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In this work, monodisperse positively charged polystyrene (PS) particles with a particle size of 900 nm were prepared by dispersion polymerization using methacryloxyethyltrimethyl ammonium chloride (DMC) as a cationic comonomer. The polystyrene/silica (PS/SiO2) composite microspheres with a raspberry structure are formed by electrostatic adsorption prepared using positively charged PS adsorbed negatively charged silicon dioxide (SiO2). A novel superhydrophobic coating was constructed by a dip-coating method. Then, the coating film was immersed in a solution of heptadecafluorodecyl trimethoxysilane in n-hexane (0.1 wt%) to carry out surface superhydrophobic modification. Finally, a superhydrophobic coating with 158° static contact angle and 3° sliding angle was obtained. In addition, by adding divinylbenzene (DVB) and changing the amount and size of SiO2, the effect of the roughness level and cross-linking structure of raspberry particles on the hydrophobic properties of the coating was studied. Mechanism diagram of superhydrophobic coating prepared by PS/SiO2 composite particles.

Monodisperse polystyrene microspheres with different functional groups have important applications in both the medical and analytical fields. In this study, we prepared monodisperse microspheres with sulfonic acid or carboxyl groups using soap-free emulsion polymerization (SFEP) with potassium persulfate as the initiator. A series of monodisperse polystyrene microspheres with sizes between 100 and 500 nm were successfully prepared by copolymerizing different types of ionic monomers at different concentrations. The microspheres were characterized by using dynamic light scattering (DLS), Zeta potential measurements (ZP), FT-IR spectroscopy, and transmission electron microscopy (TEM). The mechanism of the particle nucleation and growth were studied by combining the changes in particle size and the number of particles. The results showed that the addition of hydrophilic comonomers like sodium p-styrene sulfonate, acrylic acid, and methacrylic acid significantly improved the stability of the polystyrene microspheres and promoted particle nucleation, resulting in less particle aggregation and microspheres with smaller sizes.

A novel nanocomposite proton-exchange membrane (PEM) was obtained by combined electrospinning and solution casting of a composite solution of sulfophenylated poly(ether ether ketone ketone) (SP-PEEKK) and maleic anhydride modified nanocellulose (MN). SP-PEEKK was prepared by polymerization between phenyl hydroquinone and 1,4-bis(4-fluorobenzoyl)benzene followed by post-sulfonation. Nanocellulose (NCC) was prepared by the acid treatment of MCC with sulfuric acid, and MN with carboxyl group was obtained by modifying NCC with maleic anhydride. PEMs with 2% MN (MN2) showed a water uptake of 28% at 100°C, which was higher than that of MN0 (with 0% MN content). MN2 possessed a high tensile strength of 48.7 MPa, Young’s modulus of 1.3 GPa, and elongation at break of 34%, which was 54%, 21%, and 16% higher than those of MN0, respectively. Thus, the ordered distributed of MN was illustrated to be the effective reinforcing material for SP-PEEKK membranes because of the strong interface between the hydroxyl group of rigid MN and the sulfonic acid group of SP-PEEKK. MN2 also had a substantially higher proton conductivity of 0.09 S cm−1 at 90°C than MN0 (0.037 S cm−1). Therefore, combined electrospinning and solution casting was found to be a promising choice to improve the proton conductivity of nanocomposite PEMs, as promoted by the three-dimensional hydrogen bond-proton-transport network formed by the well-oriented MN in SPEEKK produced by the electrospinning.

Phosphoric acid-doped polybenzimidazole (PA-PBI) used in high-temperature proton exchange membranes (HT-PEMs) frequently suffers from a serious loss of mechanical strength because of the “plasticiz...

Several high-molecular-weight pillar[5]arene-containing poly(arylene ether sulfone) polymers were synthesized for the first time. Through grafting and crosslinking approaches, networks consisting of the molecular chains bearing multiple long-chain quaternary amine salts were fabricated. For the crosslinked membranes, high conductivity and low swelling were achieved even at low ion exchange capacity.

As is well known, changing continuous phase properties has a great influence on the nucleation mechanism and particle size, and the addition of electrolytes or alcohol is the main mean to c...

