Synthesis and characterization of poly(meth)acrylates containing tricyanocyclopropane ring for piezoelectric applications

Summary p-(2,2,3-Tricyano-3-carbomethoxycyclopropyl)phenoxyethyl acrylate (5a) and p-(2,2,3-tricyano-3-carbomethoxycyclopropyl)phynoxyethyl methacrylate (5b) were prepared by the reactions of bromomalononitrile with methyl p-(2-acryloyloxyethoxy)benzylidene-cyanoacetate (4a) and methyl p-(2-methacryloyloxyethoxy)benzylidenecyanoacetate (4b), respectively. Monomers 5a and 5b were polymerized with free-radical initiators to obtain the polymers with multicyanocyclopropane functionalities in the pendant group. The resulting polymers 6a and 6b were soluble in acetone and the inherent viscosities were in the range of 0.20–0.25 dL/g. Solution-cast films showed T _g values in the range of 130–150°C and piezoelectric coeffcients (d₃₁) of the poled films were 1.5–1.6 pC/N, which are acceptable for piezoelectric device applications. Received: 28 April 2000/Accepted: 26 June 2000     

Synthesis of novel polyurethanes containing dioxybenzylidenecyanoacetate,as non‐linear optical chromophores and their properties

Methyl 3,4‐di‐(2′‐hydroxyethoxy)benzylidenecyanoacetate (3) was prepared by hydrolysis of methyl 3,4‐di‐(2′‐vinyloxyethoxy)benzylidenecyanoacetate (2). Diol 3 was condensed with 2,4‐toluenediisocyanate, 3,3′‐dimethoxy‐4,4′‐biphenylenediisocyanate, and 1,6‐hexamethylenediisocyanate to yield polyurethanes 4, 5 and 6 containing the non‐linear optical (NLO) chromophore 3,4‐dioxybenzylidenecyanoacetate. The resulting polyurethanes 4–6 were soluble in common organic solvents such as acetone and DMF. T_g values of the polymers obtained from DSC thermograms were in the range 80–102 °C. Polymers 4–6 showed thermal stability up to 300 °C in TGA thermograms, and electro‐optic coefficients (r₃₃) of the poled polymer films were in the range 10–12 pm V^?1 at 633 nm, which are acceptable for NLO device applications. © 2002 Society of Chemical Industry     

Synthesis and characterization of novel polyurethanes containing tricyanocyclopropane ring for piezoelectric applications

Summary 1-(2',2',3'-Tricyano-3'-carbomethoxycyclopropyl)-3,4-di-2'-hydroxyethoxybenzene (4) was prepared by the reaction of bromomalononitrile with methyl 3,4-di-(2'-hydroxyethoxy)benzylidenecyanoacetate (3). Diol 4 was condensed with 3,4-toluenediisocyanate and 3,3'-dimethoxy-4,4'-biphenylenediisocynate to yield polyurethanes 5 and 6 containing multicyanocyclopropane functionalities in the pendant group. The resulting polymers 5 and 6 were soluble in common organic solvents and the inherent viscosities were in the range of 0.25–0.30 dL/g. Polyurethanes 5 and 6 showed a thermal stability up to 300°C in TGA thermograms. Solution-cast films showed T _g values in the range of 100–130°C and piezoelectric coeffcients (d₃₁) of the poled polymer films were 1.8–2.0 pC/N, which are acceptable for piezoelectric device applications. Received: 14 December 2000/Accepted: 22 January 2001     

Synthesis and electro‐optical properties of novel Y‐type polyurethanes containing dioxynitrostilbene

3,4‐Di‐(2′‐hydroxyethoxy)‐4′‐nitrostilbene (2) was prepared by the reaction of 2‐iodoethanol with 3,4‐dihydroxy‐4′‐nitrostilbene. Diol 2 was condensed with 2,4‐toluenediisocyanate, 3,3′‐dimethoxy‐4,4′‐biphenylenediisocyanate and 1,6‐hexamethylenediisocyanate to yield novel Y‐type polyurethanes 3–5 containing dioxynitrostilbene as a non‐linear optical (NLO)‐chromophore. Polymers 3–5 were soluble in common organic solvents, such as acetone and DMF. These polymers showed thermal stability up to 280 °C in TGA thermograms with T_g values in the range of 100–143 °C in DSC thermograms. The approximate lengths of aligned NLO‐chromophores of the polymers estimated from AFM images were around 2 nm. The SHG coefficients (d₃₃) of poled polymer films were around 4.5 × 10^?8 esu. Poled polymer films had improved temporal and long‐term thermal stability owing to the hydrogen bonding of urethane linkage and the main‐chain character of the polymer structure, which are acceptable for NLO device applications. Copyright © 2004 Society of Chemical Industry     

