Synthesis and optical properties of a crosslinkable polymer system containing tricyanofuran‐based chromophores with excellent electro‐optic activity and thermal stability

Crosslinkable polymers with side‐chain systems were investigated in order to increase the content of nonlinear optical chromophores and improve the stability of oriented chromophores. A series of crosslinkable copolymers having varying concentrations of chromophores with tricyanofuran as an acceptor were successfully synthesized and characterized. The crosslinked electro‐optic (EO) polymers revealed the highest EO coefficient (r₃₃) of 47.0 pm V^?1 at 1310 nm, which was similar to r₃₃ of uncrosslinked systems. Compared to the uncrosslinked EO polymer systems, the crosslinked ones exhibited significantly enhanced temporal stability. The results of the EO coefficients and thermal properties indicated that the crosslinking effectively improved the stability and did not influence the r₃₃ values. Copyright © 2012 Society of Chemical Industry     

pH‐sensitive acrylic‐based copolymeric hydrogels for the controlled release of a pesticide and a micronutrient

Acrylic‐based copolymers of methyl methacrylate (MMA) and methacrylic acid (MAA) have been prepared by solution and bulk polymerization techniques using benzoyl peroxide (BPO) as an initiator. Three polymers were prepared with a varying ratio of MMA/MAA. In an effort to increase the hydrophilicity of the matrix, one MMA/MAA polymer was prepared by adding an additional amount of 2‐hydroxy ethyl methacrylate (HEMA). All the polymers were crosslinked in situ by ethylene glycol dimethacrylate (EGDMA). These polymers were characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry. Viscous flow characteristics were determined from solution viscosity and rheological measurements. Dynamic and equilibrium swelling experiments were carried out under varying pH conditions (i.e., 0.1N NaOH, 0.1N HCl, and double‐distilled water). Partially crosslinked hydrogels show varying hydrophilicity because of the presence of carboxylic acid groups making them pH‐responsive. Swelling increased with an increasing number of —COOH groups on the polymer backbone and the hydrophilicity varied with changing pH. Cypermethrin, a widely used pesticide, and cupric sulfate, a model micronutrient, were loaded into these pH‐sensitive hydrogels to investigate their controlled release characteristics. The in vitro release rates of both compounds have been carried out under static dissolution conditions at 30°C. Release data have been fitted to an empirical relation to estimate transport parameters. The release results have been discussed in terms of the varying hydrophilicity of the hydrogel network polymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 394–403, 2003     

Synthesis,characterization, and properties of new 3‐hexyl‐2,5‐diphenylthiophene: Phenylene vinylenes copolymers as colorimetric sensor for iodide anion

Four new conjugated copolymers P1 ‐ P4 have been prepared by the Horner‐Emmons and Knoevenagel polymerization reactions. P1 ‐ P4 were characterized by NMR, FTIR, cyclic voltammetry (CV), diffuse reflectance UV–vis spectroscopy (DR UV–vis), and thermal gravimetric analysis (TGA). The optical band gaps of these polymers, calculated from the onset absorption edge, were found between 2.15 and 2.34 eV. The band gaps calculated by CV were ranged between 1.94 and 2.57 eV. The presence of nitrile moiety on the phenylene vinylene unit is believed to influence the optical properties of these polymers, i.e., P3 and P4 have shown lower band gaps than P1 and P2 . All polymers possess good iodide anion sensing property over a wide range of other anions (F^?, Cl^?, Br^?, , CN^?), indicating their promise in fabricating selective iodide sensors. The initial colorless solution of polymers in THF changed to deep yellow upon the addition of aqueous solution of iodide salts along with significant changes in the UV–vis spectra of the polymers. The limit of detection (LOD) for P1‐P4 were found between 0.43 and 2.54 mM . These polymers constitute long alkoxy and alkyl side chains, bearing excellent solubility in most common organic solvents which warrants their suitability for photovoltaic devices application. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44948.     