Study on proton exchange membrane (PEM) with the aim toward excellent battery performance of PEM for fuel cells has attracted increasing attention. In this work, nanocellulose (CNC) aminated by KH792 noted as NN was prepared. CNC or NN/sulfophenylated poly(ether ether ketone ketone) (sPEEKK) nanocomposite membrane (SN) or (SNN) were produced by solution mixing. SNN was further coated with tetraethyl orthosilicate (TEOS) to obtain SNNT. The properties of sPEEKK, SN, SNN, and SNNT membranes were thoroughly investigated. The proton conductivity of SN4 was 0.22 S·cm⁻¹ at 90 °C, while a proton conductivity of 0.30 S·cm⁻¹ was obtained for SNN4, and an even higher value of 0.36 S·cm⁻¹ at 90 °C was obtained for the TEOS‐coated SNN4 (SNN4T). Meanwhile, SNN4T showed high thermal stability, and its Td₅ was as high as 318.2 °C. Furthermore, the composite membrane coated with TEOS also presented excellent oxidative stability. The mass of SNN2T after treated in Fenton agent for 1 h at 80 °C was still retained 96.2%, and it was not fully dissolved until 11 h. It was illustrated that aminated CNC/sPEEKK nanocomposite membranes coated with TEOS is a kind of promising materials as PEMs for fuel cells. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2190–2200

In this study, a novel approach for preparing 50 wt% solid content cationic poly(methyl methacrylate) (PMMA) latexes with narrow particle size distribution (PSD) using macroemulsion polymerization ...

Lignin is the second most abundant source of renewable raw materials. In this study, a novel oxidation method for lignin by ozone was reported to obtain oxidized lignin (OL). The hydroxyl content of lignin was increased, and the content of phenolic hydroxyl was increased from 0.715 to 1.015 mmol/g when the ozone oxidized time was 0.5 h. Then the OL was used to substitute part of PEG200 and react with isocyanate to produce lignin-based PU pre-polymer. After curing, oxidized lignin based PU (OLPU) was obtained. Owing to the rigid aromatic structure of lignin and crosslinking, the OLPU presented excellent properties. The 0.5-OL20PU (lignin was oxidized 0.5 h by ozone with the rate of 3.2 g/h, and the lignin content was 20% in OLPU) presented the tensile strength of up to 47.2 MPa, and its gel content reached 97.9%. The OLPU film also presented high hydrophobicity and thermal stability. The hardness of OLPU coatings could be 2H. Thus, the lignin oxidized by ozone can be applied in the lignin based PU, and the oxidized lignin based PU is promising for the wider application.

Organosolv lignin (OL) was used to synthesize organosolv-lignin-based epoxy acrylate (OLBEA) coatings. The reaction process was determined by epoxy and acid values. OLBEA coatings were prepared by dual (Ultraviolet (UV) and thermal) curing to achieve a deep and complete process. The structures of lignin-based epoxy (OLBE) and OLBEA were characterized by Fourier transform infrared spectroscopy (FTIR). The properties of the dual- and UV-cured coatings were then compared by measuring gel content and mechanical properties. Results revealed that the dual-cured films had higher cross-linking degree and better mechanical properties than the UV-cured films. The chemical resistance of the dual-cured coatings was also examined. The properties of OLBEA coatings obtained by dual curing were shown to be excellent and promising for wide-ranging applications.

Some multi-ether linked polyimides (PIs) derived from two diamine monomers containing various amount of cyano groups are synthesized by a typical two-step polymerization. Meanwhile, the PIs with similar chemical structure but without cyano groups are prepared as counterparts for comparison purposes. The obtained PIs exhibit low glass transition temperature values of 211–258°C, which are associated with their multi-ether chemical structure. Furthermore, these PIs have high thermal stability, and the temperatures at 10% weight loss are in the range of 524–616°C under nitrogen atmosphere. It is found that the introduction of cyano groups would have a great influence on the properties of the PIs. The tensile strength and Young’s modulus of one cyano-containing PI reach 121 MPa and 1.4 GPa, respectively, which are much higher than those cyano-free ones. In addition, the cyano-containing PIs exhibit different behaviors of dielectricity and solubility in comparison with the corresponding cyano-free counterparts.

In this work, lignin based epoxy acrylate (LBEA) oligomer with various percentage of lignin was in situ synthesized with epoxy and acrylic acid. The first step was the etherification between lignin and epoxy to produce lignin based epoxy (LBE), and the second step was the esterification between LBE and acrylic acid to synthesize LBEA. Epoxy value and acid value were measured to determine the reaction conditions of the two steps, respectively. The structure of prepared LBEA was confirmed by Flourier infrared spectroscopy (FTIR) characterization. LBEA coatings were prepared through ultraviolet radiation curing method. The gel content, chemical resistance, mechanical properties and thermal properties of coatings were investigated. It was found that the mechanical properties and chemical resistance were much improved than those of epoxy acrylate (EA) resin with the addition of lignin. Thus, lignin was proved to be a new promising biomaterial which could be applied in biobased EA coatings.

