Characterization and dual functionalization of polystyrene with propionic anhydride and cyanate derivatives

First, Friedel–Crafts reactions were used for the acylation process. For this, polystyrene (PS) was reacted with propionic anhydride in the presence of Lewis acid catalyst. The amount of acyl group linked PS as a result of acylation has been identified as volumetric. Second, the bromination and lithiation reactions of acylated PS containing carbonyl groups were realized. Also, the lithiated PS containing acyl groups has been modified a second time with various isocyanates and isothiocyanate derivatives in the presence of n?BuLi catalyst. Some important reaction parameters were assigned in order to optimize the process. The structure all of the products were characterized by Fourier transform infrared, ¹H NMR (Proton Nuclear Magnetic Resonance), and thermogravimetric methods. In addition, reaction yields were determined according to the result of elemental analysis. Dual functionalization yields were realized between 62.2% and 69.9%. For kinetic analysis, the TG/DTG (Thermal Gravimetric Analysis/Differantial Thermal Analysis) data obtained at three different heating rates were processed by Kissinger–Akahira–Sunose method. The results demonstrated that the acylation reaction, bromination and lithiation reactions, and dual functionalization reactions with cyanate derivatives can be carried out to obtain a significantly functionalized polymer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1351‐1362, 2013     

Enhancement of mechanical properties and interfacial adhesion of PP/EPDM/flax fiber composites using maleic anhydride as a compatibilizer

In order to improve the compatibility between natural fibers and polypropylene (PP) and polypropylene‐ethylene propylene diene terpolymer (PP‐EPDM) blends, the functionalization of both matrices with maleic anhydride (MA) is investigated in this study. The morphological observations carried out by scanning electron microscopy show that the incorporation of small amounts of functionalized polymer considerably improves the adhesion at the fiber‐matrix interface. In these cases, the fibers are perfectly embedded in the matrix in relation to the composites prepared with the pure homopolymers, and a significant increase in the composite strength is also observed, particularly, after the incorporation of both modified polymers (MAPP and MAEPDM). Thus, it is possible to correlate better interfacial adhesion with the improvement of mechanical properties. It is assumed that the functionalization of the matrix reduces interfacial stress concentrations and may prevent fiber‐fiber interactions, which are responsible for premature composite failure. The crystallization kinetics of PP were also analyzed by differential scanning calorimetry (DSC). It was observed that both flax fiber and rubber behave as effective nucleant agents, accelerating PP crystallization. Moreover, these results are particularly relevant when the grafted matrices are added to the composite. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2170–2178, 2003     

Demulsification efficiency of some novel styrene/maleic anhydride ester copolymers

Four demulsifiers were prepared in three steps. In the first step, styrene and maleic anhydride were copolymerized. In the second step, a long‐chain alcohol (dodecanol) was reacted with the prepared copolymer to form the monoesterified copolymer. In the final step, the resulting product was further esterified with poly(propylene oxide) (PPO)–poly(ethylene oxide) (PEO) block copolymers of different molecular weights (1.1, 2.5, 3.0, 5.0, and 8.0 × 10³) and different PPO/PEO ratios. The demulsification efficiency of these demulsifiers was investigated with the bottle test (Sany glass). The effects of the molecular weight and ratio of the PPO–PEO block copolymers on the demulsification efficiency were studied. The demulsification efficiency could be enhanced from 66% by an individual demulsifier to 100% by demulsifier blends. The surface‐active and thermodynamic properties of the prepared demulsifiers were measured at 25, 35, and 45°C. The kinematics of the demulsification process were photographed with a binocular microscope. The demulsification mechanism was found to occur in three stages, that is, adsorption and flocculation, coalescence, and channel formation followed by separation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Sulfonated and cross-linked polystyrene ultrafine fibers for the esterification of palmitic acid for biodiesel production

For the need of green and sustainable development, a fibrous solid acid catalyst was developed for the transformation of low cost oils to biodiesel in an efficient and green manner. Polystyrene was electrospun into ultrafine fibers with mean diameter of ~1.34 μm, and then simultaneously cross-linked and sulfonated in sulfuric acid/acetic acid mixed solvent with paraformaldehyde as the external cross-linker. The cross-linking and sulfonation degrees were controllable by changing the ratio of sulfuric acid/acetic acid. After sulfonation and cross-linking, the solvent resistance, chemical structure, and composition of these fibers were separately characterized by scanning electron microscopy, infrared spectroscopy, and elemental analysis. At last, this novel fibrous solid acid catalyst was used to catalyze the esterification reaction of palmitic acid and methanol for biodiesel production. After optimizing the reaction conditions, this fibrous solid acid catalyst can catalyze the esterification of palmitic acid and methanol with the conversion up to 92% under mild reaction conditions. Moreover, due to the fibrous structure, this fibrous solid acid catalyst could be readily separated and reused.     