Electrochemical copolymerization and stability of crosslinked bis[1,2‐(pyrrol)ethoxy]ethane with pyrrole

The copolymers, pyrrole‐co‐bis[1,2‐(pyrrol)ethoxy]ethane (PEE), were produced by electropolymerization in acetonitrile (containing 0.1 mol L⁻¹ lithium perchlorate). The properties and morphology of these polymers were investigated by cyclic voltammetry, UV–vis absorption spectra and scanning electron microscopy (SEM), respectively. The results exhibit that the cyclic voltammograms and rates of electropolymerization of the prepared copolymers were significantly affected by PEE concentration in water and acetonitrile solution. Higher applied potential was required for the polymerization with decreasing the ratio of pyrrole/PEE. This was ascribed to the steric hindrance of high concentration of N‐substituted groups. The SEM images of the poly(pyrrole‐co‐PEE) and PPEE films show more compact and more smooth morphology compared with that of PPy and cyclic voltammogram of the poly(pyrrole‐co‐PEE) films, which display good electrochemical stability in the mixed solution, indicating that the modification of crosslinked structure was effective for the stabilization of the redox cycles. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Novel copolyesters containing naphthalene structure III. Copolyesters prepared from 2,6‐dimethyl naphthalate,ethylene glycol,and 2,2‐dialkyl‐1,3‐propanediols

Poly(ethylene naphthalate) (PEN) copolymers were prepared by melt polycondensation of dimethyl naphthalate and excess ethylene glycol with 5–40 mol % (in feed) of 1,3‐propanediol or 2,2‐dialkyl‐1,3‐propanediols, where the dialkyl groups are dimethyl, diethyl, and butyl‐ethyl. No significant depression of reduced specific viscosity was observed. The comonomer contents in the copolymers are considerably higher than those in the feed. The effects of the copolymer composition on the structures of the films were investigated using thermal analyses, density measurements, X‐ray diffraction methods, and other physical tests. The crystallinities and densities of heat‐treated films decreased with increasing content of comonomer and length of alkyl side chain in the comonomer. The glass transition temperature (T_g) and melting temperature (T_m) were decreased by the copolymerization, while an increase in the length of the alkyl side chain hardly affected T_ms of the heat‐treated films. Alkali resistance, moisture resistance, dye ability, and thermal shrinkage were increased by the incorporation of comonomer having an alkyl side chain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2754–2763, 2001     

Benzoin‐terminated polyurethane as macrophotoinitiator for synthesis of polyurethane–polymethyl methacrylate block copolymers

Macromolecular photoinitiators have attracted much attention in the recent years. They combine the properties of polymers with those of low‐molecular weight photoinitiators. These are polymers having side‐ or main‐chain photoreactive groups and can be used to make tailor‐made graft and block copolymers. Benzoin is an important photoinitiator, and polymers containing terminal photoactive benzoin group can initiate polymerization of vinylic monomers to give block copolymers. In the present case, we report the synthesis of polyurethane macrophotoinitiator with benzoin end group, which was subsequently used to synthesize polyurethane–polymethyl methacrylate block copolymers. The block copolymers were characterized by FTIR, ¹H NMR, TGA, scanning electron microscopic analysis, and solution viscometry studies. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and properties of random copolymers of 2,2‐dimethyltrimethylene carbonate and ethylene carbonate catalyzed by lanthanide tris(2,6‐di‐tert‐butyl‐4‐methylphenolate)

Random copolymers of 2,2‐dimethyltrimethylene carbonate and ethylene carbonate (EC) were synthesized with lanthanide tris(2,6‐di‐tert‐butyl‐4‐methylphenolate)s [Ln(DBMP)₃; Ln = La, Nd, Sm, or Dy] as catalysts, among which La(DBMP)₃ showed the highest activity. Poly(2,2‐dimethyltrimethylene carbonate‐co‐ethylene carbonate)s [poly(DTC‐co‐EC)]s with high molecular weights were prepared at room temperature and characterized with ¹H‐NMR and size exclusion chromatography. The thermal behavior and crystalline properties of the poly(DTC‐co‐EC)s were analyzed with differential scanning calorimetry, thermogravimetric analysis, and X‐ray diffraction. The crystallinity and melting temperatures of the poly(DTC‐co‐EC)s both decreased with increasing EC content in the copolymers. The mechanical properties of these copolymers were also investigated with dynamic mechanical analysis and tensile strength measurements, which revealed that a reduction of the glass‐transition temperature and great enhancement of the tensile properties could be achieved with higher EC contents. These improvements in the thermal and mechanical properties indicate potential applications in biomedical research for novel polycarbonates. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Controlled/living RAFT polymerization of N‐phenyl maleimide and synthesis of its block copolymers

