alternating copolymers 9 and 10 , and they were hydrolyzed to result in poly[ {2-(guanin-9-ylmethyl)tetrahydropyran-5,6-diyl} {1,2-dicarboxyethylene}] ( 11 ) and poly[ {2-(guanin-7-ylmethyl)tetrahydropyran-5,6-diyl} {1,2-dicarboxyethylene}] ( 12 ), re-spectively. Polymer 11 showed hypochromicity whereas 12 exhibited hyperchromicity in aqueous solutions. Polymers 11 and 12 in aqueous solutions showed very strong excimer fluorescence with the maximum intensities at 432 and 446 nm, respectively, at room tem-perature. The two polymers showed polyelectrolyte effects, e.g., very high GPC molecular weights as well as reduced viscosities at low concentrations in water. Normal behavior was retained by addition of inorganic salts. Sodium salts of polymers 11 and 12 migrated to the anode by electrophoresis and both showed two bands. © 1995 John Wiley & Sons, Inc.     

Novel amine-containing biodegradable polyester via copolymerization of aspartic anhydride and 1,4-cyclohexanedimethanol

A novel biodegradable polyester having pendant amine functional groups was snythesized from N-(benzyloxycarbonyl)-L -aspartic anhydride ( 2 ) and 1,4-cyclohexanedimethanol ( 3 ) by polycondensation reaction using p-toluenesulfonic acid as a catalyst. The synthesized polymer 4 shows the characteristic ester carbonyl absorption peak at 1732 cm⁻¹ in the IR spectrum, and the NMR spectra were consistent with the IR data. Also, the elemental analysis showed that the experimental and calculated values were very close to each other. The weight-average molecular weight of the polymers ranged from 1140 to 5050 and increased with increasing reaction time. This new polymer would have the potential of a drug delivery biomaterial.     

Synthesis,structure, cytotoxic activities,and DNA-binding of 1-D copper(II) and zinc(II) coordination polymers

Two 1-D coordination polymers have been synthesized and identified as [Zn(ox)(en)] _n (H₂O)_{2 n} (1) and [Cu₂(dmeo)(N₃)₂] _n (2), where en represents diaminoethane, ox and dmeo stand for dianions of oxalic acid and N,N′-bis[2-(dimethylamino)ethyl]oxamide, respectively. Polymer 1 was characterized by elemental analysis, molar conductance measurement, IR and electronic spectra, and single-crystal X-ray diffraction. Polymer 1 consists of 1-D chains bridged by oxalate. The Zn^II can be described as a distorted octahedral environment and the Zn^II···Zn^II separation through the μ-oxalato-bridge is 5.5420(9)?Å. Hydrogen bonds assemble the coordination polymers to a 3-D supermolecular structure. The crystal structure of 2 has been reported previously. However, the bioactivities were not studied. The DNA-binding properties and cytotoxic activities of the two coordination polymers are investigated. The results suggest that the two polymers interact with HS-DNA in groove binding with binding affinity following the order of 1?>?2, which is consistent with their anticancer activities.     

15N-NMR spectroscopy 32. Synthesis and characterization of polyelectrolytes based on polyaminamides

The titrations of the polyammamides prepared from adipic acid and diethylenetriamine or di(3-aminopropyl)methylamine were monitored by means of natural-abundance ¹⁵N-(NMR) nuclear magnetic resonance spectra. Opposite shift effects were found for amine and amide nitrogens upon protonation of the amino groups. These shift effects allow one to distinguish substitutions involving exchange of electric charges from other substitutions without isolation of the polymers. Reactions of the polyaminamides with β-propiolactone, γ-butyroslution, methyl-methane sulfonate, prolyleneoxide, epichlorohydrine, maleic acid anhydride, succinic acid anhydride, carbon dioxide, ethylchloroformate, and methyne sulfonylchloride were carried out in water, and the resulting polyelectrolytes were characterized by means of ¹⁵N-NMR spectra.     

Head-to-head vinyl polymers. XI. Preparation and characterization of poly(methyl acrylate) and poly(methyl methacrylate) consisting of head-to-head and head-to-tail units through cyclopolymerization of acrylic and methacrylic anhydrides

Acrylic anhydride (AAn) and methacrylic anhydride (MAAn) were polymerized with radical initiator in polar solvents at high temperatures. The polymers obtained were found to consist of five-and six-membered ring structures by comparing IR spectra of the polymers with those of model compounds, succinic anhydride, and glutaric anhydride. Hydrolysis and methylation of the polymers gave new polymers composed of head-to-head (HH) and head-to-tail (HT) methyl acrylate (MA) or methyl methacrylate (MMA) units. The content of HH unit of these HH/HT polymers was determined by ¹H-NMR and ¹³C-NMR spectra. The softening, glass transition, and thermal degradation temperatures of the poly(MA) with HH and HT units were found to somewhat increase with increasing of the content of the HH units. On the other hand, the glass transition and thermal degradation temperatures of the poly(MMA) with HH and HT units increased similarly, but the softening temperature decreased as the content of the HH units increased.     

