Synthesis and characterization of poly(ester-urethane-imide)s by Diels–Alder polyaddition

Poly(ester-urethane-imide)s were prepared by Diels–Alder polyaddition of 1,6-hexamethylene-bis(2-furanylmethylcarbamate) with various bismaleimides containing ester groups in the backbone. The Diels–Alder reaction was carried out in m-cresol, at 110°C, followed by thermal and chemical aromatization of tetrahydrophthalimide intermediates. The monomers and polymers were characterized by IR, ¹H-NMR spectroscopy and elemental analysis. Thermal properties of the polymers were investigated by differential scanning calorimetry and dynamic thermogravimetric analysis.     

Synthesis and characterization of a novel amphiphilic poly (ethylene glycol)–poly (ε-caprolactone) graft copolymers

A series of amphiphilic graft copolymers PEO-g-PCL with different poly (ε-caprolactone) (PCL) molecular weight were successfully synthesized by a combination of anionic ring-opening polymerization (AROP) and coordination-insertion ring-opening polymerization. The linear PEO was produced by AROP of ethylene oxide (EO) and ethoxyethyl glycidyl ether initiated by 2-(2-methoxyethoxy) ethoxide potassium, and the hydroxyl groups on the backbone were deprotected after hydrolysis. The ring-opening polymerization of CL was initiated using the linear poly (ethylene oxide) (PEO) with hydroxyl group on repeated monomer as macroinitiator and Sn(Oct)₂ as catalyst, then amphiphilic graft copolymers PEO-g-PCL were obtained. By changing the ratio of monomer and macroinitiator, a series of PEO-g-PCL with well-defined structure, molecular weight control, and narrow molecular weight distribution were prepared. The expected intermediates and final products were confirmed by ¹H NMR and GPC analyzes. In addition, these amphiphilic graft copolymers could form spherical aggregates in aqueous solution by self-assemble, which were characterized by transmission electron microscopy, and the critical micelle concentration values of graft copolymers PEO-g-PCL were also examined in this article.     

Synthesis and characterization of poly(N-acryloyl’-methyl piperazinium(+1)) tetrachlorometallate (II) compounds

Summary The interactions of metal ions with poly(N-acryloyl N-methyl piperazine) in the solid state were studied. The Cu(II) and Zn(II) compounds were prepared and characterized by means of elemental analysis; FT-IR, electronic spectroscopies, and thermogravimetric analysis. PM3 semiempirical calculations on the polymer conformations and the Zn(II) complex have been performed. The piperazine group in the polymer shows the conformations; namely; the chair and a distorted chair conformation. Both structures differ by just ca. 10 kcal/mol. In the compounds MCl₄(PAPH)₂ the MCl₄ ^2- complex ion presents a distorted tetrahedral geometry. The electronic spectrum of the yellow Cu(II) coordination compound shows a band at 894 nm. In the IR spectra, an absorption band at 3020 cm^-1 has been assigned to the v(N-H) stretching mode of the NH⁺ group. The protonated nitrogen atom is the one bonded to the methyl group due to the larger basicity according to the calculated electronic charge density and to the lower steric hindrance. The interaction of the MCl₄ ^2- anion and the polymer is achieved by hydrogen bonding at the NH⁺ group and the chloride with N-H ···Cl distances lying betwen 1.7 to 3.3 A°.     

Synthesis and characterization of polymers from β-propiolactone and poly(ethylene glycol)s

Uncatalysed polymerizations of β-propiolactone with low-molecular-weight poly(ethylene glycol)s were carried out in bulk, at temperatures in the range of 70 to 120°C. ¹H nuclear magnetic resonance (n.m.r.) and differential scanning calorimetry (d.s.c.) measurements on the resulting products indicated a block copolymer structure. Gel permeation chromatography (g.p.c.) and d.s.c. analyses showed that in some cases the copolymerization is accompanied by homopolymerization of β-propiolactone, probably due to the presence of residual water in the poly(ethylene glycol). N.m.r. and infra-red (i.r.) spectra of copolymers revealed the presence of hydroxyl and carboxyl end groups. The copolymerization reaction may be visualized as a two-step process, in which the ring opening of β-propiolactone takes place on both the hydroxyl groups of poly(ethylene glycol), followed by repetitive monomer addition forming an ester-ether-ester triblock copolymer.     