Steric effect in the free radical polymerization of vinyl ethers containing electron-deficient olefin groups

Summary o-(2-Vinyloxyethoxy)benzylidenemalononitrile (3a), methyl o-(2-vinyloxyethoxy)benzylidenecyanoacetate (3b), 1,3-di-(2'-dicyanovinyl)-5-methyl-2-(2'-vinyloxyethoxy)benzene (4a), methyl 1,3-di-(2'-carbomethoxy-2'-cyanovinyl)-5-methyl-2-(2'-vinyloxyethoxy)benzene (4b), 2,3,4-tri-(2'-vinyloxyethoxy)benzylidenemalononitrile (5a), methyl 2,3,4-tri-(2'-vinyloxyethoxy)benzylidenecyanoacetate (5b), 2,4,6-tri-(2'-vinyloxyethoxy)benzylidenemalononitrile (6a), and methyl 2,4,6-tri-(2'-vinyloxyethoxy)benzylidenecyanoacetate (6b) were prepared by the condensation of o-(2-vinyloxyethoxy) benzaldehyde (1a), 2-(2'-vinyloxyethoxy)-5-methylisophthaldehyde (1b), 2,3,4-tri-(2'-vinyloxyethoxy)benzaldehyde (2a), 2,4,6-tri-(2'-vinyloxyethoxy)benzaldehyde (2b) with malononitrile or methyl cyanoacetate, respectively. Vinyl ether compounds 3a–b and 5a–b were polymerized readily by free radical initiators to give optically transparent swelling poly(vinyl ethers) 7a–b and 9a–b. Compounds 4a–b and 6a–b did not polymerize by radical initiators due to the steric hindrance. Polymers 7a–b and 9a–b were not soluble in common organic solvents such as acetone and DMSO due to crosslinking. Polymers 7a–b and 9a–b showed a thermal stability up to 300°C in TGA thermograms. Received: 1 December 1999/Revised version: 14 February 2000/Accepted: 16 February 2000     

Synthesis and properties of novel polyurethanes containing 2,4-dioxybenzylidenecyanoacetate group as a NLO-chromophore for electro-optic applications

Summary Methyl 2,4-bis-(2'-hydroxyethoxy)benzylidenecyanoacetate (3) was prepared by hydrolysis of methyl 2,4-bis-(2'-vinyloxyethoxy)benzylidenecyanoacetate (2). Diol 3 was condensed with 2,4-toluenediisocyanate, 3,3'-dimethoxy-4,4'-biphenylene-diisocyanate, and 1,6-hexamethylenediisocyanate to yield polyurethanes 4–6 containing the NLO-chromophore 2,4-dioxybenzylidenecyanoacetate. The resulting polyurethanes 4–6 were soluble in common organic solvents such as acetone and DMF. Polymers 4–6 showed a thermal stability up to 280°C in TGA thermograms with T _g values obtained from DSC thermograms in the range of 66–114°C. The SHG coefficients (d₃₃) of poled polymer films were around 7.8 × 10⁻⁹ esu. Received: 25 February 2002/ Revised version: 25 March 2002/ Accepted: 29 March 2002     

Using aluminium triflate as a co‐catalyst for the polymerization of o‐phenylenediamine and its derivatives