Soluble dithienothiophene polymers: Effect of link pattern

Soluble conjugated polymers based on 3,5‐didecanyldithieno[3,2‐b:2′,3′‐d]thiophene—single‐bond ( 1 ), double‐bond ( 2 ), and triple‐bond linked ( 3 )—were synthesized by palladium(0)‐catalyzed Stille coupling reaction and oxidation polymerization. The thermal, absorption, emission, and electrochemical properties of these polymers were examined; the effect of the link pattern was studied. All polymers exhibit decomposition temperatures over 295 °C and glass‐transition temperatures in the range of 137–202 °C. The absorption spectra of 1 , 2 , and 3 in thin films exhibit absorption maxima at 381, 584, and 444 nm, respectively. Polymer 1 exhibits intense green emission located at 510 nm in film, whereas polymers 2 and 3 are nonemissive both in solution and in film due to H‐aggregate. Cyclic voltammograms of polymers 1 , 2 , and 3 display irreversible oxidation waves with onset oxidation potentials at 1.73, 0.78, and 1.03 V versus Ag⁺/Ag, respectively. Theory calculation on model compounds suggests that the dihedral angle decreases in the order of 1 > 3 > 2 . On reducing the dihedral angle, the polymer exhibits a longer absorption maximum, a smaller bandgap, a less oxidizing potential and fluorescence quench, due to more coplanar and more π‐electron delocalized backbone structure. Polymer solar cells were fabricated based on the blend of polymer 2 and methanofullerene [6,6]‐phenyl C61‐butyric acid methyl ester (PCBM). The power conversion efficiency of 0.45% was achieved under AM 1.5, 100 mW cm^?2 using polymer 2 :PCBM (1:2, w/w) as active layer. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2843–2852, 2009     

Polycondensations of hydroxycarboxylic acids derived from optically active aminoalcohols and acid anhydrides—syntheses of functional poly(ester-amide)s

Syntheses and polycondensations of optically active hydroxycarboxylic acids prepared from acid anhydrides and aminoalcohols were carried out. Novel polymers with M̄_n 9900–27,200 were obtained by the polycondensations of hydroxycaboxylic acids derived from maleic or succinic acid using 1.2 eq. of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC · HCl) in DMF (2M) at room temperature for 8 h in satisfactory yields. Meanwhile, a hydroxycarboxylic acid obtained from phthalic acid afforded no polymer but a phthalimide derivative. The radical additions of ethanethiol or mercaptoethanol with the polymers derived from maleic anhydride proceeded smoothly in satisfactory incorporation ratios (65–98%), respectively. The polymer obtained from succinic anhydride and 2-aminoethanol showed hydrolytic degradability. © 1997 John Wiley & Sons, Inc.     

Thermally stable polymers from 1,4,5,8-naphthalenetetracarboxylic acid and aromatic tetraamines

Polycondensations of 1,4,5,8-naphthalenetetracarboxylic acid (NTCA) with both 3,3′-diaminobenzidine (DAB) and 1,2,4,5-tetraaminobenzene tetrahydrochloride (TAB) in polyphosphoric acid (PPA) were found to produce soluble polymers which exhibit excellent thermal stabilities. Polymer structures were deduced from infrared, thermal, and elemental analyses of model compounds and polymers. Polymer derived from TAB had a ladder-type structure. Polymers with solution viscosities near 1 or above (determined in H₂SO₄) were obtained from polymerizations near 200°C., and analysis showed these to possess a very high degree of completely cyclized benzimidazobenzophenanthroline structure. Less vigorous reaction conditions gave polymers with lower solution viscosities which appeared to be less highly cyclized. Low-viscosity polymer was also prepared from DAB and NTCA by solid-phase polycondensation. Some advancements in the solution viscosities of polymers synthesized from DAB in PPA were caused by second staging in the solid phase.     

