Thermosensitive self‐assembly micelles from A2BA2‐type poly(N‐isopropyl acrylamide)2‐b‐Poly(lactic acid)‐b‐Poly(N‐isopropyl acrylamide)2 four‐armed star block copolymers and their applications as drug carriers

A novel A₂BA₂‐type thermosensitive four‐armed star block copolymer, poly(N‐isopropyl acrylamide)₂‐b‐poly(lactic acid)‐b‐poly(N‐isopropyl acrylamide)₂, was synthesized by atom transfer radical polymerization and characterized by ¹H‐NMR, Fourier transform infrared spectroscopy, and size exclusion chromatography. The copolymers can self‐assemble into nanoscale spherical core–shell micelles. Dynamic light scattering, surface tension, and ultraviolet–visible determination revealed that the micelles had hydrodynamic diameters (D_h) below 200 nm, critical micelle concentrations from 50 to 55 mg/L, ζ potentials from ?7 to ?19 mV, and cloud points (CPs) of 34–36°C, depending on the [Monomer]/[Macroinitiator] ratios. The CPs and ζ potential absolute values were slightly decreased in simulated physiological media, whereas D_h increased somewhat. The hydrophobic camptothecin (CPT) was entrapped in polymer micelles to investigate the thermo‐induced drug release. The stability of the CPT‐loaded micelles was evaluated by changes in the CPT contents loaded in the micelles and micellar sizes. The MTT cell viability was used to validate the biocompatibility of the developed copolymer micelle aggregates. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4137–4146, 2013     

Competitive removal of heavy metal ions by cellulose graft copolymers

The effect of composition of graft chains of four types cellulose graft copolymers on the competitive removal of Pb²⁺, Cu²⁺, and Cd²⁺ ions from aqueous solution was investigated. The copolymers used were (1) cellulose‐g‐polyacrylic acid (cellulose‐g‐pAA) with grafting percentages of 7, 18, and 30%; (2) cellulose‐g‐p(AA–NMBA) prepared by grafting of AA onto cellulose in the presence of crosslinking agent of N,N′‐methylene bisacrylamide (NMBA); (3) cellulose‐g‐p(AA–AASO₃H) prepared by grafting of a monomer mixture of acrylic acid (AA) and 2‐acrylamido‐2‐methyl propane sulphonic acid (AASO₃H) containing 10% (in mole) AASO₃H; and (4) cellulose‐g‐pAASO₃H obtained by grafting of AASO₃H onto cellulose. The concentrations of ions which were kept constant at 4 mmol/L in an aqueous solution of pH 4.5 were equal. Metal ion removal capacities and removal percentages of the copolymers was determined. Metal ion removal capacity of cellulose‐g‐pAA did not change with the increase in grafting percentages of the copolymer and determined to be 0.27 mmol metal ion/g_copolymer. Although the metal removal rate of cellulose‐g‐p(AA–NMBA) copolymer was lower than that of cellulose‐g‐pAA, removal capacities of both copolymers were the same which was equal to 0.24 mmol metal ion/g_copolymer. Cellulose did not remove any ion under the same conditions. In addition, cellulose‐g‐pAASO₃H removed practically no ion from the aqueous solution (0.02 mmol metal ion/g_copolymer). The presence of AASO₃H in the graft chains of cellulose‐g‐p(AA–AASO₃H) created a synergistic effect with respect to metal removal and led to a slight increase in metal ion adsorption capability in comparison to that of cellulose‐g‐pAA. All types of cellulose copolymers were found to be selective for the removal of Pb²⁺ over Cu²⁺ and Cd²⁺. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2034–2039, 2003     

Yellow‐Emitting Y3Si6N11: Ce3+ Phosphors for White Light–Emitting Diodes (LEDs)

A novel Y_3?xSi₆N₁₁: xCe³⁺ yellow phosphor was synthesized using the carbothermal reduction and nitridition method at 1550°C for 16 h in this letter. Photoluminescence spectra indicated that the phosphor showed broad excitation spectrum and had strong absorption in range of 350–450 nm. It also gave a broad emission band (Full width at half maximum = 153 nm) centered at 575 nm under 425‐nm excitation. With increasing Ce³⁺ concentration, the strongest emission intensity was obtained at 5 mol% Ce³⁺ doping amount and a systematic redshift was observed as the Ce³⁺ concentration increased. The results indicate that this novel yellow phosphor is a promising candidate for using in blue‐chip‐excited white light–emitting diodes (LEDs).     