Aromatic diamine monomers, including o‐phenylenediamine (oPD), 4‐methyl‐o‐phenylenediamine (4Me‐oPD), 4,5‐dimethyl‐o‐phenylenediamine (dMe‐oPD) and 4‐(tert‐butyl)‐o‐phenylenediamine (tBu‐oPD), were polymerized by chemical oxidation using ammonium persulfate as an oxidant. Aluminium triflate (Al(OTf)₃) was also used for the first time as a co‐catalyst under various reaction conditions for the polymerization of oPD derivatives. The polymerization yield was improved when Al(OTf)₃ was introduced to the polymerization reaction for most polymers. The solubility of poly(4‐methyl‐o‐phenylenediamine) (P(4Me‐oPD)), poly(4,5‐dimethyl‐o‐phenylenediamine) (P(dMe‐oPD)) and poly(4‐(tert‐butyl)‐o‐phenylenediamine) (P(tBu‐oPD)) polymers was improved compared with the poly(o‐phenylenediamine) (P(oPD)) polymers in most common solvents. The homopolymers obtained were characterized by Fourier transform IR spectroscopy, UV?visible spectroscopy, ¹H and ¹³C NMR, wide‐angle X‐ray diffraction, DSC and TGA. The results showed that the yield, solubility and structure of the polymers are significantly dependent on the polymerization conditions. DSC measurements indicated that the polymers exhibited melting and crystallization transitions. The polymers also showed good thermal stability and decompose above 400 °C in nitrogen. © 2013 Society of Chemical Industry     

Synthesis and characterization of poly(ester‐ether‐imide)s derived from 5‐(4‐trimellitimidophenoxy)‐1‐trimellitimido naphthalene

A series of novel aromatic poly(ester‐ether‐imide)s with inherent viscosity values of 0.44–0.74 dL g^?1 were prepared by the diphenylchlorophosphate‐activated direct polycondensation of an imide ring‐containing diacid namely 5‐(4‐trimellitimidophenoxy)‐1‐trimellitimido naphthalene ( 1 ) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. Owing to comparison of the characterization data, an ester‐containing model compound ( 2 ) was also synthesized by the reaction of 1 with phenol. The model compound 2 and the resulted polymers were fully characterized by FT‐IR and NMR spectroscopy. The ultraviolet λ_max values of the poly(ester‐ether‐imide)s were also determined. The resulting polymers exhibited an excellent organosolubility in a variety of high polar solvents such as N,N‐dimethylacetamide, N,N‐dimethylformamide, dimethyl sulfoxide, and N‐methyl‐2‐pyrrolidone. They were soluble even in common less polar organic solvents such as pyridine, m‐cresol, and tetrahydrofuran on heating. Crystallinity of the polymers was estimated by means of wide‐angle X‐ray diffraction. The resulted polymers exhibited nearly an amorphous nature. From differential scanning calorimetry thermograms, the polymers showed glass‐transition temperatures between 221 and 245°C. Thermal behaviors of the obtained polymers were characterized by thermogravimetric analysis, and the 10% weight loss temperatures of the poly(ester‐ether‐imide)s were found to be over 410°C in nitrogen. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of novel poly(vinyl ether)s containing the oxybenzylidenemalononitrile group as a nonlinear optical chromophore,and their electro‐optic properties

2,4‐Di‐(2′,2′‐dicyanovinyl)‐1‐(2′‐vinyloxyethoxy)benzene and 2,4‐di‐(2′‐carbomethoxy‐2′‐cyanovinyl)‐1‐(2′‐vinyloxyethoxy)benzene were prepared by condensation of 4‐(2′‐vinyloxyethoxy)isophthaldehyde with malononitrile and methyl cyanoacetate, respectively. The two vinyl monomers were polymerized with boron trifluoride etherate as a cationic initiator to yield poly(vinyl ether)s containing two oxybenzylidenemalononitrile and oxybenzylidenecyanoacetate groups, which are effective chromophores for second‐order nonlinear optical applications. These polymers were soluble in common organic solvents such as acetone and dimethyl sulforide. They showed thermal stabilities up to 300 °C from thermogravimetric analysis (TGA), with differential scanning calorimeter (DSC) thermograms giving T_g values in the range 73–87 °C. The second harmonic generation (SHG) coefficients (d₃₃) of poled polymer films were around 1.8 × 10^?9 esu, and these polymers showed good long‐term thermal stability for 60 days at room temperature, which is acceptable for nonlinear optical (NLO) device applications. Copyright © 2004 Society of Chemical Industry     