In this work, the polyethylene (PE) separator is firstly modified with bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) solution, and then coated with a solution of hydroxyl functionalized carbon nanotube (CNT), nano-SiO 2 and polyvinyl alcohol (PVA) on its one side. The obtained composite separator (PE@LiSiO2 CNT) is with a thermal shrinkage of 14% at 150 °C for 0.5 h, and the ionic conductivity can be as high as 1.69 × 10 -3 S cm-1 . Furthermore, the specific discharge capacity of the assembled lithium ion batteries (LIBs) reaches 164 mAh g -1 at 0.2 C, and the coulomb efficiency remains above 99% after 250 cycles. This can be attributed to the network structure of SiO2 and CNT which increases the porosity of the separator and improves the electrolyte uptake. Besides, the CNT effectively alleviates the self-aggregation of SiO2 , and promotes the rapid electrochemical reactions between the separator and the cathode. And it can also allow the free diffusion of lithium ions through its walls and channels with high efficiency, thus reducing the charge transfer resistance and improving the battery performance. Therefore, the modified separator with excellent dimensional thermal stability and electrochemical performance are successfully obtained, which are helpful to the development of LIBs.

A series of cyano-functionalized polyimides (CN-PIs) were prepared and derived from a novel diamine monomer having cyano and biphenyl groups. Meanwhile, another series of PIs without cyano groups (H-PIs) were prepared as counterparts for comparison purposes. Both series of PIs exhibited good solvent resistance, good thermal stability, remarkable film-forming ability, and excellent tensile properties. The Tg values of CN-PIs were 260–330°C, which were 10–17°C higher than the corresponding –CN free H-PIs. The CN-PIs exhibited no obvious decomposition below 470°C, and their 5% weight loss temperatures were above 568°C under nitrogen atmosphere. All the CN-PI films had high tensile strength and Young’s moduli, which were related to their rigid backbones and strong interactions between molecular chains. Due to their higher molar polarization, CN-PIs expressed the higher dielectric constants (3.29–3.69 at 1 MHz) in comparison with the corresponding H-PIs. CN-PIs exhibited the improved transparency, and both CN-PIs and H-PIs had better transparency than commercial Kapton® film. Introducing –CN groups could have an effect on the coefficient of thermal expansion and peel strength of the PIs. The peel strength of the PI, which was derived from cyano-functionalized diamine monomer and 4,4′-oxydiphthalic anhydride, could even reach 1.10 N mm-1, suggesting its strong interaction to copper matrix and potential use in flexible circuit board.

A series of poly(arylene ether ketone)s (PAEKs) with dense sulfonic-acid-functionalized pendants were successfully synthesized by the Ullmann C–N coupling of a polymer precursor containing pendant iodobenzene rings and 3,6-ditrityl-9H-carbazole, followed by sulfonation using chlorosulfonic acid. A tough transparent membrane, which exhibited suitable dimensional stability and high proton conductivity, was obtained by casting an N,N-dimethylacetamide polymer solution. DSPAEK-CZ-25 (IEC = 2.03 meq. g−1, where IEC = ion-exchange capacity) exhibited the highest proton conductivity of 177 mS cm−1 at 100 °C; this value is significantly greater than that of Nafion 117. In terms of molecular design, the large difference in polarity between the fluorinated polymer backbone and the concentrated pendant sulfonic acid groups possibly induces good phase-separation morphology, which enhances conductivity and dimensional stability. The obtained membranes exhibited excellent thermal stabilities and good mechanical properties. Overall, the DSPAEK-CZ polymers exhibited outstanding comprehensive performance as potential materials for proton exchange membranes (PEMs).