Adhesion of maleic anhydride functionalized polyolefins and blends

We study three new classes of olefin‐based polymer, low‐molecular‐weight homopolypropylene (LMW‐hPP), syndiotactic‐rich polypropylene (srPP), and random propylene polymer (RPP). RPP is a random propylene/ethylene copolymer. By blending LMW‐hPP with 20 wt % of a maleic anhydride (MA) functionalized srPP (MA‐srPP) or MA functionalized RPP (MA‐RPP) instead of a commercial MA‐iPP (maleic anhydride‐grafted‐isotactic polypropylene), adhesion to a polar substrate, such as polyester (Mylar), is greatly enhanced. Effects of crystallinity controlled by either stereoregularity or comonomer incorporation and molecular weight of these MA functionalized propylene‐based polymers on adhesive performance are discussed. To further understand the mechanisms of enhanced adhesion, Sum Frequency Generation (SFG) spectroscopy is used to evaluate the migration of MA‐srPP in LMW‐hPP towards the interface when contacting a polar sapphire substrate. It shows that the buried interface between the LMW‐hPP/MA‐srPP blend (wt ratio = 80/20) and sapphire has the same characteristic spectrum as the MA‐srPP/sapphire interface, suggesting the enrichment of MA‐srPP in the interfacial polymer when the blend is in contact with sapphire. Also, vibrational modes of C=O have been detected at both the blend/sapphire and MA‐srPP/sapphire interfaces, further indicating that the interfacial polymer contains MA groups. Besides Mylar, adhesion to the non‐polar iPP substrate is also studied. The adhesion mechanisms to these polar and non‐polar substrates are explained in terms of our adhesion model. Applications of these MA functionalized polyolefins and blends are envisioned in the tie‐layer and adhesive areas. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39855.     

马来酸酐接枝PS相容剂的研究

研究了马来酸酐(MAH)在螺杆挤出机中与聚苯乙烯的接枝反应，确定了挤出接枝反应的最佳工艺条件，初步探索了温度、螺杆转速、引发剂浓度以及MAH浓度对接枝反应的影响。     

Synthesis of ultrafine poly(styrene‐maleic anhydride) and polystyrene fibers by electrospinning

Fiber formation from atactic polystyrene (aPS) and alternating poly(styrene‐maleic anhydride) (PSMA) synthesized by free radical polymerization (AIBN, 90°C, 4 h) were investigated by electrospinning from various solutions. aPS was soluble in dimethylformamide (DMF), tetrahydrofuran (THF), toluene, styrene, and benzene, whereas PSMA was soluble in acetone, DMF, THF, dimethylsulfoxide (DMSO), ethyl acetate, and methanol. aPS fibers could be electrospun from 15 to 20% DMF and 20% THF solutions, but not from styrene nor toluene. PSMA, on the other hand, could be efficiently electrospun into fibers from DMF and DMSO at 20 and 25%, respectively. Few PSMA fibers were, however, produced from acetone, THF, or ethyl acetate solutions. Results showed that solvent properties and polymer–solvent miscibility strongly influenced the fiber formation from electrospinning. The addition of solvents, such as THF, generally improved the fiber uniformity and reduced fiber sizes for both polymers. The nonsolvents, however, had opposing effects on the two polymers, i.e., significantly reducing PSMA fiber diameters to 200 to 300 nm, creating larger and irregularly shaped aPS fibers. The ability to incorporate the styrene monomer and divinylbenzene crosslinker in aPS fibers as well as to hydrolyze PSMA fibers with diluted NaOH solutions demonstrated potential for post‐electrospinning reactions and modification of these ultrafine fibers for reactive support materials. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Grafting modification of electrospun polystyrene fibrous membranes via an entrapped initiator in an acrylic acid aqueous solution