The controlled/living radical polymerization of N‐phenyl maleimide (NPMI) was achieved using 2,2′‐azobisisobutyronitrile as the initiator and 2‐cyanopropyl‐2‐yl dithiobenzoate as the reversible addition‐fragmentation chain transfer agent at 75°C in dichloroethane/ethylene carbonate (60/40, w/w) mixed solvent. The block copolymers of polystyrene‐b‐polyNPMI and poly(n‐butyl methacrylate)‐b‐polyNPMI were successfully prepared by chain extension from dithiobenzoate‐terminated polystyrene and poly (n‐butyl methacrylate) to NPMI, respectively. The obtained NPMI‐based (co)polymers were characterized by gel permeation chromatography and ¹H‐NMR spectroscopy. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of binary blends composed of poly(dioctylfluorene‐alt‐hexylsulfonylthiophene) and nonconjugated polymers

The solutions and the thin films of poly[9,9‐dioctyl‐2,7‐fluorene‐alt‐2,5–(3‐hexyl‐sulfonylthiophene)] (PFSO₂T) and its binary blends with other nonconjugated polymers such as poly(methyl methacrylate) (PMMA), polycarbonate (PC), and ethylene vinyl acetate copolymer (EVA) can be prepared by different concentrations from a polymer solution. Binary polymer blends can increase the absorbance and photoluminescence intensities in the solid state due to nonconjugated polymers can act as dispersion agents which can reduce the interchain interaction or the aggregation of the conjugated polymers. Photoluminescence intensity of the thin films of fluorescent polymers blending with ethylene vinyl acetate copolymers exhibited six times higher than that of the neat fluorescent polymers. The PFSO₂T/EVA binary blends reveal the least extent of optical degradation of around 20% compared to those binary blends in both absorption and emission intensities after the irradiation under the UV‐light for 20 h. The cross‐sectional morphology of fluorescent polymers blending with ethylene vinyl acetate copolymers reveals little aggregation and better phase separation among the other binary polymer blends. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44969.     

Synthesis of trimethylene carbonate/ϵ‐caprolactone copolymers initiated with zinc alkoxide: influence of copolymer chain microstructure on thermal and mechanical properties

Ethylzinc(II ) ethoxide is a highly active and efficient initiator for the bulk polymerization of 1,3‐trimethylene carbonate and its copolymerization with ? ‐caprolactone. This initiator allows one to obtain (co)polymers with high molar masses in quite a short time. Significant difference in co‐monomer reactivity and relatively low participation of intermolecular transesterification processes lead to the obtained copolymers being characterized by a gradient chain microstructure. In ¹³C NMR spectra, in all regions, we observed the presence of triads which were distinctly represented by four peaks for the carbonyl signal. Mechanical tests showed that copolymers containing 70% and more of ? ‐caprolactone presented a relatively high Young's modulus and a very high maximum elongation factor; therefore these materials are promising in many biomedical applications. Due to the high reaction rate, we also made an attempt at copolymerization using reactive extrusion which gave promising results. © 2017 Society of Chemical Industry     

Phase behavior of side‐chain liquid‐crystalline elastomers and their precursors containing para‐nitro azobenzene