The structural evolution of polyacrylonitrile (PAN) homopolymer during thermal oxidative stabilization (TOS) was tracked quantitatively by using fourier transform infrared spectroscopy (FTIR) and curve-fitting technology. The cyclization, dehydrogenation of linear PAN macromolecule chains, oxygen uptake reactions of linear PAN macromolecule chains and cyclic structures were discussed in detail through tracking quantitatively the evolution of some specific groups. The cyclization, dehydrogenation and oxygen uptake reactions were evolved synchronously at the initial stage of TOS processes, but dehydrogenation and oxygen uptake reactions became dominant as cyclization extent above 0.7. Based on the data from FTIR and curve-fitting, a new procedure was developed to calculate the formed cyclic structures. The cyclic structures formed at 250 °C possessed length about seven successive aromatic rings; however, the cyclic structures formed at 265 °C possessed length about six successive aromatic rings. The graphite-like structures of the carbonized PAN films which were stabilized at 250 °C possessed were better than that of the carbonized PAN films which were stabilized at 265 °C.

Highly uniform polymer latex particles with controlled particle size have been widely applied in many fields such as nanotechnology, drug delivery, biomedical separation, and material templates. Since the particle size plays a critical role in determining the application fields, various technologies such as two-stage swelling method and dynamic swelling method have been used to control the particle size in the polymerization process. However, these methods usually need a multi-step polymerization reaction and long reaction time. This review focuses on a method of controlling particle size, that is, particle coagulation technology. Particle coagulation technology can be used to produce large sized, monodispersed polymer particles by soap-free emulsion polymerization, macroemulsion polymerization, and dispersion polymerization. In this review article, an overview of the concept of particle coagulation is given, followed by the description of the particle coagulation process in different polymerization systems. Some representative publications about particle coagulation were also reviewed, especially the effect of reaction parameters on the particle coagulation extent and time. Finally, the relationship between the particle coagulation and particle size distribution is reviewed extensively.

A synthetic approach to poly(arylene ether ketones) grafted with super-acidic perfluoroalkyl-sulfonic-acids is reported. A series of iodo-containing poly(arylene ether ketone)s derived from a 4-iodophenylated hydroquinone monomer were synthesized by aromatic nucleophilic substitution (SNAr). The iodo-containing polymers were functionalized via the Ullmann reaction to give poly(arylene ether ketone)s grafted with perfluoroalkyl-sulfonic-acid. The perfluoroalkyl-sulfonic-acid functionalized aromatic polymers were investigated as proton exchange membranes (PEM). The membranes had good overall properties of thermal-oxidative stability, mechanical strength, methanol permeability and proton conductivity. A membrane with IEC ~ 1.37 meq g − 1 had a proton conductivity of 0.088 S cm − 1 at 100 °C, which was higher than many sulfonated hydrocarbon PEMs with similar IEC values.

In this work, a kind of novel flexible lignin-based electromagnetic shielding polyurethane (FeCLPU) with excellent properties was prepared and studied. Lignin was applied as an reinforcement with modified carbon nanotubes (CNT) and aminated ferroferric oxide nanoparticles (Fe3O4) in polyurethane to improve electromagnetic shielding properties. The KH550-modified Fe3O4 was mixed with lignin, polyethylene glycol (PEG), hexamethylene diisocyanate (HDI) and modifiedCNT to in situ synthesize FeCLPU. When the concentrations of both Fe3O4 and CNT were 10% and the lignin content was 15%, the maximum EMI SE reached 37.5 dB. This excellent electromagnetic shielding effectiveness was attributed to the synergistic effects between the Fe3O4 , CNT and lignin. The tensile strength attained 7.25 MPa. Thus, the FeCLPU with uniformly dopped Fe 3O4 and CNT was expected to be promising in a wide array of applications in civilian fields, due to its excellent overall performance, low cost and eco-friendliness.

In this work, hierarchical flower-like Ni-doped Co3O4 was synthesized via a facile one-step coprecipitation method. In the synthesis process, a series of solvent-dependent experiments were carried out to investigate the effect of ethanol/water ratio (R-E/W) on samples. With the increasing ethanol/water ratio, the doping concentration of Ni2+ increased and the microstructure evolved from micro-leaves to micro-flowers. Additionally, gas sensors based on prepared materials were fabricated to evaluate their gas sensing properties. The comparative analysis illustrated that the sensor based on 5.3 mol% Ni-doped Co3O4 microflowers (R-E/W = 3/30) presented the highest response (8.34) to 100 ppm n-butanol at low optimum temperature (165 °C), with a response/recovery time of 59/63 s, and it also exhibited excellent anti-humidity properties and long-term stability. The unique hierarchical flower-like microstructure and the optimized parameters (catalytic sites, carrier concentration, ratio of Co2+, oxygen component) caused by the doping of Ni were responsible for the improved gas sensing performance. Therefore, this work presented a simple solvent-dependent route to controllably synthesize Ni-doped Co3O4 sensing material, and the excellent gas sensing properties of the sensor based on 5.3 mol% Ni-doped Co3O4 microflowers revealed a great application prospect in detecting n-butanol.