Copolymers of aniline and o‐methoxyaniline. II. Thermoanalytical studies

A study on the thermal stability, thermodynamical parameters, especially relaxation transition temperature (T_g), and their change upon irreversible reactions (crosslinking, postpolymerization, decomposition, etc.) taking place on heating of the undoped homo‐ and copolymers of aniline and o‐methoxyaniline was performed by using differential scanning calorimetry. It was found that polyaniline and its oligomers might be responsible for the postpolymerization process observed on heating thermograms of the polymers in their emeraldine base form. It can be stated that the proceeding of this process appears to be a reason for the higher thermal stability of polyaniline when compared with poly(o‐methoxyaniline). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2729–2734, 2007     

Accelerated controlled radical polymerization of methacrylates

BACKGROUND: Nitroxide adducts 1,1‐ditertbutyl‐1‐(1‐methyl‐1‐cyanoethoxy)‐amine (AIBN/DBN), 1,1‐ditertbutyl‐1‐(benzoylperoxy)‐amine (BPO/DBN) and 2,2,6,6,‐tetramethyl‐4‐oxo‐1‐(1‐methyl‐1‐cyanoethoxy)‐piperidine (AIBN/4‐OXO‐TEMPO) were prepared and evaluated as stabilized unimolecular initiators for controlled radical polymerization of methacrylate monomers using sulfuric acid as an accelerating additive. Their effectiveness was evaluated from polymerization rates, molecular weight control and dispersity (D) of the polymers. Thermal stabilities of the polymers were also examined. The monomers used were methyl methacrylate, triethylene glycol dimethacrylate (TEGDMA) and ethoxylated bisphenol A dimethacrylate (EBPADMA). RESULTS: Polymerization was accomplished at 70 and 130 °C in 5 min to 144 h. The value of D of poly(methyl methacrylate) (PMMA) was 1.05–1.22. The glass transition temperature (T_g) for PMMA was 122–127 °C. The activity of the chain ends was established by chain extension and controlled polymerization was established by plotting M_n versus monomer conversion. First‐order kinetics in monomer consumption was established and an electron paramagnetic resonance study was conducted. Decomposition temperature (T_d) for PMMA was 360–380 °C, for poly(TEGDMA) was 300–380 °C and for poly(EBPADMA) was 360–440 °C. Photoinitiation without additive yielded no polymer. Thermal initiation by AIBN/4‐OXO‐TEMPO was the fastest. CONCLUSIONS: The initiators are applicable in low‐temperature additive‐enhanced controlled polymerization of methacylates and dimethacrylates, producing polymers with excellent attributes and a low value of D. Copyright © 2008 Society of Chemical Industry     

Synthesis and characterization of new thermally stable poly(ester‐imide)s derived from 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl and various aromatic dihydroxy compounds

A series of new alternating aromatic poly(ester‐imide)s were prepared by the polycondensation of the preformed imide ring‐containing diacids, 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl (2a) and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl (2b) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A model compound (3) was also prepared by the reaction of 2b with phenol, its synthesis permitting an optimization of polymerization conditions. Poly(ester‐imides) were fully characterized by FTIR, UV‐vis and NMR spectroscopy. Both biphenylene‐ and binaphthylene‐based poly(ester‐imide)s exhibited excellent solubility in common organic solvents such as tetrahydrofuran, m‐cresol, pyridine and dichloromethane. However, binaphthylene‐based poly(ester‐imide)s were more soluble than those of biphenylene‐based polymers in highly polar organic solvents, including N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide and dimethyl sulfoxide. From differential scanning calorimetry thermograms, the polymers showed glass‐transition temperatures between 261 and 315 °C. Thermal behaviour of the polymers obtained was characterized by thermogravimetric analysis, and the 10 % weight loss temperatures of the poly(ester‐imide)s was in the range 449–491 °C in nitrogen. Furthermore, crystallinity of the polymers was estimated by means of wide‐angle X‐ray diffraction. The resultant poly(ester‐imide)s exhibited nearly an amorphous nature, except poly(ester‐imide)s derived from hydroquinone and 4,4′‐dihydroxybiphenyl. In general, polymers containing binaphthyl units showed higher thermal stability but lower crystallinity than polymers containing biphenyl units. Copyright © 2005 Society of Chemical Industry     