Side‐chain liquid‐crystalline copolymethacrylates (PMm's), containing para‐nitro azobenzene as the mesogenic group and 2‐hydroxylethyl methacrylate (HEMA) as a comonomer, were synthesized by radical polymerization, and their corresponding liquid‐crystalline elastomers (LCEm's) were prepared through chemical crosslinking. All of the polymers (PMm's) and the elastomers studied showed enantiotropic smectic A phases; the clearing temperature (T_i) of the PMm polymers decreased with increasing amount of HEMA, and the T_i of the corresponding LCEm's decreased compared to that of their precursors. Small‐angle X‐ray scattering studies on the copolymers quenched from their liquid‐crystalline phases indicated that the characteristic distance increased with increasing amorphous component content and thus, the amorphous components were in between the smectic layers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2275–2279, 2003     

Thermoresponsive hydrogels based on sucrose 1‐O′‐methacrylate and N‐isopropylacrylamide: Synthesis,properties, and applications

Chemically crosslinked hydrogels composed of carbohydrate‐based and thermoresponsive monomers, sucrose 1‐O′‐methacrylate (SMA), sucrose dimethacrylate, and N‐isopropylacrylamide, respectively, were synthesized by free radical polymerization. These materials were characterized with respect to their composition, thermoresponsiveness, porosity, degradability, and as drug and protein delivery systems. Swelling studies, thermomechanical analysis, and differential scanning calorimetry showed that the lower critical solution temperature behavior of the hydrogels can be controlled by the SMA amount in the copolymers. On the other hand, thermoporometry showed that the pore size is somewhat dependent on the composition, which is confirmed by scanning electron microscopy. Hydrolytic degradation studies indicated that SMA side chains, as well as the crosslinker (sucrose dimethacrylate), are hydrolysable at corporeal temperature and pH 10, and the water swelling capability of the resulting materials increases as the hydrolysis degree increases. Finally, protein delivery studies revealed that the kinetics of release can be tailored by the copolymer composition. The results of this study suggest the potential application of these hydrogels in drug delivery systems and tissue engineering. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45495.     

Synthesis and tunable thermoresponsive solution morphologies of 2,2‐bis‐methylolpropionic acid dendron–azobenzene–poly(N‐isopropyl acrylamide) copolymers

Amphiphilic temperature‐ and photoresponsive linear–dendritic block copolymers comprising second‐generation acetonide‐2,2‐bis‐methylolpropionic acid‐based polyester dendron and linear poly(N‐isopropyl acrylamide) (PNIPAM) linked by an azobenzene unit were synthesized using atom transfer radical polymerization (ATRP) followed by click chemistry. Linear PNIPAM precursor was prepared from an azide‐functionalized azobenzene containing ATRP initiator. Two polymers obtained by varying the chain length of the PNIPAM block showed different morphologies and lower critical solution temperature (LCST) values in aqueous solution. Complete change in morphology of the two polymers into large spherical aggregates and nanotubes, respectively, was observed upon heating the micellar solution above LCST. The azobenzene unit was found to undergo trans–cis photoisomerization in the assemblies and caused a change in the microenvironment of an encapsulated hydrophobic dye without any release. Acetonide groups on the dendron were deprotected to afford hydroxylated polymer that showed well‐defined morphologies above the LCST and after heating–cooling cycle while significant dye encapsulation was seen only above the LCST. © 2017 Society of Chemical Industry     

Poly(amide‐hydrazide)s–graphene composites synthesis and characterization

Poly(amide‐hydrazide)s copolymers were prepared using hydrazide derivative of phenylene diamine to react with aromatic diacid chloride. The wholly aromatic poly(amide‐hydrazide)s have better solubility in organic polar solvents, such as N ,N‐dimethylacetamide, dimethylsulfoxide, 1‐methyl‐2‐pyrollidone, and N ,N‐dimethylformamide, at room temperature, while still maintaining their high thermal stability. Graphene in the nano size was used as a filler to enhance their thermal and mechanical properties. The polymers as well as the composite were characterized by spectral and mechanical tools as well as by X‐ray analysis. POLYM. COMPOS., 38:1311–1318, 2017. © 2015 Society of Plastics Engineers     

Synthesis of amphiphilic temperature‐sensitive poly(N‐isopropylacrylamide)‐block‐poly(tetramethylene carbonate) block copolymers and micellar characterization