A novel approach to prepare sub-200 nm, narrowly dispersed polystyrene latex particles is proposed for the emulsion polymerization of a ca. 40 wt% solid-content solution. The presented method exploits the cationic comonomer methacryloxyethyltrimethyl ammonium chloride (MATMAC) or the initiator 2,2′-Azobis (2-methylpropionamidine) dihydrochloride (AIBA) to generate cationic oligomeric radicals shielded the negatively charged surfactant molecules adsorbed on the particles surface, further induced particle coagulation by in situ charge neutralization. By adjusting the types and amounts of the comonomer, the extent of the in situ charge neutralization is controlled. In consequence, the extent of the particle coagulation is controlled, resulting in the production of large-size latex particles. The particle coagulation induced by in situ charge neutralization occurs at the particle nucleation stage, which extends the times of particle completive growth and reversible coagulation, and therefore, narrowed the width of the particle size distribution of the ultimate latex particles. The resulting colloidal latexes containing 40 wt% solid content are very stable by presenting the absolute value of zeta potentials larger than 40 mV. This approach is likely to be used for large-scale industrial productions of narrowly dispersed polymer particles.

In order to investigate the effect of cyano groups (–CN) on the properties of the polymers, two series of polyimides (PIs) based on a –CN-containing diamine monomer and a diamine monomer without –CN group were synthesized and characterized, respectively. After studying the structure–property relationships of these polymers, it was found that some properties could be greatly improved with the incorporation of –CN groups. Firstly, the tensile test showed that the –CN-containing polymeric films had higher tensile strength and Young’s moduli. The tensile strength and the Young’s modulus of 4,4′-(hexafluoroisopropylidene) diphthalic with –CN groups anhydride reached 154.1 MPa and 1.66 GPa, respectively. Secondly, thermogravimetric analysis results revealed that the –CN-containing polymers (CN-PI polymers) had good thermal stability and exhibited no decomposition below 470°C under nitrogen atmosphere. Thirdly, the dielectric constants of the CN-PI polymers were in the range of 3.67–3.84 at 10 MHz, which had an increase of 0.5 in comparison with the corresponding PIs without –CN groups. Fourthly, the CN-PI polymers had higher peel strength to copper foils. The peel strength of 4,4′-biphenyltetracarboxylic dianhydride-containing –CN groups could reach 1.28 N mm−1, suggesting its strong interaction to copper matrix and the potential use in flexibility circuit board. Finally, all the films showed better optical transparency compared with DuPont’s Kapton® film.

Acrylonitrile-butadiene-styrene (ABS) grafted copolymer prepared by emulsion polymerization was used to modify different molecular weight poly (vinyl chloride) (PVC) resins. The effects of the molecular weight of the PVC resins on dynamic mechanical analyses (DMA) of PVC/ABS blends and matrix plasticizing behavior on the impact mechanical properties and the morphology were investigated. The tan δ peaks of PVC/ABS blends occurred at the same temperature obtained by DMA, indicating that miscibility of PVC/ABS blends was independent of the molecular weight of PVC. The notched Izod impact test results indicated that the amount of polybutadiene (PB) rubber needed for the brittle-ductile transition (BDT) increases together with the molecular weight of PVC when milled at 165°C. Increasing the operation temperature and adding the plasticizer dioctyl phthalate (DOP) could change the matrix plasticizing extent and the BDT. At a milling temperature of 165°C, the BDT was reached only with 3.6 wt% PB when DOP was added, in contrast to the addition of 7.2 wt% PB in the absence of DOP. The morphology of different plasticized degree of PVC/ABS blends was studied by transmission electron microscopy (TEM) showing that the PVC-1/ABS blends milled at 165°C showed a larger unstained area than the other series of PVC blends.