Optical Property of Dy3+‐and Ce3+‐Doped Si–B–Na–Sr Glasses

Novel Dy³⁺ and Ce³⁺ doped Si–B–Na–Sr (SBNS) glasses were synthesized by melt‐quenching technique. Excited by 327 nm, the 0.5Dy³⁺‐and 0.5Ce³⁺‐doped SBNS exhibits white emission with Commission Internationale de L'Eclairage coordinates of (0.308, 0.280). Basic optical characterizations have been performed by measuring the absorption and emission spectra and calculating Judd–Ofelt intensity parameters, radiative probability, luminescence branching ratio, cross sections, and effective bandwidth. The Judd–Ofelt parameters Ω₂, Ω₄, and Ω₆ indicate a high asymmetrical environment and covalent environment in the optical glass. The emission color of Ce³⁺ and Dy³⁺ codoped transparent glass can be tuned from blue to white through energy transfer from Ce³⁺ to Dy³⁺ ions. The resulting glass may have potential application in white‐light‐emitting source.     

Luminescence Properties and Energy Transfer of Ce3+,Tb3+‐Coactivatedβ‐SiAlON Phosphors

Using the solid‐state reaction method, Ce³⁺,Tb³⁺‐coactivated Si₅AlON₇ (Si_6?zAl_zO_zN_8?z, z = 1) phosphors were successfully synthesized. The obtained phosphors exhibit high absorption and strong excitation bands in the wavelength range of 240–440 nm, matching well with the light emitting‐diode (LED) chip. The ET from Ce³⁺ to Tb³⁺ ions in Si₅AlON₇:Ce³⁺,Tb³⁺ has been studied and demonstrated by the luminescence spectra and decay curves. Moreover, the phosphors show tunable emissions from blue to green by tuning the relative ratio of the Ce³⁺ to Tb³⁺ ions. Thermal quenching properties of Si₅AlON₇:Ce³⁺,Tb³⁺ had also been investigated and the quenching temperature is ~190°C. These results show that Si₅AlON₇:Ce³⁺,Tb³⁺ could be a promising candidate for a single‐phased color‐tunable phosphor applied in UV‐chip pumped LEDs.     

Graft copolymerization of acrylamide–methylacrylate comonomers onto cellulose using ceric ammonium nitrate

The graft copolymerization of acrylamide–methylacrylate comonomers was carried out using ceric ammonium nitrate as initiator in the presence of nitric acid at 25 ± 1°C. The effects of feed molarity, feed composition, reaction time, and temperature on graft yield (%G) and other grafting parameters were investigated. The determination of rate of ceric (IV) ions disappearance as a function of feed molarity and reaction time was useful in the determination of the rate of ceric (IV) ions consumption during graft copolymerization. The graft yield (%G) in the presence of acrylamide increases because of the synergistic effect of acrylamide comonomer. The composition of the grafted chains (F_AAm) varies on varying the feed composition and reaction temperature but is almost constant during feed molarity variation. The Mayo and Lewis method was used to determine the reactivity ratios of acrylamide (r₁) and methylacrylate (r₂), which are 0.65 and 1.07, respectively. The product of reactivity ratio (r₁ r₂) is less then unity; hence, an alternate arrangement of comonomer blocks in the grafted copolymer chain is proposed. The rate of graft copolymerization of comonomers onto cellulose is second power to the concentration of comonomers and square root to the concentration of ceric ammonium nitrate. Suitable reaction steps for graft copolymerization of comonomers onto cellulose are proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2631–2642, 2002     

Removal of concentrated heavy metal ions from aqueous solutions using polymers with enriched amidoxime groups