Synthesis and characterization of polyrotaxanes comprising α-cyclodextrins and poly(ε-caprolactone) end-capped with poly(N-isopropylacrylamide)s

Biodegradable polyrotaxane (PR)-based triblock copolymers were synthesized via the atom transfer radical polymerization (ATRP) of N-isopropylacrylamide (NIPAAm) initiated with polypseudorotaxanes (PPRs) consisting of a distal 2-bromopropiomyl bromide end-capping poly(ε-caprolactone) (Br-PCL-Br) and a varying amount of α-cyclodextrins (α-CDs) in the presence of Cu(I)Br/PMDETA at 25 °C in aqueous solution. The copolymers were featured by relatively higher yields from 46.0% to 82.8% as compared with previous reports. Their structure was characterized in detail by using ¹H NMR, ¹³C CP/MAS NMR, GPC, WXRD, DSC and TGA analyses. When a feed molar ratio of NIPAAm to Br-PCL-Br was changed from 50 to 200, the degree of polymerization of PNIPAAm blocks attached to two ends of PPRs was in a range of 158–500. About one third of the added α-CDs were still entrapped on the central PCL chain after the ATRP process. Attaching PNIPAAm rendered the copolymers soluble in aqueous solution showing the thermo-responsibility as evidenced by turbidity measurements.     

Synthesis and properties of hybrid alkyd–acrylic dispersions and their use in VOC-free waterborne coatings

Hybrid waterborne alkyd–acrylic dispersions with solid content of 40%, free from any surfactant and exempt of any organic solvent, were successfully synthesized by a melt co-condensation reaction between an acrylic prepolymer bearing carboxylic groups and a long-oil alkyd resin. Spontaneous emulsification of the ensuing hybrid resin was achieved by the addition of an aqueous ammonia solution that neutralized the carboxylic functions. The key role of the carboxylic groups on the stabilization process and on the storage stability of the dispersion was assessed and it was shown that the insertion of anhydride moieties within the acrylic prepolymer ensured the efficient coupling between the acrylic and the alkyd resin and prevented the phase separation. These dispersions are easy to implement and might be used to prepare high quality zero VOC coatings in terms of drying time, stability and gloss. The most stable dispersion was also used in the formulation of air-drying waterborne lacquers and their coating properties were evaluated.     

Synthesis and characterization of aromatic polyamides derived from various derivatives of 4,4’-oxydianiline

Three aromatic diamines, 2,2′-diiodo-4,4′-oxydianiline (DI-ODA 2), 2,2′-bis[p-(trifluoromethyl)phenyl]-4,4′-oxydianiline (BTFP-ODA 3) and 2,8-diaminodibenzofuran (DADBF 5) were synthesized by using 4,4-oxydianiline (4,4′-ODA) as the starting material. New aromatic polyamides 6, 7 and 8 were prepared from these three diamines and six commercially available aromatic diacids by direct polycondensation, respectively. Polyamides 6 and 7 contained bulky iodide and p-trifluoromethylphenyl substitutents that would hinder the chain packing and increase the free volume. They exhibited good optical transparency in visible light region and showed excellent solubility in organic solvents such as DMSO, DMAc, DMF and NMP. Polyamides 8 containing planar dibenzofuran moieties had the highest glass transition temperatures and decomposition temperatures among these polyamides. Polyamides 6 had the lowest decomposition temperatures due to the presence of weak carbon–iodine bond. All of these polyamides showed amorphous nature evidenced by wide angle X-ray diffraction. No endothermic peaks were observed from DSC thermograms up to their decomposition temperatures. High optical transparency and excellent solubility combined with good thermal stability make these polyamides attractive for potential soft electronics applications.     

