Synthesis and characterization of side‐chain liquid‐crystalline polyacrylates containing azobenzene moieties

Syntheses of novel liquid‐crystalline polymers containing azobenzene moieties were performed by a convenient route with an acrylate backbone. The azobenzenes were key intermediates of the monomers, and side‐chain liquid‐crystalline polymers were prepared, that is, poly[α‐{4‐[(4‐acetylphenyl)azo]phenoxy}alkyloxy]acrylates, for which the spacer length was 3 or 11 methylene units. In addition, poly[3‐{4‐[(3,5‐dimethylphenyl)azo]phenoxy}propyloxy]acrylate was prepared with a spacer length of 3 methylene units. The structures of the precursors, monomers, and polymers were characterized with Fourier transform infrared, ¹H‐NMR, and ¹³C‐NMR techniques. The polymers were obtained by conventional free‐radical polymerization with 2,2′‐azobisisobutyronitrile as an initiator. The phase‐transition temperatures of the polymers were studied with differential scanning calorimetry, and the phase structures were evaluated with a polarizing optical microscopy technique. The results showed that two of the monomers and their corresponding polymers exhibited nematic liquid‐crystalline behavior, and one of the monomers and its corresponding polymer showed smectic liquid‐crystalline behavior. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2653–2661, 2002     

Synthesis,characterization, and degradation of a novel L‐tyrosine‐derived polycarbonate for potential biomaterial applications

A novel class of pseudo‐poly(amino acid)s was synthesized with a cyclic dipeptide as new diphenole. Nonpeptide bonds alternating with a peptide bond structure were introduced into the backbone of the pseudo‐poly(amino acid)s. The cyclic dipeptide in this study was obtained from natural L ‐tyrosine. L ‐Tyrosine is a major nutrient amino acid with a phenolic hydroxyl group, so a polycarbonate derived from the cyclic dipeptide should possess more optimum mechanical properties, bioactivity, and biocompatibility. The hydrolytic specimen of the resulting polycarbonate was prepared by a modified solvent evaporation process. Under strongly alkaline conditions, degradation testing was performed. The tyrosine‐derived polycarbonate possessed a low glass‐transition temperature value and a high thermal decomposition temperature value, which formed a broad mean thermal processing range. The most important results of our study were the effects of the polycarbonate degradation on the local pH values, which were smaller than those of other biodegradable polymers [e.g., poly(lactic acid), poly(glycolic acid), and poly(lactic glycolic acid)]. The synthesized polymer and cyclic dipeptide were characterized with Fourier transform infrared, ¹³C‐NMR, and ¹H‐NMR spectroscopy to determine their chemical structures; by differential scanning calorimetry and thermogravimetric analysis to determine the thermal properties of the polymer; by gel permeation chromatography to determine the polymer's molecular weight; and by X‐ray diffraction to determine the polymer's morphology. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Organic acids catalyzed polymerization of ε‐caprolactone: Synthesis and characterization

Environmentally friendly organocatalytic synthesis of aliphatic polyesters was studied. The catalysis investigated is novel, and lends itself well to the potential production of valuable biodegradable products. The reactions were based on an organic acids‐catalyzed ring‐opening polymerization of ε‐caprolactone with fatty acid derivatives as the initiator and were performed in the absence of solvents. The chemical structures of the functionalized polymers were confirmed by ¹H and ¹³C‐NMR spectra. Polymers with different molecular weights, in the range 10,900–15,200 were obtained in the presence of fumaric acid as catalyst. The thermal properties of the functionalized PCLs were determined by modulated differential scanning calorimetry and thermogravimetric analysis. The MDSC results verified that the crystallinity and the melting point of the lipid‐functionalized polymers were lower than that of the unfunctionalized poly(ε‐caprolactone). The hydrolytic degradation of the functionalized polymer was also investigated. The result shows the degradation rate was affected by the presence of oleic acid derivatives in the polymer molecule. The lipid‐functionalized polymers synthesized by the metal‐free polymerization systems seem to be suitable biodegradable polyesters for use in biomedical and pharmacological applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and polymerization of unsaturated derivatives of thymol

Summary The preparation of methacrylic and p-styrenesulfonic acid esters of the antibacterial agent thymol (2-isopropyl-5-methylphenol) and their characterization by IR, ¹H and ¹³C NMR spectroscopy is described. The monomers are radically polymerizable and give polymers in which thymol is covalently attached to the polymer backbone by ester links.     