Synthesis and properties of new aromatic poly(ester‐imide)s derived from 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl) pyridine and various dihydroxy compounds

A novel class of wholly aromatic poly(ester‐imide)s, having a biphenylene pendant group, with inherent viscosities of 0.32–0.49 dL g^?1 was prepared by the diphenylchlorophosphate‐activated direct polyesterification of the preformed imide‐ring‐containing diacid, 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl)pyridine (1) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A reference diacid, 2,6‐bis(trimellitimido)pyridine (2) without a biphenylene pendant group and two phenylene rings in the backbone, was also synthesized for comparison purposes. At first, with due attention to structural similarity and to compare the characterization data, a model compound (3) was synthesized by the reaction of compound 1 with two mole equivalents of phenol. Moreover, the optimum condition of polymerization reactions was obtained via a study of the model compound synthesis. All of the resulting polymers were characterized by Fourier transform infrared and ¹H NMR spectroscopy and elemental analysis. The ultraviolet λ_max values of the poly(ester‐imide)s were also determined. All of the resulting polymers exhibited excellent solubility in common organic solvents, such as pyridine, chloroform, tetrahydrofuran, and m‐cresol, as well as in polar organic solvents, such as N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide, and dimethyl sulfoxide. The crystalline nature of the polymers obtained was evaluated by means of wide‐angle X‐ray diffraction. The resulting poly(ester‐imide)s showed nearly an amorphous nature, except poly(ester‐imide) derived from 4,4′‐dihydroxy biphenyl. The glass transition temperatures (T_g) of the polymers determined by differential scanning calorimetry thermograms were in the range 298–342 °C. The 10% weight loss temperatures (T_10%) from thermogravimetric analysis curves were found to be in the range 433–471 °C in nitrogen. Films of the polymers were also prepared by casting the solutions. Copyright © 2006 Society of Chemical Industry     

Synthesis of poly(ethyl vinyl ethers) containing two dipolar electronic systems and their properties

Summary 5-Nitro-2-(2′-vinyloxyethoxy)benzylidenemalononitrile (2a), methyl 5-nitro-2-(2′-vinyloxyethoxy)benzylidenecyanoacetate (2b), 3-nitro-4-(2′-vinyloxyethoxy)benzylidenemalononitrile (4a), and methyl 3-nitro-4-(2′-vinyloxyethoxy)benzylidenecyanoacetate (4b) were prepared by the condensation of 5-nitro-2-(2′-vinyloxyethoxy)benzaldehyde (1) and 3-nitro-4-(2′-vinyloxyethoxy)benzaldehyde (3) with malononitrile or methyl cyanoacetate, respectively. Vinyl ether monomers 2a-b and 4a-b were polymerized with boron trifluoride etherate as a cationic initiator to yield poly(vinyl ethers) 5-6 having nitrooxybenzylidenemalononitrile and nitrooxycyanocinnamate, which is effective chromophore for second-order nonlinear optical applications. Polymers 5-6 were soluble in common organic solvents such as acetone and DMSO. T _g values of the resulting polymer were in the range of 70–81°C. Electrooptic coefficient (r₃₃) of the poled polymer films were in the range of 19–27 pm/V, which was improved by introducing of nitro group. Polymers 5–6 showed a thermal stability up to 300°C in TGA thermograms, which is acceptable for NLO device applications. Received: 24 November 1998/Revised version: 19 January 1999/Accepted: 29 January 1999     

Synthesis of highly crosslinked thermally stable poly(vinylethers) by free radical polymerization

Summary 2,4-Di-(2'-vinyloxyethoxy)benzylidenemalononitrile (2a), methyl 2,4-di-(2'-vinyloxyethoxy)benzylidenecyanoacetate (2b), 3,4-di-(2'-vinyloxyethoxy)benzylidenemalononitrile (4a), and methyl 3,4-di-(2'-vinyloxyethoxy)benzylidenecyanoacetate (4b) were prepared by the condensation of 2,4-di-(2'-vinyloxyethoxy)benzaldehyde (1) and 3,4-di-(2'-vinyloxyethoxy)benzaldehyde (3) with malononitrile or methyl cyanoacetate, respectively. Trifunctional vinyl ether monomers 2 and 4 were polymerized readily by free radical initiators to give optically transparent swelling poly(vinylethers) 5 and 6. Polymers 5 and 6 were not soluble in common organic solvents such as acetone and DMSO due to crosslinking. Polymers 5 and 6 showed a thermal stability up to 300°C in DSC thermograms. Received: 24 February 1998/Revised version: 7 April 1998/Accepted: 7 April 1998     