Synthesis and characterization of new poly(ether–ester–imide)s as a generation of soluble and thermally stable polymers

A new-type of dicarboxylic acid 6 was synthesized from the reaction of 1,4-bis[4-aminophenoxy]butane 4 with trimellitic anhydride 5 in a solution of glacial acetic acid/pyridine (Py) at refluxing temperature. 1,4-Bis[4-nitrophenoxy]butane 3 was prepared by reaction of 4-nitrophenol 1 with 1,4-dibromo butane 2 in N,N-dimethylformamide (DMF) solution. Then dinitro 3 was reduced to 1,4-bis[4-aminophenoxy]butane 4 by using 10% Pd–C, ethanol, and hydrazine monohydrate. So six new thermally stable and organosoluble poly(ether–ester–imide)s (PEEIs) 8a–f with good inherent viscosities were synthesized by the direct polycondensation reaction of new 1,4-bis[4-(trimellitimido)phenoxy]butane 6 with several aromatic diols 7a–f through direct polycondensation using tosyl chloride (TsCl)/pyridine (Py)/DMF system as condensing agent. The resulted polymers were fully characterized by means of FTIR and ¹H NMR spectroscopy, elemental analyses, inherent viscosity, solubility tests, differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), and derivative of thermogravimetric (DTG).     

Synthesis and characterization of poly(ethyl vinyl ether) containing the NLO-phore 4′-oxy-4-nitrostilbene in the side chain

Summary 4-(2-Vinyloxyethoxy)-4-nitrostilbene 2 was prepared by the reaction of 4-hydroxy-4-nitrostilbene 1 with 2-iodoethyl vinyl ether. Monomer 2 was polymerized with cationic initiators to obtain a poly(ethyl vinyl ether) with the NLO-phore 4-oxy-4-nitrostilbene in the side chain. The resulting polymer 3 was soluble in common solvents such as chloroform and DMSO. The inherent viscosities of polymer 3 were in the range of 0.25–0.30 dL/g in chloroform. Polymer 3 showed a good thermal stability in TGA thermogram. Solution-cast films were cloudy and brittle with a T_g of 63°C.     

Synthesis and characterisation of silica–carbon nanotube hybrid microparticles and their effect on the electrical properties of poly(vinyl alcohol) composites

Hybrid silica–carbon nanotube (CNT) particles with a radial symmetry were produced by the growth of nanotubes onto spherical, mesoporous silica gel particles using the floating catalyst chemical vapour deposition (FC-CVD) method. Characterisation of the hybrid particles, using electron microscopy, Raman spectroscopy and thermogravimetry showed the geometry and porosity of the silica particles to influence the alignment and density of the CNTs produced. CNT growth initiated in the pores of the gel particles and three hours of CVD growth were required to get extensive surface coverage. In the early stages of growth, the reactants diffused inside the mesoporous silica and consequently the CNTs grew mainly within the silica gel rather than on the surface. Some indication of catalyst templating was observed within the smaller (<10 nm) pores, but this templating did not result in aligned CNTs. Composite films of hybrid silica–CNT particles in poly(vinyl alcohol) were cast and their impedance measured. An electrical percolation threshold of 0.62 wt.% was found for the hybrid particles, of which 0.20 wt.% were CNTs.     

Synthesis,characterization, and drug release properties of poly(N-isopropylacrylamide) gels prepared in methanol–water cononsolvent medium

Poly(N-isopropylacrylamide) (PNIPAM) hydrogels were simply prepared by free radical polymerization in different methanol–water mixture. A scanning electron microscopy study revealed that the freeze-dried hydrogels were macroporous. The swelling ratios in water at 20°C of the resulting hydrogels followed the order: X_0.43>X_0.21>X_0.76 ≈ X_0.57>X_0.31>X_0.13>X_0.06>X₀, where X_m denotes a gel prepared in a methanol–water mixture with m mole fraction of methanol (x_m). Below the lower critical solution temperature, the swelling ratio values of all of the hydrogels gradually decreased with the increase in the temperature. The complete collapse of the PNIPAM chain of all the gels occurred at about 38°C, whereas the same was observed at about 35°C for the conventional gel prepared in water. The swelling ratio values of all the PNIPAM gels in the methanol–water mixtures with different x_m values at 20°C passed through a minimum in the cononsolvency zone. The deswelling rates of the hydrogels decreased in the following order: X_0.43> X_0.31> X_0.21> X_0.57> X_0.76 ≈ X_0.13> X_0.06> X₀. The reswelling rates of these hydrogels decreased in the following order: X₀> X_0.31> X_0.06 ≈ X_0.13 > X_0.76> X_0.57> X_0.21> X_0.43. The release rates of the Tramadol Hydrochloride drug at 37°C from the drug-loaded hydrogels were almost same for all of the hydrogels. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of novel polyimides derived from 4,4’-bis(5-amino-2-pyridinoxy)benzophenone: effect of pyridine and ketone units in the main