Synthesis and polymerization of unsaturated derivatives of halogenated phenols

Summary The preparation of p-styrenesulfonic and methacrylic acid esters of the microbiocides 2, 4, 6-trichlorophenol and 4-chloro-m-cresol, and their characterization by IR, ¹H and ¹³C NMR spectroscopy are described. The radical homopolymerization of the biocidal monomers, and their copolymerization with various vinyl monomers have been studied. The polymerization gives polymers in which the microbiocide moieties are covalently attached to the polymer backbone chain by ester links.     

On-line GPC/NMR experiments using the isotactic poly(methyl methacrylate) with well-defined chemical structure

Summary Gel permeation chromatography of. isotactic PMMA has been performed on a Chromatograph linked to a 500 MHz ¹H NMR spectrometer. ¹H NMR spectra of good resolution and high S/N ratio were collected over the entire Chromatographic peak. The Mn of the polymer sample can be directly determined by intensity measurements of the proton signals due to the endgroup and monomeric units, since the polymers used were prepared by the living polymerization initiated by t-C₄H₉MgBr. A good linear relation was obtained between the log(Mn) and elution time.     

Investigation of the chemical and morphological structure of thermally rearranged polymers

Reacting ortho-functional poly(hydroxyimide)s via a high-temperature (i.e., 350 °C–450 °C) solid-state reaction produces polymers with exceptional gas separation properties for separations such as CO₂/CH₄, CO₂/N₂, and H₂/CH₄. However, these reactions render these so-called thermally rearranged (TR) polymers insoluble in common solvents, which prevent the use of certain experimental characterization techniques such as solution-state nuclear magnetic resonance (NMR) from identifying their chemical structure. In this work, we seek to identify the chemical structure of TR polymers by synthesizing a partially soluble TR polymer from an ortho-functional poly(hydroxyamide). The chemical structure of this TR polymer was characterized using 1-D and 2-D NMR. By use of cross-polarization magic-angle spinning ¹³C NMR, the structure of the polyamide-based TR polymer was compared to that of a polyimide-based TR polymer with a nearly identical proposed structure. The NMR spectra suggest that oxazole functionality is formed for both of these TR polymers. Furthermore, gas permeation results are provided for the precursor polymers and their corresponding TR polymer. The differences in transport properties for these polymers result from differences in the isomeric nature of oxazole-aromatic linkages and morphological differences related to free volume and free volume distribution.     

Synthesis of UV-curable polysiloxanes containing methacryloxy/fluorinated side groups and the performances of their cured composite coatings

Three novel UV-curable polysiloxanes consisting of polysiloxane backbone with methacryloxy/fluorinated side groups were synthesized, and their structures were characterized by FT-IR, ¹H NMR and ¹³C NMR. A series of UV-cured composite coatings based on the synthesized polysiloxanes and an epoxy methacrylate were obtained through photopolymerization. Their gel content, flexibility, hardness, gloss, contact angle, thermal behavior as well as water absorption ratio were investigated. Results found that the siloxane component could enhance the flexibility and gloss of coatings, while the presence of fluorinated groups could improve the hardness. The combination of silicon and fluorine in the same polymer could increase thermal stability and water resistance of the coatings and decrease their surface energy simultaneously. The observation of the fractured-surface morphology showed that the polysiloxanes could be well dispersed in the epoxy methacrylate to some extent. A suitable addition of such polysiloxane in photocurable coating matrixes may provide excellent properties for the cured coatings and widen their applications.     