Particulate and fibrous adsorbents with enriched amidoxime groups were synthesized by using a novel monomer N,N′‐dipropionitrile acrylamide. The adsorption properties of amidoximated poly(N,N′‐dipropionitrile acrylamide) [poly(DPAAm)] particles and a nonwoven fabric grafted with the same for UO₂²⁺, Pb²⁺, Cu²⁺, and Co²⁺ at high concentrations were investigated by batch process. Metal ion adsorption studies were conducted from metal ion solutions with different initial concentrations (100–1500 ppm). It was shown that particulated amidoximated poly(DPAAm) has higher adsorption capacity than amidoximated nonwoven fabrics for all metal ions, especially for uranyl ions. The results of the adsorption studies showed that the interaction between UO₂²⁺ and amidoximated groups agree with the Langmuir‐type isotherm. From the Langmuir equation, the adsorption capacities were found as 400 mg UO₂²⁺/g dry amidoximated poly(DPAAm) and 250 mg UO₂²⁺/g dry amidoximated graft polymer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1705–1710, 2004     

Electrochemical behaviors of polyaniline–poly(styrene‐sulfonic acid) complexes and related films

This research focuses on the syntheses of polyaniline with poly(styrenesulfonic acid) and their electrochemical behavior, including absorbance behavior and electrochemical response time of polyaniline‐poly(styrenesulfonic acid) [PANI–PSSA]. The complexes PANI–PSSA were prepared by electrochemical polymerization of monomer (aniline) with PSSA, using indium‐tin oxide (ITO) as working electrode in 1M HCl solution. Polyaniline (PANI), poly(o‐phenetidine)–poly(styrenesulfonic acid) [POP–PSSA], and poly(2‐ethylaniline)–poly(styrenesulfonic acid) [P2E‐PSSA] also were prepared by electrochemical polymerization and to be the reference samples. The products were characterized by IR, VIS, EPR, water solubility, elemental analysis, conductivity, SEM, and TEM. IR spectral studies shows that the structure of PANI–PSSA complexes is similar to that of polyaniline. EPR and visible spectra indicate the formation of polarons. The morphology of the blend were investigated by SEM and TEM, which indicate the conducting component and electrically conductive property of the polymer complexes. Elemental analysis results show that PANI–PSSA has a nitrogen to sulfur ratio (N/S) of 38%, lower than that for POP–PSSA (52%) and P2E–PSSA (41%). Conductivity of the complexes are around 10^?2 S/cm, solubility of PANI–PSSA in water is 3.1 g/L. The UV‐Vis. absorbance spectra of the hybrid organic/inorganic complementary electro‐chromic device (ECD), comprising a polyaniline–poly(styrenesulfonic acid) [PANI–PSSA] complexes and tungsten oxide (WO₃) thin film coupled in combination with a polymer electrolyte poly(2‐acrylamido‐2‐methyl‐propane‐sulfonic acid) [PAMPSA]. PANI–PSSA microstructure surface images have been studied by AFM. By applying a potential of ～3.0 V across the two external ITO contacts, we are able to modulate the light absorption also in the UV‐Vis region (200–900 nm) wavelength region. For example, the absorption changes from 1.20 to 0.6 at 720 nm. The complexes PANI–PSSA, POP–PSSA, and P2E–PSSA were prepared by electrochemical polymerization of monomer (aniline, o‐phenetidine, or 2‐ethylaniline) with poly(styrenesulfonic acid), using ITO as working electrode in 1M HCl solution, respectively. UV‐Vis spectra measurements shows the evidences for the dopped polyaniline system to be a highly electrochemical response time, recorded at the temperature 298 K, and the results were further analyzed on the basis of the color‐ discolor model, which is a typical of protontation systems. Under the reaction time (3 s) and monomer (aniline, o‐phenetidine, 2‐ethylaniline) concentration (0.6M) with PSSA (0.15M), the best electrochemical color and discolor time of the PANI–PSSA is slower than POP–PSSA complexes (125/125 ms; thickness, 3.00 μm) and P2E–PSSA complexes. Under the same thickness (10 μm), the best electrochemical color and discolor time of the PANI–PSSA complexes is 1500/750 ms, that is much slower than P2E–PSSA complexes (750/500 ms) and POP–PSSA complexes (500/250 ms). In film growing rate, the PANI–PSSA complexes (0.54 μm/s) are slower than P2E–PSSA complexes (0.79 μm/s) and POP–PSSA complexes (1.00 μm/s), it can be attributed to the substituted polyaniline that presence of electro‐donating (? OC₂H₅ or ? C₂H₅₎ group present in aniline monomer. The EPR spectra of the samples were recorded both at 298 K and 77 K, and were further analyzed on the basis of the polaron–bipolaron model. The narrower line‐width of the substituted polyaniline complexes arises due to polarons; i.e., it is proposed that charge transport take place through both polarons and bipolarons, compared to their salts can be attributed to the lower degree of structural disorder, the oxygen absorption on the polymeric molecular complexes, and due to presence of electro‐donating (? OC₂H₅ or ? C₂H₅) group present in aniline monomer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:4023–4044, 2006     