The particle coagulation technology in emulsion polymerization is a novel and facile approach to prepare large-scale, narrowly dispersed latex particles. However, the formation of narrowly dispersed latex particles under particle coagulation at a high zeta potential is surprising. To elucidate this observation, a detailed investigation on the relationship between particle coagulation and particle size distribution was carried out. Unlike the conventional emulsion polymerization, a rapid decrease in the particle number and an increase in the particle size were clearly observed during the polymerization. The results confirm the occurrence of particle coagulation. The width of zeta potential and particle size distribution also decreased with particle coagulation, resulting in large-size, narrowly dispersed latex particles. These phenomena were explained by the competitive growth mechanism.

A novel lignin-based flame retardant (LMD) is synthesized in this work via the in-situ reactions of lignin, diphenylmethane diisocyanate (MDI), and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). Flame-retardant polyurethane (FLPU) is prepared by the co-curing of LMD and prepolymer synthesized by lignin, MDI, and polyether polyol 204. Polyethylene glycol (PEG) 2000 is also added to adjust the flexibility of the lignin-based polyurethane (LPU). The limiting oxygen index (LOI) value of the FLPU gradually increases with the LMD content and can reach 29.9% for F30-L20-L15-80PU (L20MD content is 30% in L15-80PU), exhibiting excellent flame-retardant properties. The hardness of the FLPU for the optimized formulation is 2H, the adhesion is 0, and the flexibility is 2 mm. And the impact resistance is greater than 100 cm/1000 g. These outstanding properties illustrate the LMD is excellent flame retardants and reinforcing materials for LPU. The interface can be strengthened by the co-curing between the LMD and the LPU prepolymer.

This work is an extension of previous research results reported by our team (Colloid Polym Sci 292:519–525; 1347–1353), where how to control particle size distribution by adjusting particle coagulation has been investigated. There is limitation in previous studies, that is, the particles taking part in coagulation only possess a linear structure. However, the crosslinking network structure is necessary to many fields, such as rubber and plastic modifier. Thus, it is very significant to investigate the effect of the crosslinking network structure on particle coagulation for understanding the nature of particle coagulation and controlling particle size distribution. In this manuscript, dihydrodicyclopentadienyl acrylate (DCPA) is chosen as a crosslinker to copolymerize with styrene to promote particle structure shift from the linear to the crosslinking network structure and to investigate further the coagulation behavior of the particles with the crosslinking network structure. Experimental results are explained by the collision frequency of particles and stability dependence of the particle structure.

This work is an extension of previous research results reported by our team (Colloid and Polymer Science 2013, 291: 2385-2398), where large scale and high solid content latexes of poly(n-butyl acrylate) were obtained with the particle coagulation method induced by the electrolyte. However, how to prepare controlled particle size distribution polymer latex has not been studied. Thus, in this study, the effect of the monomer/water ratios and electrolyte concentrations on particle formation and growth methods were studied by following the tracks of the evolutions of particle size, number and distribution as a function of reaction time or conversion. Experimental results showed that the length of time that particle nucleation occurred increased with increasing monomer charged for the systems without electrolyte. A point worthy of attention here is that homogeneous nucleation may occur at high monomer concentrations (30/70, 40/60). However, electrolyte added could be made the nucleation mechanism shift from mi...

A series of asymmetric membranes based on a trifluoromethylphenylated poly(ether ether ketone) (CF3-PEEK) were prepared using a dry–wet phase inversion method. To obtain the asymmetric membranes with defect-free skin, the type and concentration of internal nonsolvent and the evaporation time were carefully investigated. The cross-section of membranes was characterized by scanning electron microscopy. The gas separation performance of asymmetric membranes was tested in terms of gas permeabilities and selectivities for helium, carbon dioxide (CO2), oxygen (O2), and nitrogen by the constant volume method. It was found that the permeabilities of asymmetric membranes were obviously higher than that of CF3-PEEK dense membrane. The membranes in series 2 showed higher permeability for each gas while the separability for gas pair CO2/O2 increased from 3.78 to about 6 comparing with that of the dense membrane.

The poly(methyl methacrylate-co-styrene) was prepared by batch emulsion polymerization to clarify the effect of characteristics of polymer on particle coagulation. Experimental results showed that the size of final latex particle increased with increasing methyl methacrylate in initial recipe, ranged from 84 to 193 nm, which was attributed to the particle coagulation. With the methyl methacrylate increased, the hydrophilicity of polymeric particle improved, thus led to the surfactant molecules packed loosely on the polymer surface, further, enhanced particle coagulation occurred. On the contrary, the surfactant molecules adsorbed on tightly the polymeric particle surface (methyl methacrylate content low) surface led to the electrostatic repulsion energy of polymer particle improved, and polymer particle stability was also improved. Thus, combined with the results previously reported by us (Colloid Polym Sci 291: 2385–2398, 2013 and Colloid Polym Sci 292: 519-525, 2014), the particle coagulation depended not only on the aqueous phase such as electrolyte concentration and methanol content, but also on the nature of polymer such as hydrophilicity.