Indolo[3,2‐b]carbazole‐based poly(arylene vinylene)s. The influence of substitution position on spectroscopic and electrochemical properties

Three novel soluble poly(arylene vinylene)s containing indolo[3,2‐b]carbazole moiety inserted in the polymer chain at 2,8‐, 3,9‐ and 6,12‐positions were synthesized and used to study the influence of the linking topology on the optical and electronic properties. The new polymers were obtained through a palladium‐catalysed cross‐coupling Stille reaction between bis‐bromine[3,2‐b]indolocarbazoles and trans‐1,2‐bis(tributylstannyl)ethane in toluene. Polymers were soluble in chlorinated, aromatic and aprotic polar solvents. The structures of polymers were investigated using Fourier transform infrared, ¹H NMR and ¹³C NMR spectroscopies. The number‐average molecular weights determined using gel permeation chromatography are in the range (6.3–9.4) × 10³ g mol^?1 while thermogravimetric analysis showed the polymers to possess high thermal stability. UV‐visible and emission spectroscopy evidenced a bathochromic shift of λ_max for indolocarbazole linking topology in the polymer backbone, in the order: 6,12 < 2,8 < 3,9. Electrochemical properties were investigated by cyclic voltammetry using thin films cast on platinum disc working electrodes and highest occupied and lowest unoccupied molecular orbital energy levels were determined. © 2016 Society of Chemical Industry     

Synthesis of Oligomeric and Polymeric Ethers Containing the Cp*Ru+ and CpFe+ Metal Moieties

A variety of homometallic (Cp*Ru⁺) and heterometallic (CpFe⁺–Cp*Ru⁺) oligomers with one to five metal moieties were prepared in high yields (74–90%) via nucleophilic aromatic substitution reactions. For the mixed metal systems, it is shown that the arrangement of the metal moieties along the backbone can be controlled. In addition, the synthesis of heterometallic polymers is described, along with their decomplexation and thermal properties. It was found that the thermal properties and solubility of the systems are greatly dependent on the linkages within the polymer backbone.     

Hydrolytic degradation studies on poly(phosphate ester)s

Eight poly(phosphate ester)s comprising five homopolymers (polymers I–V), two copolymers (polymers VI and VII), and one terpolymer (polymer VIII) were synthesized by interfacial polycondensation of phenyl phosphorodichloridate with various bisphenols. The polymers were characterized by spectroscopic techniques. The copolymer and terpolymer ratios were determined by ¹H‐NMR spectroscopy. The molecular weights of the polymers were determined by end‐group analysis using ³¹P‐NMR spectroscopy. Accelerated hydrolytic degradation studies under alkali‐catalyzed conditions showed that the polymer from biphenol (polymer IV) is the most stable and the polymer from thiodiphenol (polymer V) is the least stable. The products of hydrolytic degradation were analyzed and a suitable mechanism for the degradation of the polymers proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 626–631, 2003     

Terpolymerization of Carbon Dioxide with Propylene Oxide and ε-Caprolactone: Synthesis, Characterization and Biodegradability

Summary An aliphatic polycarbonate, terpolymer of carbon dioxide, propylene oxide and ε-caprolactone(PPC-CL-PPO-CL),was synthesized by using a polymer supported bimetallic complex as a catalyst.The terpolymers prepared were characterized by FTIR, ¹H NMR, ¹³C NMR, DSC and WAXD measurements. The influences of various reaction conditions such as molar ratio of the monomers, reaction time and reaction temperature on the terpolymerization progress were investigated. The results showed that ε-caprolactone (ε-CL) was inserted into the backbone of poly(propylene carbonate)-poly(propylene oxide) (PPC-PPO) successfully. The viscosity and glass transition temperature of the terpolymers were much higher than PPC-PPO. ε-Caprolactone offered an ester structural unit that gave the terpolymers remarkable degradability. And the degradation rate of the backbone increased with the ε-CL inserted into the terpolymers.     