Structure and Photoluminescence of A Blue‐Green‐Emitting Phosphor for Near‐UV White LEDs

A series of phosphors Ca_12(0.97?x)Al₁₄O₃₂F₂: 0.03Ce³⁺, xTb³⁺ have been prepared by a hightemperature solid‐state reaction using boric acid as flux. These oxyfluorides crystallize in cubic structure, space group. Under the near ultraviolet excitation within wavelength range 310–390 nm, Ca_12(0.97?x)Al₁₄O₃₂F₂: 0.03Ce³⁺, xTb³⁺ phosphors exhibit an intense emission covering a broad band of 370–500 nm derived from the 5d→4f transitions of Ce³⁺ and a characteristic emission at 544 nm of Tb³⁺. The emission can be tuned from blue to green by altering the relative ratio of Ce³⁺ to Tb³⁺ in the composition. The energy‐transfer mechanism from Ce³⁺ to Tb³⁺ is investigated based on the site occupancy of the luminescence center in the crystal structure of the Ca₁₂Al₁₄O₃₂F₂ host. More importantly, when a certain amount of boric acid is added as flux in the synthesis, the fluorescence intensity of the phosphors increases about 65%. Because of its broad excitation and efficiently tunable blue to green luminescence, the Ca_12(0.97?x)Al₁₄O₃₂F₂: 0.03Ce³⁺, xTb³⁺ phosphors may find promising application as a near UV‐convertible phosphor for white‐light‐emitting diodes.     

Synthesis,Structure and Electrical Properties of Mo‐doped CeO2–Materials for SOFCs

In this paper, we report the synthesis, structure and electrical conductivity of Mo‐doped compounds with a nominal chemical formula of Ce_1–xMo_xO_2+δ (x = 0.05, 0.07, 0.1) (CMO). The formation of fluorite‐like structure with a small amount of Ce₈Mo₁₂O₄₉ impurity (JCPDS Card No. 31‐0330) was confirmed using a powder X‐ray diffraction (PXRD). The fluoride‐type structure was retained under wet H₂ and CH₄ atmospheres at 700 and 800 °C, while diffraction peaks due to metal Mo were observed in dry H₂ under the same condition. AC impedance measurements showed that the total conductivity increases with increasing Mo content in CMO, and among the investigated samples, Ce_0.9Mo_0.1O_2+δ exhibited the highest electrical conductivity with a value of 2.8 × 10^–4 and 5.08 × 10^–2 S cm^–1 at 550 °C in air and wet H₂, respectively. The electrical conductivity was found to be nearly the same, especially at high temperatures, in air, O₂ and N₂. Chemical compatibility of Ce_0.9Mo_0.1O_2+δ with 10 mol‐% Y₂O₃ stabilised ZrO₂ (YSZ) and Ce_0.9Gd_0.1O_1.95 (CGO) oxide ion electrolytes in wet H₂ was evaluated at 800–1,000 °C, using PXRD and EDX analyses. PXRD showed that CMO was found to react with YSZ electrolyte at 1,000 °C. The area specific polarisation resistance (ASPR) of Ce_0.9Mo_0.1O_2+δ on YSZ was found to be 8.58 ohm cm² at 800 °C in wet H₂.     