Ultrafine electrospun polymer fibers, with their large specific surface areas, have not found wide applications partly because the fiber surfaces usually carry an insufficient quantity of active groups. The electrospinning and surface‐grafting copolymerization of polystyrene fibrous membranes were carried out via the embedded radical initiator approach. The results from X‐ray photoelectron spectroscopy show that the initiator added to the polystyrene dope was deliberately expelled onto the fiber surfaces. The microstructure and hydrophilicity of the grafted membranes were investigated with Fourier transform infrared spectroscopy, scanning electron microscopy, and water contact angle and water uptake capacity measurements. An increase in the initiator dosages led to decreases in the grafting rate, water uptake, and hydrophilicity of the grafted membranes; the opposite was true for increases in the neutralization of acrylic acid (AA). However, the grafting, water uptake, and hydrophilicity of the grafted membranes presented nonlinear relationships with the concentration of AA. The initiator emigration technique will provide a facile and feasible platform for the surface‐grafting modification of electrospun membranes. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of a novel fibrous antibacterial fiber with organophorsphor functional groups

A novel antibacterial fiber named ethyltriphenylphosphonium bromide‐polyacrylonitrile fiber (ETPB‐PANF) was synthesized by chemical modification of PANF reacted with ETPB. The PANF was first immersed in NaOH solution to get Na‐PANF with ? COONa groups. Na‐PANF was then reacted with ETPB to get the final fiber. During the process of synthesis, this article investigated on the initial concentration of ETPB, the contact time, the reaction temperature, and the pH of the solution that may have effect on the properties of ETPB‐PANF. ETPB‐PANF was characterized by Fourier transform infrared spectroscopy, thermo gravimetric analyzer, scanning electron microscope, and X‐ray photoelectron spectroscopy, and the releasing amount of ETPB from ETPB‐PANF was examined by inductively coupled plasma atomic emission spectrometry. The antibacterial activity of ETPB‐PANF was examined against Escherichia coli and Staphylococci aureus by improved shake flask method in sterile saline. The results showed that organophorsphor functional groups have been successfully grafted on PANF, and ETPB‐PANF showed good antibacterial abilities for E. coli and S. aureus. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40935.     

Hypercrosslinked polystyrene microspheres with bimodal pore size distribution and controllable macroporosity

A combination of suspension polymerization and postcrosslinking was used to prepare hypercrosslinked polystyrene (H‐PS) microspheres with controllably bimodal pore size distribution in the presence of toluene and polypropylene (PP) as a coporogen. The proportion of PP in the coporogen was changed to investigate the influence of the coporogen composition on the pore structure of the H‐PS microspheres. The addition of a small amount of PP achieved the aim of a clearly bimodal pore size distribution and the control of the macroporosity of the H‐PS microspheres, which have potential application in the preparation of catalyst supports. The specific surface area of the H‐PS microspheres could be adjusted in the range 380–790 m²/g by changes in the concentration of PP in the coporogen. Moreover, the H‐PS microspheres displayed all the characteristics of Davankov‐type resins by their ability to be swollen in both thermodynamically poor solvents such as water and good solvents such as toluene. Finally, the possible mechanism of porosity formation during polymerization and postcrosslinking was also examined by a combination of pore structure data and the appearance of the microspheres before and after postcrosslinking. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Montmorillonite as support for peroxide in the melt grafting of maleic anhydride onto polypropylene

Grafting of maleic anhydride onto polypropylene was performed in a Haake torque rheometer, in the presence of organically modified montmorillonite, MMT (used as support for the peroxide), according to a 2³ factorial design, where the maleic anhydride concentration (C_MA), peroxide concentration (C_per) and reaction time (t_r) were varied. For comparison, the reaction in the absence of MMT was also conducted. Polypropylene degradation was assessed by parallel plate rheometry and size exclusion chromatography (SEC) and percentage of reacted maleic anhydride (%MA_g) was obtained by titration and FTIR spectroscopy. The results showed differences in both systems, conventional and in the presence of MMT. The structure of polypropylene grafted with maleic anhydride, PP‐g‐MA, indicates longer branches are formed in the presence of MMT compared to in its absence, demonstrated by FTIR analysis. As in conventional reaction systems, an increase in C_per caused an increase in %MA_g and a reduction in molar mass. The variable C_MA showed to be not significant in the grafting reaction in the presence of MMT, even at high DCP levels, at a 5% significance level. On the other hand, increase in C_MA resulted in significant increase in viscosity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44134.     