Synthesis,spectral, and antibacterial screening studies of chelating polymers of bisphenol-A–formaldehyde resin bearing barbituric acid

A new polymeric ligand was synthesized by the reaction of bisphenol-A and formaldehyde in the basic medium, followed by condensation polymerization with barbituric acid in the acidic medium. Polymer metal complexes were prepared by reaction of this resin with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II). The polymeric resin and its metal polychelates were characterized by elemental analysis, FT-IR, ¹³C-NMR, and ¹H-NMR spectra. The geometry of the polymer metal complexes was evaluated by electronic spectra (UV-Vis) and magnetic moment measurement. Thermal stabilities show an increased thermal stability of the metal polychelates compared to the ligand. The antibacterial activities of all the synthesized polymers were investigated against Bacillus subtilis, Staphylococcus aureus, and Escherichia coli, showing good antibacterial activities against these bacteria. Cu(II) polychelate showed highest biocidal activity.     

Novel optically active poly(amide-imide)s derived from L-aspartic acid

2,6-Bis-(2,5-dioxo-tetrahydro-N-(4-carboxyphenyl)pyrrol-3-yl)-pyrrolo[3,4-f]isoindole-1,3,5,7-teraone, a chiral diacid, was prepared from pyromellitic anhydride and L-aspartic acid in a three steps reaction pathway. The polycondensation reactions of the monomer with aromatic diamines were carried out in direct condensation reaction conditions. The synthesized poly(amide-imide)s had inherent viscosities in the range of 0.30–0.80 dl/g. Identification of all of the products were performed by conventional analytical techniques such as TLC, IR and ¹H NMR/¹³C MR spectroscopy. Thermoanalytical techniques (TGA/DSC) showed useful levels of thermal stability, associated with relatively high glass transition temperatures and carbonized residues in excess of 40% at 600°C for the synthesized polymers. Amorphous morphology was obtained based on XRD patterns and DSC traces. The polymers were soluble in a variety of polar organic solvents and afforded transparent and relatively flexible to brittle films by solution casting.     

Thermally stable polymers based on bismaleimides containing amide,imide, and ester linkages

Seven new structurally different bismaleimides were synthesized and characterized by infrared and proton nuclear magnetic resonance spectroscopy. The chain of these polymer precursors was extended by incorporating amidized, imidized, and esterified 4-chloroformyl phthalic anhydride. The bismaleimides containing amide and imide linkages were prepared by a simple synthetic route based on the reaction of the monomaleamic acid derived from various aromatic diamines (1 mol) with 4-chloroformyl phthalic anhydride (0.5 mol) and subsequent cyclodehydration of the intermediate triamic acid. In addition, chain extended bismaleimides were prepared by reacting the monomaleamic acid derived from p-phenylenediamine with several dianhydrides such as p-phenylene bis(trimellitamide anhydride), p-phenylene bis(trimellitate anhydride), and bis-phenol A bis(trimellitate anhydride). The differential thermal analysis scans of bismaleimides showed exotherms at 221–304°C associated with their polymerization reactions. The thermogravimetric analysis traces of polymers did not show a weight loss up to 351–393 and 344–372°C in N₂ and air atmospheres, respectively. The anaerobic char yield of polymers at 800°C was 44–61%. These polymers can be used for fabrication of composites having improved properties.     

Substituent effect on azobenzene‐based liquid‐crystalline organophosphorus polymers

An Erratum has been published for this article in Journal of Polymer Science Part A: Polymer Chemistry (2003) 41(23) 3862 A new series of combined‐type, azobenzene‐based organophosphorus liquid‐crystalline polymers were synthesized, and their photoisomerization properties were studied. The prepared polymers contained azobenzene units as both the main‐chain and side‐chain mesogens. Various groups were substituted in the terminal of the side‐chain azobenzene mesogen, and the effects of the substituents were investigated. All the polymers were prepared at the ambient temperature by solution polycondensation with various 4‐substituted phenylazo‐4′‐phenyloxyhexylphosphorodichloridates and 4,4′‐bis(6‐hydroxyhexyloxy) azobenzene. The polymers were characterized with gel permeation chromatography, Fourier transform infrared, and ¹H, ¹³C, and ³¹P NMR spectroscopy. Thermogravimetric analysis revealed that all the polymers had high char yields. The liquid‐crystalline behavior of the polymers was examined with hot‐stage optical polarizing microscopy, and all the polymers showed liquid‐crystalline properties. The formation of a mesophase was confirmed by differential scanning calorimetry (DSC). The DSC data suggested that mesophase stability was better for electron‐withdrawing substituents than for halogens and unsubstituted ones. Ultraviolet irradiation studies indicated that the time taken for the completion of photoisomerization depended on the dipolar moment, size, and donor–acceptor characteristics of the terminal substituents. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3188–3196, 2003