Amphiphilic thermally sensitive poly(N‐isopropylacrylamide)‐block‐poly(tetramethylene carbonate) block copolymers were synthesized by ring‐opening polymerization of tetramethylene carbonate with hydroxyl‐terminated poly(N‐isopropylacrylamide) (PNiPAAm) as macro‐initiator in the presence of stannous octoate as catalyst. The synthesis involved PNiPAAm bearing a single terminal hydroxyl group prepared by telomerization using 2‐hydroxyethanethiol as a chain‐transfer agent. The copolymers were characterized using ¹H NMR and Fourier transform infrared spectroscopy and gel permeation chromatography. Their solutions show reversible changes in optical properties: transparent below the lower critical solution temperature (LCST) and opaque above the LCST. The LCST depends on the polymer composition and the media. Owing to their amphiphilic characteristics, the block copolymers form micelles in the aqueous phase with critical micelle concentrations (CMCs) in the range 1.11–22.9 mg L^?1. Increasing the hydrophobic segment length or decreasing the hydrophilic segment length in the amphiphilic diblock copolymers produces lower CMCs. A core‐shell structure of the micelles is evident from ¹H NMR analyses of the micelles in D₂O. Transmission electron microscopic analyses of micelle morphology show a spherical structure of both blank and drug‐loaded micelles. The blank and drug‐loaded micelles have an average size of less than 130 nm. Observations show high drug‐entrapment efficiency and drug‐loading content for the drug‐loaded micelles. Copyright © 2010 Society of Chemical Industry     

A study of pyridinium‐type functional polymers. III. Preparation and characterization of insoluble pyridinium‐type polymers

The copolymers of 4‐vinylpyridine (4VP), styrene (St) and divinylbenzene (DVB) with varied compositions, P(4VP‐St‐DVB), were synthesized by suspension polymerization using 2,2′‐azobisisobutyronitrile (AIBN) as an initiator. The insoluble (crosslinked) pyridinium‐type polymers in benzyl–pyridinium bromide form, which possess various macromolecular chain compositions, were prepared by the reaction of each P(4VP‐St‐DVB) with benzyl bromide (BzBr), respectively. By using different halohydrocarbon RX in the quaternization of P(4VP‐St‐DVB), the insoluble pyridinium‐type polymers with various pyridinium group structures were obtained. The structures of P(4VP‐St‐DVB) and its quaternized product Q‐P(4VP‐St‐DVB) were identified by FTIR. The 4VP content in each copolymer P(4VP‐St‐DVB) was measured by nonaqueous titration; and the pyridinium group content (C_q) in each Q‐P(4VP‐St‐DVB) sample was determined by means of the back titration manner in argentometry and/or the elemental analysis method, respectively. In addition, the particle structure and the surface morphology of the thus‐prepared polymer were observed using SEM. According to a series of experimental results, the preparation and characterization of insoluble pyridinium‐type polymers are analyzed and discussed. This work can prepare the ground for a study on the antibacterial activity of insoluble pyridinium‐type polymers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 668–675, 2000     

Silver‐ and gold‐labeled colloidal and crosslinked glycopolymers based on glycyl glycosynthons and maleic anhydride copolymers for lectin binding

A simple, convenient, and inexpensive technique for preparing lectin‐specific nanogold‐ and silver‐labeled colloidal and crosslinked neoglycoconjugates, based on maleic anhydride copolymers, was developed. Water‐soluble nanogold‐ and silver‐labeled glyconanoparticles were obtained in two steps: (1) introduction of free N‐acetyl‐D‐glucosamine or glycyl‐spacered glycosynthons—β‐N‐glycyl‐N‐acetyl‐D‐glucosamine or β‐N‐glycyl‐lactose—into poly(ethylene‐alt‐maleic anhydride) or poly(N‐vinylpyrrolidone‐alt‐maleic anhydride) and (2) labeling in situ the thus‐obtained glycopolymers with gold or silver nanoparticles. Lectin sorbents were synthesized from glycyl‐spacered glycosynthons and spherical, granulated, crosslinked maleic anhydride copolymers in an aqueous system without any condensing agents. Thus, maleic anhydride copolymer was used solely, without any preliminary modification of the polymer, as a matrix for crosslinking, for specific ligand binding, and as metal nanoparticles as a stabilizing cover. The resulting colloidal gold or silver glyconanoparticles were used as lectin sensors (in a dot‐blot analysis of lectins) and as crosslinked neoglycoconjugates for lectin sorption studies. The corresponding gold‐ or silver‐labeled water‐soluble glyconanoparticles and crosslinked neoglycoconjugates manifested high activity and specificity in all tests with a series of β‐D‐GlcNAc‐specific and β‐D‐Gal‐specific lectins. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44718.     