Organosoluble and light‐colored fluorinated polyimides based on 1,1‐bis[4‐(4‐amino‐2‐trifluoromethylphenoxy)phenyl]‐1‐phenylethane and various aromatic dianhydrides

To investigate the CF₃ group affecting the coloration and solubility of polyimides (PI), a novel fluorinated diamine 1,1‐bis[4‐(4‐amino‐2‐ trifluoromethylphenoxy)phenyl]‐1‐phenylethane (2) was prepared from 1,1‐ bis(4‐hydrophenyl)‐1‐phenylethan and 2‐chloro‐5‐nitrobenzotrifluoride. A series of light‐colored and soluble PI 5 were synthesized from 2 and various aromatic dianhydrides 3a–f using a standard two‐stage process with thermal 5a– f(H) and chemical 5a–f(C) imidization of poly(amic acid). The 5 series had inherent viscosities ranging from 0.55 to 0.98 dL/g. Most of 5a–f(H) were soluble in amide‐type solvents, such as N‐methyl‐2‐pyrrolidone (NMP), N,N‐ dimethylacetamide (DMAc), and N,N‐dimethylformamide (DMF), and even soluble in less polar solvents, such as m‐Cresol, Py, Dioxane, THF, and CH₂Cl₂, and the 5(C) series was soluble in all solvents. The GPC data of the 5a–f(C) indicated that the Mn and Mw values were in the range of 5.5–8.7 × 10⁴ and 8.5–10.6 × 10⁴, respectively, and the polydispersity index (PDI) Mw /Mn values were 1.2–1.5. The PI 5 series had excellent mechanical properties. The glass transition temperatures of the 5 series were in the range of 232–276°C, and the 10% weight loss temperatures were at 505–548 °C in nitrogen and 508–532 °C in air, respectively. They left more than 56% char yield at 800°C in nitrogen. These films had cutoff wavelengths between 356.5–411.5 nm, the b* values ranged from 5.0–71.1, the dielectric constants, were 3.11–3.43 (1MHz) and the moisture absorptions were in the range of 011–0.40%. Comparing 5 containing the analogous PI 6 series based on 1,1‐bis[4‐(4‐aminophenoxy)phenyl]‐1‐ phenylethane (BAPPE), the 5 series with the CF₃ group showed lower color intensity, dielectric constants, and better solubility. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2399–2412, 2005     

Structure–property relationship of pH‐sensitive (PCL)2(PDEA‐b‐PPEGMA)2 micelles: Experiment and DPD simulation

The experiment and dissipative particle dynamics simulation were carried out on four polymers with different block ratios for the investigation of the structure–property relationship of (poly(ε‐caprolactone)₂‐[poly(2‐(diethylamino)ethyl methacrylate)‐b‐poly(poly(ethylene glycol) methyl ether methacrylate)]₂ [(PCL)₂(PDEA‐b‐PPEGMA)₂] micelles. The miktoarm star polymers assembled into spherical micelles composed of PCL core, pH‐sensitive PDEA mesosphere and poly (ethylene glycol) methyl ether methacrylate (PPEGMA) shell. When decreasing pH from 7.4 to 5.0, the hydrodynamic diameter and transmittance of (PCL)₂(PDEA‐b‐PPEGMA)₂ micelles increased along with globule‐uneven‐extended conformational transitions, owing to the protonation of tertiary amine groups of DEA at lower pH conditions. Doxorubicin (DOX) was mainly loaded in the pH‐sensitive layer, and more DOX were loaded in the core when increasing drug concentrations. The in vitro DOX release from the micelles was significantly accelerated by decreasing pH from 7.4 to 5.0. The results demonstrated that the pH‐sensitive micelles could be used as an efficient carrier for hydrophobic anticancer drugs, achieving controlled and sustained drug release. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3634–3646, 2014     