Photoluminescence Properties of Color‐Tunable Ca3La6(SiO4)6: Ce3+, Tb3+ Phosphors

A series of newly developed color‐tunable Ca₃La₆(SiO₄)₆: Ce³⁺, Tb³⁺ phosphors were successfully prepared in this study. The crystal structures of the prepared phosphors were revealed to be hexagonal with space group P6₃/m, and the lattice parameters were evaluated via utilizing the Rietveld refinement method. Upon excitation at 288 nm, the emission spectra of Ce³⁺and Tb³⁺ ions co‐doped Ca₃La₆(SiO₄)₆ phosphors included a blue emission band and several emission lines. The blue emission band with a peak at 420 nm originated in the f–d transitions of Ce³⁺ ions, and the emission lines in the range of 450–650 nm were assigned to the ⁵D₄ → ⁷F_J (J = 6, 5, 4, 3) transitions of Tb³⁺ ions. Increasing the doping content of Tb³⁺ ions considerably strengthened Tb³⁺ emission and reduced Ce³⁺ emission owing to the energy transfer from Ce³⁺ to Tb³⁺ ions. The mechanism of the energy transfer was confirmed to be a dipole–dipole interaction. The effective energy transfer from Ce³⁺ to Tb³⁺ ions caused a color shift from purplish‐blue to yellowish‐green. Color‐tunable Ca₃La₆(SiO₄)₆: Ce³⁺, Tb³⁺ phosphors have the potential to be utilized in light‐emitting diodes with proper modulation of the amount of Tb³⁺ ions.     

Selective removal of 1,2‐propanediol and 1,2‐butanediol from bio‐ethylene glycol by catalytic reaction

Ethylene glycol (EG), synthesized from biomass, frequently contains refractory 1,2‐propanediol (PDO) and 1,2‐butanediol (BDO). Selective removal of PDO and BDO was realized herein by catalytic dehydration to form volatile aldehydes, ketones, and acetals. Various acidic and basic catalysts were screened under a range of conditions for the conversion of a mixture containing 73 wt % EG, 20 wt % PDO, and 7 wt % BDO. Over H‐Beta 26 zeolite, the most selective catalyst among tested, PDO and BDO conversions reached 99.1 and 99.3%, respectively, after 4 h reaction at 453 K, with separation factors over 2. The activation energies for EG, PDO, and BDO dehydration were ca. 99.3, 69.9, and 54.0 kJ/mol, respectively, accounting for the high reactivity of PDO and BDO. The dehydration largely proceeded in the micropores of H‐Beta and depended on the number of strong Brønsted acid sites, but excessively strong acid sites enhanced the polymerization of EG. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4032–4042, 2017     

Optical Investigation of Ce3+‐Activated Borogermanate Glass Induced by Substitution of BaF2 for BaO

Transparent and colorless CeO₂‐activated borogermanate glasses, with the nominal molar composition of 25B₂O₃–40GeO₂–14Gd₂O₃–1CeO₂–(20?x) BaO–xBaF₂ (x = 0, 2.5, 5, 10, 15 and 20), were synthesized by a melt‐quenching method in air. Their optical investigation on the transmittance, photoluminescence (excitation and emission spectra), the luminescence decay curves, as well as the temperature‐dependent Ce³⁺ emission are studied systematically with the gradual substitution of BaF₂ for BaO. The room‐temperature photoluminescence results reveal that the emission intensity can be improved by about 2.5 times with the full substitution of BaF₂ for BaO. The blue shift of the cut‐off edge, excitation and emission spectra of Ce³⁺‐activated borogermanate glass, and the emission intensity of Ce³⁺ ions as a function of temperature range in 80–500 K are also discussed.     

Li2SrSiO4:Ce3+, Pr3+ Phosphor with Blue,Red, and Near‐Infrared Emissions Used for Plant Growth LED