A diamine monomer, 4,4’-bis(5-amino-2-pyridinoxy)benzophenone, was designed and synthesized, and used to react with commercially different kinds of aromatic dianhydrides to prepare a series of polyimides containing pyridine and ketone units via the classical two-step procedure. Glass transition temperatures (T_g) of the resultant polyimides PI-(1–5) derived from 4,4’-bis(5-amino-2-pyridinoxy) benzophenone with various dianhydrides ranged from 201 to 310 °C measured by differential scanning calorimetry. The temperatures for 5%wt loss of the resultant polyimides in nitrogen atmosphere obtained from the thermogravimetric analysis curves fell in the range of 472–501 °C. The temperatures for 10%wt loss of the resultant polyimides in nitrogen atmosphere fell in the range of 491–537 °C. Meanwhile, the char yields at 800 °C were in the range of 55.3–60.8%. Moreover, the moisture absorption of polyimide films was measured in the range of 0.37–2.09%. The thin films showed outstanding mechanical properties with tensile strengths of 103–145 MPa, an elongation at break of 12.9–15.2%, and a tensile modulus of 1.20–1.88 Gpa, respectively. The coefficients of thermal expansion of the resultant polyimides were obtained among 26–62 ppm °C^?1. To sum up, this series of polyimides had a good combination of properties applied for high-performance materials and showed promising potential applications in the fields of optoelectronic devices.     

Synthesis and characterization of (poly (N-vinyl formamide)—pregelled starch—graft copolymer

Bromate / cyclohexanone redox system was investigated as a novel initiator for graft copolymerization of N-vinyl formamide onto pregelled starch. A number of variables in the grafting reaction were investigated including N-vinyl formamide, cyclohexanone, bromate ion, sulphuric acid and pregelled starch concentrations, material to liquor ratio along with polymerization time and temperature. The graft copolymers were evaluated in terms of graft yield, graft reaction efficiency and homopolymer formation (%). The optimum conditions for grafting of N-vinyl formamide onto pregelled starch are: N-vinyl formamide 50% based on weight of substrate, cyclohexanone 15 mmol / l, bromate ion, 30 mmol / l, liquor ratio 10, pH 6, time 120 min., and temperature 40°C. On the other hand, characterizations of the resultant copolymers with respect to swelling capacity, solubility %, metal ion up-take and suitability as a sizing agent for cotton textiles were investigated. The results obtained reflect that, the resultant copolymer shows better results for the aforementioned properties in comparison with that obtained from native pregelled starch as a starting substrate.     

Modified poly(ether–imide–amide)s with pendent benzazole structures: Synthesis and characterization

Three series of novel modified poly(ether–imide–amide)s (PEIAs) having pendent benzazole units were prepared from diimide–dicarboxylic acids, including 2-[3,5-bis(4-trimellitimidophenoxy) phenyl]benzimidazole, 2-[3,5-bis(4-trimellitimidophenoxy) phenyl]benzoxazole, and 2-[3,5-bis(4-trimellitimidophenoxy) phenyl]benzothiazole, with various diamines by direct polycondensation in N-methyl-2-pyrrolidone with triphenyl phosphite and pyridine as condensing agents. These new diimide–dicarboxylic acids containing ether linkages and benzazole pendent groups were synthesized by the condensation reaction of 5-(2-benzimidazole)-1,3-bis(4-aminophenoxy)benzene, 5-(2-benzoxazole)-1,3-bis(4-aminophenoxy)benzene, or 5-(2-benzothiazole)-1,3-bis(4-aminophenoxy)benzene with trimellitic anhydride, respectively. All of the polymers were obtained in quantitative yields with inherent viscosities of 0.39–0.65 dL/g. For comparative purposes, the corresponding unsubstituted PEIAs were also prepared by the reaction of a diimide–dicarboxylic acid monomer lacking benzazole pendent groups, namely, 3,5-bis(4-trimellitimidophenoxy) phenyl, with the same diamines under similar conditions. The solubilities of the modified PEIAs in common organic solvents and their thermal stability were enhanced compared to those of the corresponding unmodified PEIAs. The glass-transition temperature, 10% weight loss temperature, and char yields at 800°C were 19–31°C, 22–57°C and 4–8% higher, respectively, than those of the unmodified polymers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Intercalative redox polymerization and characterization of poly(4-vinylpyridine)–vermiculite nanocomposite