Characterization of acrylamide polymers for enhanced oil recovery

Four different copolymers, of acrylamide and acrylic acid, acrylamide and 2‐acrylamido‐2‐methyl propane sulfonic acid, N,N‐dimethylacrylamide and acrylic acid, and N,N‐dimethylacrylamide and 2‐acrylamido‐2‐methyl propane sulfonic acid (sodium salts), were prepared. The copolymers were characterized by their intrinsic viscosities and monomer ratios and with IR, ¹H‐NMR, and X‐ray diffraction (XRD) spectroscopy. No crystallinity was observed by differential thermal analysis, and this was well supported by XRD. All the polymers showed low decomposition temperatures. A number of decomposition temperatures were observed in differential thermogravimetry thermograms because of the elimination of gases such as CO₂, SO₂, CO, and NH₃. The replacement of the acrylate group with a sulfonate group produced polymers that were more compatible with brine, whereas the replacement of acrylamide with a more hydrophobic group such as N,N‐dimethylacrylamide produced a more shear‐resistant polymer. A N,N‐dimethylacrylamide‐co‐sodium‐2‐acrylamido‐2‐methyl propane sulfonate copolymer was better with respect to thermal stability when the polymer solution was aged at 120°C for a period of 1 month. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1869–1878, 2003     

Influence of the comonomers (styrene and methyl acrylate) on the rate of photocrosslinking of 4‐{[‐3‐(4‐hydroxybenzylidene)‐2‐oxocyclohexylidene]methyl}‐ phenyl acrylate

[2,6‐Bis(4‐hydroxybenzylidene)cyclohexanone] (HBC) was prepared by reacting cyclohexanone and p‐hydroxybenzaldehyde in the presence of acid catalyst. Acrylated derivative of HBC, 4‐{[‐3‐(4‐hydroxybenzylidene)‐2‐oxocyclohexylidene]methyl}phenyl acrylate (HBA), was prepared by reacting HBC with acryloyl chloride in the presence of triethylamine. Copolymers of HBA with styrene (S) and methyl acrylate (MA) of different feed compositions were carried out by solution polymerization technique by using benzoyl peroxide (BPO) under nitrogen atmosphere. All monomers and polymers were characterized by using IR and NMR techniques. Reactivity ratios of the monomers present in the polymer chain were evolved by using Finnman–Ross (FR), Kelen–Tudos (KT), and extended Kelen–Tudos (ex‐KT) methods. Average values of reactivity were achieved by the following three methods: r₁ (S) = 2.36 ± 0.45 and r₂ (HBA) = 0.8 ± 0.31 for poly(S‐co‐HBA); r₁ = 1.62 ± 0.06 (MA); and r₂ = 0.12 ± 0.07 (HBA) for poly(MA‐co‐HBA). The photocrosslinking property of the polymers was done by using UV absorption spectroscopic technique. The rate of photocrosslinking was enhanced compared to that of the homopolymers, when the HBA was copolymerized with S and MA. Thermal stability and molecular weights (M_w and M_n) were determined for the polymer samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2494–2503, 2004     

Synthesis and thermotropic liquid‐crystalline behavior of novel main‐chain poly(aryl ether ketones)

Novel aromatic poly(ether ketones) containing bulky lateral groups were synthesized via nucleophilic substitution reactions of 4,4′‐biphenol and (4‐chloro‐3‐trifluoromethyl)phenylhydroquinone (CF‐PH) with 1,4‐bis(p‐fluorobenzoyl)benzene. The copolymers were characterized by differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction, and polarized light microscopy observation. Thermotropic liquid‐crystalline behavior was observed in the copolymers containing 40, 50, 60, and 70 mol % CF‐PH. The crystalline–liquid‐crystalline transition [melting temperature (T_m)] and the liquid‐crystalline–isotropic phase transition appeared in the DSC thermograms, whereas the biphenol‐based homopolymer had only a melting transition. The novel poly(aryl ether ketones) had glass‐transition temperatures that ranged from 143 to 151°C and lower T_m's that ranged from 279 to 291°C, due to the copolymerization. The polymers showed high thermal stability, and some exhibited a large range in mesophase stability. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1347–1350, 2003