Ce³⁺/Pr³⁺ codoped Li₂SrSiO₄ (LSS) phosphors with blue, red, and near‐infrared (NIR) tri‐emission have been prepared via a high‐temperature solid‐state reaction method. Under the excitation of 200 to 400 nm near‐ultraviolet (n‐UV), the photoluminescence (PL) spectra of phosphors are composed of visible and NIR two parts. The former exhibits blue and red emission bands centered at around 428 nm from 5d–4f transition of Ce³⁺ and 611 nm from ¹D₂ → ³H₄ transition of Pr³⁺, those overlap with photosynthesis action spectra of plants and absorption spectra of chlorophylls and carotenoids. While the later presents a broad NIR emission band peaking near 1039 nm caused by the ¹G₄ → ³H₄ of Pr³⁺, matching with the absorption of bacteriochlorophyll. Their emission intensity ratios (B: R: NIR) could be tuned by altering the relative ratios of Ce³⁺ and Pr³⁺ concentration in the phosphors to meet the requirements of multifarious plants and bacteria. The efficient energy transfer from Ce³⁺ to Pr³⁺ takes place in the LSS host, which ascribed to an exchange interaction according to PL spectra and decay curves of phosphors. Results suggest that the present LSS: Ce³⁺, Pr³⁺ phosphors have great potential applications in plant growth n‐UV LED.     

Synthesis and antimicrobial activity of biocidal polymer–montmorillonite nanocomposites

The bioactive agents p‐hydroxymethylbenzoate, 2,4‐dihydroxymethylbenzoate and methylsalicylate were reacted with polyoxyalkylene (D_230–2000)–montmorillonite (MMT) intercalated nanocomposites. D_230–2000–MMT were prepared by an ion exchange process of Na‐MMT and? NH₃⁺ groups in polyoxyalkylene amine hydrochloride of three different molecular masses (D₂₃₀, D₄₀₀ and D₂₀₀₀). The results of X‐ray analysis and transmission electron microscopy show that D₂₀₀₀–MMT/p‐hydroxymethylbenzoate is an exfoliated nanocomposite, whereas in D₂₃₀–MMT/p‐hydroxymethylbenzoate, D₂₃₀–MMT/2,4‐dihydroxymethylbenzoate, D₂₃₀–MMT/methylsalicylate and D₄₀₀–MMT/p‐hydroxymethylbenzoate, having lower molecular mass and polymer loading, the MMT rearranges in an intercalated and flocculated structure. The amount of intercalated polymer and interaction between polymer and layered silicate were determined using thermogravimetric analysis and Infrared spectroscopy. The antimicrobial activities of the nanocomposites were qualitatively and quantitatively assessed by agar diffusion tests and minimal inhibitory concentration values against a Gram‐negative bacterium (Escherichia coli NCIM 2065), a Gram‐positive bacterium (Bacillus subtilis ATCC) and fungi (Candida albicans SC5314 and Cryptococcus neoformans). The D₂₀₀₀–MMT/p‐hydroxymethylbenzoate nanocomposite strongly inhibits the growth of all the micro‐organisms tested. The diameter of the inhibition zone varies according to the type of micro‐organism tested. The effect of nanocomposite concentration on morphology, respiration and release of calcium, potassium and sodium ions of the test micro‐organisms was examined. Copyright © 2011 Society of Chemical Industry     

Improvement of Luminescence Properties of Blue‐to‐Red Emitting NaCaBO3: Ce3+, Mn2+ Phosphor Prepared by Sol–Gel Method

Color‐tunable phosphors NaCaBO₃: Ce³⁺, Mn²⁺ were synthesized by sol–gel (SG) and solid state (SS) method. SEM observation indicated that the microstructure of phosphor (SG) consisted of regular fine grains with an average size of about 5 μm. NaCaBO₃: Ce³⁺, Mn²⁺ showed two emission bands: one at 425 nm for Ce³⁺ and another at 610 nm for Mn²⁺. NaCaBO₃: Ce³⁺, Mn²⁺ (SG) exhibit higher energy‐transfer efficiency (90%) and higher Mn²⁺ quantum efficiency (80%) than SS samples, due to smooth surface, narrow size distribution, and improved homogeneity of sensitizer/activator ions. NaCaBO₃: Ce³⁺, Mn²⁺ exhibits blue‐to‐red tunable color by changing Ce³⁺/Mn²⁺ ratio.     