Both multitrifluoromethylated polyimide (12F-PI) and sulfophenylated polyetheretherketone (Ph-SPEEK) were synthesized in order to build immiscible blends for proton exchange membranes (PEMs). The 12F-PI/Ph-SPEEK blend membranes had improved dimensional stability and oxidation stability in comparison with pure Ph-SPEEK. Despite the introduction of the hydrophobic 12F-PI content, the proton conductivity of blends 1 and 2 showed significantly increased proton conductivity at 80–100°C. The interesting phase-separation morphology, in which the “inorganic-like” particles formed by 12F-PI dispersed in Ph-SPEEK, was observed. This morphology similar to inorganic–organic blends could be highly related to the big differences in the hydrophobicity/hydrophilicity and backbones of two polymers. The obtained results suggest that this series of blend membranes may be potential PEMs for fuel cells.

This work is an extension of previous research results reported by our team (Colloid Polym Sci 291:2385–2389, 2013), where monodisperse, large-scale, and high-solid-content latexes of poly(n-butyl acrylate) were obtained with the particle coagulation method induced by the electrolyte. However, large-scale polystyrene latex particle is difficult to synthesize with this approach; moreover, demulsification phenomena easily take place especially in high solid content. In this article, a new approach to prepare large-scale polystyrene latex particle was proposed. Methanol was added to aqueous phases to decrease the interfacial tension between the polymer particle surface and continual phases, further decreasing interfacial free energy. Consequently, the surfactant molecules would loosely pack on the polymer particle surface, which is favored by particle coagulation. Experimental investigations showed that the final polystyrene particle scale only reaches to 93.5 nm when the methanol/water ratio is equal to 0:100, but the particle size attains 270 nm when the methanol/water ratio is equal to 30:70. These results indicated that polystyrene particle coagulation can be induced by methanol by varying the surfactant molecule adsorption on the particle surface. This investigation also provided a new simple approach to prepare large-scale, stable latex particles.

A series of novel high molecular weight fluorinated co-polyimides (Co-PIs) containing styryl side chain based on 1,3-bis(2-trifluoromethyl-4-aminophenoxy)-5-(2,3,4,5-tetrafluorophenoxy)benzene (6FTFPB) were successfully synthesized. The weight-average molecular weights (Mws) and polydispersities of the co-polyimides were in the range 8.93–10.81 × 104 and 1.33–1.82, respectively. The co-polyimide film showed excellent solubility in organic solvents, high tensile properties (tensile strength exceeded 91 MPa), excellent optical transparency (cutoff wavelength at 332–339 nm and light transparencies above 89% at a wavelength of 550 nm), and high thermal stability (5% thermal weight-loss temperature up to 510 °C). The casting and spinning films could be cross-linked by thermal curing. The cured films show better combination property (including excellent resistance to solvents) than that of co-polyimides. For instance, the glass transition temperature of Co-PI-1 (the molar weight ratio of 6FTFPB was 30%) increased from 217 to 271 °C, the tensile strength enhanced from 94 to 96 MPa, the 5% thermal weight-loss temperature improved from 514 to 525 °C. Moreover, after cured, Co-PI-1 film also has a coefficient of thermal expansion (CTE) value of 60.3 ppm °C−1, low root mean square surface roughness (Rq) at 4.130 nm and low dielectric constant of 2.60. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 349–359

A series of triple-layer membranes were prepared based on a sulfonated polyimide (SPI) and a traditional sulfonated poly(ether ether ketone) (SPEEK) polymer matrix. Compared with the single-component membranes (pure SPI and SPEEK), the multicomponent membranes exhibited better comprehensive performance. Interestingly, the triple-layer membranes possessed improved mechanical properties, lower water uptake, and swelling ratio than those of the corresponding blend membranes. When the contents of SPI were 30 and 40%, the triple-layer membranes even had lower methanol permeability (3.42 and 2.61 × 10−7 cm2 s−1, respectively) than that of the pure SPI membrane (3.51 × 10−7 cm2 s−1). The proton conductivity of the triple-layer membranes was in the range of 0.117–0.149 S cm−1 at 100°C. All the results suggest that the triple-layer membranes have sufficiently excellent performance to be applied in fuel cells.