Effect of grafting degree and side PEO chain length on the ionic conductivities of NBR-g-PEO based polymer electrolytes

Comb-shaped graft polymers were synthesized and complexed with a LiCF₃SO₃ salt to form a new class of polymer electrolytes. The polymers based on an acrylonitrile-butadiene copolymer (NBR) have pendant, short-chain poly(ethylene oxide) (PEO) grafted onto a butadiene unit. The characteristics of these polymer electrolytes were investigated in terms of number of pendant EO groups and grafting degree in the graft copolymer. The maximum conductivity was observed at the optimum side PEO chain length, and the PEO chain length for the maximum conductivity decreased with an increase in the grafting degree. And a solid ⁷Li NMR relaxation technique was used to study the local environments and dynamics of the ions in the polymer electrolytes. The maximum conductivity value obtained from our study was three orders of magnitude higher than that of classical PEO-based electrolytes at ambient temperature. These improved low temperature conducting polymers with higher relative mechanical strength are expected to be suitable for practical applications, such as in rechargeable lithium batteries or electrochromic devices.     

Cross-linked degradable poly(β-thioester) networks via amine-catalyzed thiol-ene click polymerization

A set of binary and ternary biodegradable cross-linked poly(β-thioester) networks have been synthesized via thiol-ene Michael additions, by reacting combinations of dithiols, diacrylates and multifunctional cross-linkers. Insoluble binary thermoset networks and soluble ternary branched polymers with broad molar mass distributions are obtained in a facile manner after polymerization at room temperature for only few minutes. The networks display excellent thermal stability up to 250 °C and exhibit low glass transition temperatures. The soluble branched polymers show degradation of the polyester backbone upon chemical degradation by acidic and basic solutions. Finally, the (bio)degradability of ternary PBT polymer films is examined via quartz crystal microbalance measurements. Weight loss is measured as a function of time upon exposure to phosphate buffers at different pH. PBTs carrying apolar chain segments display surface degradation, while PBTs with more polar ethylene glycol segments allow for swelling in aqueous solution, which is reflected in concomitant surface and bulk degradation of the materials. Because of their biodegradability, these easy to synthesize poly(β-thioesters) networks are considered to be suitable candidates to use in future biomedical or ecological applications.     

Structural and electronic properties of poly(3-thiophen-3-yl-acrylic acid)

This work presents a combined theoretical and experimental study of poly(3-thiophene-3-yl acrylic acid), a new polythiophene derivative soluble in polar solvents. Quantum chemical calculations on small oligomers were performed to propose a structural model for this polymer. Specifically, the minimum energy conformations and the rotational profiles of the different isomeric derivatives constructed for a model system formed by two monomeric units were calculated. The resulting model, which shows head-to-tail polymer linkages and the acrylic acid side group arranged in trans-conformation, were used to predict the π-π^∗ lowest transition energy of an infinite polymer chain. On the other hand, the polymer was prepared by chemical oxidative coupling using anhydrous ferric chloride and subsequent alkaline hydrolysis. The synthetized material, which is soluble in aqueous base and acetone solutions, was characterized by FTIR, ¹H NMR and UV-vis experiments. Both the structural information and electronic properties derived from such experiments are fully consistent with the theoretical model obtained using quantum mechanical calculations.     

Synthesis of a novel linear water‐soluble β‐cyclodextrin polymer

A novel linear water‐soluble β‐cyclodextrin polymer has been prepared by grafting β‐cyclodextrin on poly[(methyl vinyl ether)‐alt‐(maleic anhydride)]. First, lithium hydride was used to obtain the mono‐alkoxide β‐CD. Grafting of β‐CD derivatives to the polymer backbone was then carried out by an esterification method. Using this method, polymers containing various amounts of β‐CD were synthesized. The resulting grafted polymers were characterized by two complementary methods, ¹H NMR and IR spectroscopy. The first was used to calculate the degree of substitution for the low amounts of β‐CD. The second method was very useful to evaluate the degree of substitution and the molar ratio of CD especially for high amounts of grafting. Our results indicate good agreement between both methods for intermediate rates. Copyright © 2004 Society of Chemical Industry     