Preparation,characteristics, and flocculation behavior of modified palygorskite–polyacrylamide ionic hybrids

A novel inorganic–organic hybrid with modified palygorskite (MPGS) and acrylamide was prepared with a heterogeneous redox initiator system composed of a reductive agent (MPGS) together with an oxidant (Ce⁴⁺). The MPGS–polyacrylamide (PAM) hybrids were characterized by X‐ray diffraction, ¹H‐NMR, Fourier transform infrared spectroscopy, conductometry, viscometry, and size exclusion chromatography. The MPGS–PAM hybrid could be a starlike and ionic bond hybrid. The ionization behavior of the MPGS–PAM hybrid in deionized water depended strongly on its coil dimension and the palygorskite content in the hybrid. The flocculation performance of the MPGS–PAM hybrid in a kaolin suspension was also related to its intrinsic viscosity and the palygorskite content and was better than that of PAM, except for that of the MPGS–PAM hybrid with a high palygorskite content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1494–1500, 2006     

Synthesis and thermal characterization of random poly(butylene terephthalate‐co‐2‐methyl‐ethylene terephthalate) copolyesters

Poly(butylene terephthalate‐co‐2‐methyl‐ethylene terephthalate) (PBT/MET) was synthesized by incorporating 1,2‐propandiol(1,2‐PDO) into PBT chains. The molar composition and chemical structure of PBT/MET copolyesters were confirmed by means of FT‐IR and ¹H‐NMR. To investigate the effect of 1,2‐PDO on the thermal properties of PBT/MET copolyesters, the copolymerizations were carried out by varying various contents of MET units, and the prepared materials were evaluated by differential scanning calorimetry and thermogravimetric analysis. Results suggested that with the increase of the content of 1,2‐PDO, the amount of crystallinity and the melting temperature decline, while the glass transition temperature increases and the copolyesters become more transparent and brittle with respect to PBT homopolymer. In addition, the T_g‐composition and T_m‐composition data are well subjected to the Wood equation and Flory's equation, respectively. All these copolyesters are found to consist of the general trend displayed by copolymers reported elsewhere. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of ultrasonic irradiation on ceric‐salt‐initiated grafting of methyl methacrylate onto regenerated cellulose film

Effect of ultrasonic irradiation on ceric salt (Ce⁴⁺)‐initiated grafting of methyl methacrylate (MMA) on regenerated cellulose film (thickness = 20 μm) was investigated under an air atmosphere in water solvent at 60°C. The grafting system with the ultrasonic irradiation was characterized by higher percentage of grafting and graft efficiency than the system without the irradiation. Reaction of cellulose with Ce⁴⁺ was also accelerated by the ultrasonic irradiation. No accelerating effect of grafting due to the ultrasonic irradiation was observed for the system under reduced pressure of 5 torr. The effect of the ultrasonic irradiation on the average molecular weight of MMA‐grafted chains was also studied. Moreover, the surface layer of the resulting grafted films was examined by attenuated total reflection–infrared (ATR–IR) measurement and scanning electron microscopy (SEM) observation. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 251–258, 1999     

One‐step synthesis of triarm block copolymers via simultaneous reversible‐addition fragmentation chain transfer and ring‐opening polymerization

One‐step synthesis of star copolymers by reversible addition–fragmentation chain transfer (RAFT) and ring‐opening polymerization (ROP) by using a novel dual initiator is reported. Triarm block copolymers comprising one polystyrene (or polyacrylamide) arm and two poly(β‐butyrolactone) arms were synthesized in one‐step by simultaneous RAFT polymerization of styrene (St) (or acrylamide, designated as AAm) and ROP of β‐butyrolactone (BL) in the presence of a novel trifunctional initiator, 1,2‐propanediol ethyl xanthogenate (RAFT‐ROP agent). This dual initiator was obtained through the reaction of 3‐chloro‐1,2‐propanediol with the potassium salt of ethyl xanthogenate. The principal parameters such as monomer concentration, initiator concentration, and polymerization time that affect the one‐step polymerization reaction were evaluated. The characterization of the products was achieved using Fourier‐transform infrared spectroscopy (FTIR), ¹H‐nuclear magnetic resonance (¹H‐NMR), ¹³C‐nuclear magnetic resonance (¹³C‐NMR), Gas chromatography–mass spectrometry (GC–MS), gel‐permeation chromatography (GPC), thermogravimetric analysis (TGA), and fractional precipitation (γ) techniques. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010