Synthesis and properties of polycarbonate copolymers of trimethylene carbonate and 2‐phenyl‐5,5‐bis(hydroxymethyl) trimethylene carbonate

The polycarbonate copolymers poly[trimethylene carbonate‐co‐2‐phenyl‐5,5‐bis(hydroxymethyl) trimethylene carbonate] [P(TMC‐co‐PTC)] were synthesized by the ring‐opening polymerization of trimethylene carbonate (TMC) and 2‐phenyl‐5,5‐bis(hydroxymethyl) trimethylene carbonate (PTC) with tin(II) 2‐ethylhexanoate and aluminum isopropoxide as the catalysts. These copolymers were further reduced by a palladium/carbonate (Pd/C; 10%) catalyst to produce partly deprotected copolymers. These two types of copolymers were characterized by ¹H‐NMR, Fourier transform infrared spectroscopy, UV spectroscopy, gel permeation chromatography, differential scanning calorimetry, and an automatic contact angle meter. The influences of the feed molar ratio of the monomers, the catalyst concentration, the reaction time, and the reaction temperature on the copolymerization process were also studied. The copolymerization of the TMC and PTC monomers was a nonideal copolymerization, and the copolymerization reactivity ratio of TMC was higher than that of PTC. In vitro degradation tests indicated that the partly deprotected copolymers possessed faster degradation rates and more hydrophilicity than the corresponding unreduced copolymers. Moreover, the degradation of these two type copolymers increased when the pH value of the buffer solutions decreased. In vitro drug‐release experiments showed that these two types of copolymers had steady drug‐release rates and good controlled release properties. Moreover, the partly deprotected copolymers had faster drug‐release rates than the corresponding unreduced copolymers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

High‐Molecular‐Weight Polyoxirane Copolymers and their Use in High‐Performance Dye‐Sensitized Solar Cells

Low‐crystalline random and gradient P(EO‐co‐PO) copolymers and amorphous PPO and PBO of high molecular weight were synthesized by anionic coordination polymerization. Polymer gel electrolytes based on these (co)polymers were prepared and tested for long‐term performance of DSSC. The DSSC based on P(EO‐co‐PO) copolymers have longer life time compared to the homo‐PEO‐ and homo‐PPO‐based DSSC, respectively. The cells containing the chemically crosslinked copolymer gel exhibited a high efficiency of 6% after 25 d performance, whereas the solar cells based on physically crosslinked copolymer gel showed fast degradation.

     

Dual lower critical solution temperature polymer networks based on block,laminate, and interpenetrating network structures composed of N‐alkylacrylamides and N,N‐dialkylaminoethyl methacrylates

Novel materials that display two lower critical solution temperatures (LCSTs) were developed by forming block copolymers, laminate structures, and interpenetrating networks of crosslinked polymer systems that displayed temperature sensitivity independently. A number of LCST polymers and copolymers were investigated, including those based on N‐isopropylacrylamide, N,N‐diethylacrylamide, N,N‐diethylaminoethyl methacrylate, and N,N‐dimethylaminoethyl methacrylate. The polymer structure was found to profoundly influence the thermal sensitivity, as polymer formulation techniques led to materials with varying degrees of temperature sensitivity. Random and block copolymerization, along with interpenetrating networks and laminate systems, were studied, with only the structures having the greatest physical separation between pendent chains of different types having the ability to separate temperature transitions. Experiments were conducted to characterize the equilibrium swelling behavior and thermal transitions in the polymer systems. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2974–2981, 2003