Seeded emulsion polymerization and agglomerating method were well-known techniques for the production of polymeric latexes with large particle size and high solid content. Obtaining latexes with monodisperse and particle size above 300 nm scale, however, was time-consuming and difficult by means of these methods. Here, stable, monodisperse latexes with the controlled particle diameter (55–650 nm) and high solid content (60 wt%) were synthesized via one-step in batch emulsion polymerization. Experimental investigations show that the particle size increased with decreasing emulsifier concentrations and increasing monomer/water ratios or electrolyte concentrations. The latex particle coagulation was considered as the dominant particle formation and growth method, which could be proved by the evolutions of particle number as well as dimension against conversion. Latex particle coagulation occurred if the particle surface covered ratio dropped between the critical surface covered ratio (θ crit = 0.59) and the lowermost surface covered ratio (θ low = 0.38). In addition,θ crit and θ low were increased with electrolyte concentrations.

A novel soluble polybenzimidazole with a pendant phenyl group (Ph-PBI) was successfully synthesized based on 4,4′-(1,4-phenylenedioxy-2-phenyl) dibenzoic acid and diaminobenzidine. A phenylated sulfonated poly(ether ether ketone) (Ph-SPEEK) with a similar chemical structure to Ph-PBI was selected as matrix. Ph-SPEEK/Ph-PBI membranes were produced by a solution method. The obtained blend membranes exhibited much higher thermal stability as well as oxidative stability and lower water uptake than the pristine Ph-SPEEK membrane. The proton conductivity of the blend membranes could be in the range of 0.0374–0.1456 S cm−1 at 100°C. As a result, the blend membranes also showed improved mechanical properties that may be related with the acid–base interactions between the two components.

A new family of sulfonated fluorenyl-containing poly(ether ether ketone ketone)s (SFPEEKKs) were successfully synthesized through a mild postsulfonation in concentrated sulfuric acid at room temperature. Further, a series of “molecule-enhanced” blend membranes were prepared based on SFPEEKKs and an amino-functionalized poly(ether ether ketone) by the solution casting method. These blend membranes generally showed higher thermal stability, lower swelling ratio and methanol permeability and superior mechanical properties in comparison with pristine SFPEEKK membranes. The results showed that some blend membranes may be promising proton exchange membranes for fuel cell applications. Open image in new window

A hydroxylated poly(aryl ether sulfone) (PES-OH) was synthesized by a demethylation reaction of a methoxy-functionalized PES (PES-OCH3) using the HCl/pyridine system. Derived from this hydroxylated PES precursor, bulky (2-trifluoromethyl-4-nitro) phenyl (TFN) and benzophenone (BZP) were introduced to the PES backbones as side groups via aromatic nucleophilic substitution reactions. A direct property comparison of PES-OH, PES-OCH3, PES-TFN and PES-BZP has been made, and these analogues exhibited different solubility, thermal properties and gas permeability. PES grafted with the trifluoromethyl side group (PES-TFN) demonstrated more attractive permeabilities and permselectivities for O2/N2 separation compared to the others, and it exhibited the best P(O2)/P(N2) value of 8.44.

This article was to provide some new insights into the influences of itaconic acid (IA) content in polyacrylonitrile (PAN) copolymers on polymerization, structural evolution, thermal behaviors and carbon yield relatively comprehensively. High IA containing poly(acrylonitrile-co-itaconic acid) (PAI) oligomers were successfully extracted from PAI copolymers with 2.0 and 3.0 mol % IA. PAI copolymers with 0.5 mol % and 1.0 mol % IA possessed more cyclized structures, conjugated carbonyl group, conjugated nitrile group, and less β-amino nitrile group as well as faster structural evolution rate than those of the other three PAI copolymers. Kinetic parameters indicated that excessive IA content in PAI copolymer did not have advantages in promoting cyclization reaction. The PAI copolymers with 0.5 wt % to 1.0 mol % IA possessed better crystalline parameters as well as higher carbon yield than those of the other two PAI copolymers after carbonization at 1350 oC. In summary, PAI copolymers with 0.5 mol % to 1.0 mol % IA will be more suitable for fabricating of high performance PAN-based carbon fibers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43919.