Synthesis of new versatile functionalized polyesters for biomedical applications

A new family of branched polymers was synthesized for different biomedical applications such as the preparation of targeted nanoparticulate drug carriers. They are new copolymers of hydroxy-acids and allyl glycidyl ether. The functional groups (allyl-, hydroxyl- and carboxyl-) to which various groups will be grafted are linked to the polymer backbone. The resulting polymers were characterized by ¹H NMR, ¹³C NMR, size exclusion chromatography (SEC), elemental analysis and differential scanning calorimetry (DSC). In vitro cytotoxicity assays were also conducted to ensure biocompatibility of the polymers. In order to obtain some structural evidences, different molecules have been grafted on the pendant groups. The method allows a rapid and easy synthesis of allyl-, hydroxyl- and carboxyl-branched degradable polymers for grafting various bioactive molecules.     

Surface imprinted polymers recognizing amino acid chirality

A highly enantioselective polymer was prepared for the separation of optically active tryptophan methylester by a surface molecular imprinting technique. An organophosphorus compound was found to be effective as a functional host molecule for recognizing the chirality of the amino acid ester. The imprinted polymers exhibited a higher template effect toward the corresponding imprinted tryptophan methylester than its isomer and analogues, while a reference polymer prepared without an imprinting molecule did not show any selectivity toward the enantiomers. The enantioselective recognition was quantitatively evaluated by determination of the binding constants of the D ‐ and L ‐tryptophan methylester to the imprinted polymers. Furthermore, the mechanism for producing enantioselectivity was deduced from FTIR and ¹H‐NMR spectra. Based on the results obtained we concluded that the enantiomeric selectivity was mainly caused by electrostatic and hydrogen bonding interactions between the functional organophosphorus molecule and the target tryptophan methylester on the polymer surface. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 695–703, 2000     

Investigation on thermotropic liquid crystalline and photocrosslinkable polyarylidene arylphosphate esters containing cyclohexanone units

Two series of novel liquid crystalline-cum-photocrosslinkable divanillylidene cyclohexanone containing polymers have been synthesized from 2,6-bis[m-hydroxyalkyloxy(vanillylidene)]cyclohexanone [m=6, 8, 10] with different arylphosphorodichloridates (naphthyl, biphenyl) by solution polycondensation method at ambient temperature. Their chemical structures were confirmed by FT-IR, ¹H, ¹³C and ³¹P NMR spectroscopy. The intrinsic viscosity values were measured to find out molecular weight of the synthesized polymers. The mesogenic properties and phase behaviors were investigated with differential scanning calorimetry and hot stage optical polarized microscopy. The experimental results demonstrated that the mesogenic transition and isotropization temperature gradually decreases with increase in even number of methylene spacer of the polymer chain. All the polymers showed anisotropic behavior under hot stage optical polarized microscope (HOPM). The thermal behaviors of the polymers were studied by thermogravimetric analysis and stable between 292 and 330 °C. The photocrosslinking of the polymers was investigated in thin film by UV light/UV spectroscopy and the cyclobutane ring formation via 2π-2π cycloaddition reactions of the divanillylidene exo-cyclic double bond of the polymer backbone. The pendant naphthyloxy containing polymers show faster crosslinking than the pendant biphenyloxy containing polymers.     

Synthesis and characterization of fluoropoly(amide–sulfonamide)s via polycondensation

Novel fluorine-containing polymers, fluoropoly(amide–sulfonamide)s were synthesized for the first time by polycondensation from β-hydroxytetrafluoroethanesulfonic acid sultone (TFE-sultone) and hexamethylenediamine. The chemical structures of the obtained F-PASAs were characterized by intrinsic viscosity measurements, GPC, FTIR, ¹H NMR, ¹⁹F NMR and element analysis in detail. Thermal properties and optical property of F-PASAs were investigated by DSC, DMA, TGA and UV–vis spectra, respectively. The investigation indicated that these functional fluoropolymers in which there are both amide and sulfonamide linkages along the polymer main chains possessed distinctive structure as well as unique properties such as thermal properties, clean and high transparency and compatibility with nylons.