A new nanocomposite material consisting of poly(4-vinylpyridine) (PVP) and vermiculite is synthesized by the intercalative redox polymerization of VP in the gallery of copper(II) ion-exchanged vermiculite. The formation of a single filament of the polymer in the gallery is confirmed by the increase in gallery spacing of 4.7 Å as indicated by X-ray diffraction (XRD) analysis. Electron spin resonance studies confirm the presence of Cu(II) upon ion exchange and its absence following redox polymerization. The amount of polymer present in the gallery is found to be ∼18–19 mass % by thermogravimetric analysis. Confining the polymer to the gallery spacing in vermiculite results in enhanced thermal stability that is evident from the increase in the initial decomposition temperature by ∼300°C. Differential scanning calorimetry of the nanocomposite indicates that the polymer is confined to a restricted geometry because of the absence of a glass-transition temperature, which confirms the XRD finding. The IR absorption peaks corresponding to PVP and the expected PVP UV π–π* transition at 275 nm, along with the XRD and thermal data confirms that the gallery expansion is due to the PVP filament. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 555–561, 2001     

Synthesis of α-hydroxy-ω-amino poly(ethylene oxide) and its use in reaction injection moulding (RIM)

Summary Computer simulations show that oligomers with two different terminal groups with dissimilar reactivities for isocyanates give a delayed viscosity rise in polyurethanes. This is a desired behaviour for RIM processes. Therefore, an -hydroxy--amino poly(ethylene oxide) (HAPEO) has been prepared. The synthesis was carried out by the ethoxylation of 2-hydroxyethyl phthalimide as a blocked amine. Hydrazinolysis appears to be the best way to obtain the deblocked oligomer. The product properties were compared with an oligomeric diamine ether (Jeffamine D2000). The gel time of HAPEO (M_n=500) and JAD2000 (M_n=2000) was the same (2 sec.). The product with HAPEO had a higher modulus, a comparable impact and tensile strength and a lower elongation at break.     

Synthesis, characterization, microstructure determination and thermal studies of poly(N-vinyl-2-pyrrolidone–maleic anhydride–styrene) terpolymer

A series of poly(N-vinyl-2-pyrrolidone–maleic anhydride–styrene) terpolymers have been synthesized using titanium(III)-dimethylglyoxime redox initiator system. The usage of redox initiators in the terpolymerization was limited; hence it should be considered as a new approach. The reactivity of the monomers has been studied by well-accepted Kelen-Tudos and Fineman-Ross linear methods and compared with the nonlinear RREVM method. The results also suggested that the RREVM method is the most reliable and superior method for the estimation of reactivity ratios. The reactivity ratios for the terpolymer (r ₁ 0.99 and r ₂ 0.05) obtained from the RREVM method showed that the N-vinyl pyrrolidone-maleic anhydride complex was more predominant than styrene in the terpolymer and the complex had more attraction toward itself than styrene. The microstructure determination study depicts that alternating polymer can be prepared by increasing the styrene feed content. The resonance factor and polarity of the complex were calculated as 5.01 and 0.93, respectively, which were different from those of the individual monomers. These calculations would help in predicting the association of monomers during copolymerization. It was observed that the glass transition temperature of the terpolymer increased as the complex ratio in the terpolymer increased. The terpolymer was thermally stable up to 323 °C.     

Oxidative degradation of poly (vinyl acetate) and poly (ε-caprolactone) and their mixtures in solution

The oxidative degradation of the poly (ε-caprolactone) (PCL), poly (vinyl acetate) (PVAC) and their mixtures in dichlorobenzene has been investigated at various temperatures (70-130°C) in the presence of benzoyl peroxide. The interaction between the polymers is quantified by monitoring the molecular weights of individual polymers using gel-permeation chromatography. The various physical mixtures employed in the present investigation are , and wt%/wt% PCL/PVAC. Experimental data indicated that the degradation is random without cross-linking and repolymerization. An optimum in degradation temperature (corresponding to maximum degradation rate) of 105°C was observed for the entire range of polymer compositions (0-100% PCL) investigated. This optimum temperature of degradation is characteristic mostly of the initiator and only to a small extent of the degrading polymer system. The experimental results of the mixtures indicated that the degradation rates of PVAC are significantly enhanced, while the degradation rates of PCL are decreased in the physical mixture. This can be attributed to the proton-accepting and proton-donating nature of PCL and PVAC, respectively. A radical mechanism for the oxidative degradation of pure polymers and their mixtures has been proposed and a model based on continuous distribution kinetics was developed considering the interaction of the polymers through hydrogen abstraction and the parameters were evaluated numerically. The activation energies for the peroxide attack for the PCL and PVAC are 10.5 and , respectively. The activation energies for the random chain scission of PCL and PVAC are 10.6 and , respectively.     

Synthesis and characterization of multiblock semi-crystalline hydrophobic poly(ether ether ketone)–hydrophilic disulfonated poly(arylene ether sulfone) copolymers for proton exchange membranes

Multiblock copolymers based on alternating segments of telechelic phenoxide terminated hydrophilic fully disulfonated poly(arylene ether sulfone) (BPS100) and decafluorobiphenyl (DFBP) terminated hydrophobic poly(arylene ether ketimine) (PEEKt), were synthesized from the hydrophilic and ketimine-protected amorphous hydrophobic telechelic oligomers by nucleophilic coupling reactions. After film formation from DMSO, the copolymer was acidified, which converted the ketimine to semi-crystalline ketone segments and the sulfonate salts to disulfonic acids. A semi-crystalline phase with a T_m of 325 °C was confirmed. The semi-crystalline multiblock copolymer membranes were tough, ductile and solvent resistant. Fundamental properties as proton exchange membranes (PEMs) showed enhanced conductivities under fully hydrated and reduced humidity conditions. These multiblock copolymers exhibited low in-plane anisotropic swelling behavior, in contrast to the random copolymers.     

Synthesis of well-defined bisbenzoin end-functionalized poly(ε-caprolactone) macrophotoinitiator by combination of ROP and click chemistry and its use in the synthesis of star copolymers by photoinduced free radical promoted cationic polymerization

A new well-defined bisbenzoin group end-functionalized poly(ε-caprolactone) macrophotoinitiator (PCL-(PI)₂) was synthesized by combination of ring opening polymerization (ROP) and click chemistry. The ROP of ε-CL monomer in bulk at 110 °C, by means of a hydroxyl functional initiator namely, 3-cyclohexene-1-methanol in conjunction with stannous-2-ethylhexanoate, (Sn(Oct)₂), yielded a well-defined PCL with a cyclohexene end-chain group (PCL-CH). The bromination and subsequent azidation of the cyclohexene end-chain group gave bisazido functionalized poly(ε-caprolactone) (PCL-(N₃)₂). Separately, an acetylene functionalized benzoin photoinitiator (PI-alkyne) was synthesized by using benzoin and propargyl bromide. Then the click reaction between PCL-(N₃)₂ and PI-alkyne was performed by Cu(I) catalysis. The spectroscopic studies revealed that poly(ε-caprolactone) with bisbenzoin photoactive functional group at the chain end (PCL-(PI)₂) with controlled chain length and low-polydispersity was obtained. This PCL-(PI)₂ macrophotoinitiator was used as a precursor in photoinduced free radical promoted cationic polymerization to synthesize an AB₂-type miktoarm star copolymer consisting of poly(ε-caprolactone) (PCL, as A block) and poly(cyclohexene oxide) (PCHO, as B block), namely PCL(PCHO)₂.