Multifunctional cotton fabric: Antimicrobial and durable press

2‐Amino‐2‐methyl‐1‐propanol (AMP) was coated onto cotton fabric with 1,2,3,4‐butanetetracarboxylic acid (BTCA) as a crosslinking agent to simultaneously impart antimicrobial and durable‐press functionalities. The coatings were characterized and confirmed by attenuated total reflectance–IR and thermogravimetric analysis. The coated fabrics were rendered biocidal upon exposure to dilute household bleach, and the chlorinated swatches exhibited about 6 log reductions of Escherichia coli O157:H7 and Staphylococcus aureus within 5 min of contact time. A concentration of 1.5 wt % AMP was sufficient to produce this biocidal efficacy. Increasing the BTCA content of the coating improved the wrinkle recovery angle. The coatings were very stable toward repeated laundering, and they exhibited sufficient halogen storage stabilities for industrial applications. A photolytic decomposition was observed when the coatings were exposed to UVA light. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Bulk modification of styrene–butadiene–styrene triblock copolymer with maleic anhydride

The bulk modification of SBS rubber with maleic anhydride in a mixing chamber of a Haake rheomixer was studied. The effect of temperature, maleic anhydride, and benzoyl peroxide concentrations on the grafting efficiency was evaluated. High grafting efficiency was achieved when the ratio of peroxide and maleic anhydride concentration was high. On the other hand, on this condition high insoluble fraction was generated. The addition of a diamine, 4,4′‐diaminediphenylmethane to the reaction mixture minimizes the amount of insoluble polymer. However, the grafted MAH content also decreases. The graft copolymer was characterized by infrared spectroscopy and the grafting extension was determined by titration. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2953–2960, 2002; DOI 10.1002/app.10355     

Preparation of modified polystyrene with maleic anhydride in the presence of different solvents

Polystyrenes (PS's) with different molecular weights were chemically modified with maleic anhydride (MA) with of benzoyl peroxide as an initiator or with a cationic catalyst such as FeCl₃ in chloroform. The effect of the solvents (i.e.; chloroform, benzene, toluene, xylene, and tetrahydrofuran), PS and MA concentration, molecular weight of PS, and type of catalyst used in the chemical modification was studied. The rate of the reaction was different with different solvents because of chain transfer to the solvent. The IR spectra of the modified polystyrene (MPS) existing at the end of the chemical modification were taken to show the presence of a carboxyl group fixed to the aromatic ring of PS. The kinetics of the reaction of MPS with MA were also studied. MPS samples containing ? CO? CH??CH? COOH fragments inside chains were crosslinked, as proven by differential thermal analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Palladium complex embedded crosslinked polystyrene nanofibers as a green and efficient heterogeneous catalyst for coupling reactions

A simple and green chemical modification coupled with electrospinning technique has been developed to incorporate tetrakis(triphenylphosphine)palladium [Pd(PPh₃)₄] inside crosslinked polystyrene nanofibers (Pd@CPS) as an efficient and stable heterogeneous palladium catalyst. The catalytic activities and recyclabilities of the prepared Pd@CPS catalyst have been evaluated by using Suzuki and Heck reactions of various aromatic halides separately with phenylboronic acid and alkenes. The Pd@CPS exhibited high-catalytic activities for the Suzuki and Heck reactions of aromatic iodides to afford the products in excellent yields (coupling yields >88%). The catalytic activities and the nanofiber structure remained essentially unchanged even after recycling for five times. The high activities and stabilities of the prepared Pd@CPS catalyst can be attributed to the ultrafine fiber and embedment of palladium active species inside the nanofibers.     

The effect of maleic anhydride grafting efficiency on the flexural properties of polyethylene composites

Many authors have reported on the property enhancements possible by compounding high density polyethylene (HDPE) with fillers to produce composites. It is accepted that polyethylene combined with materials such as nanoclay or wood flour will not yield favorable properties unless a compatibilizing material is used to form a link. In this work, compatibilized HDPE was produced by grafting maleic anhydride (MA) to its backbone in a twin screw extruder using a peroxide initiated reactive process. Fourier transform infrared spectroscopy (FTIR) was used to examine the effects of varying peroxide and MA levels on the grafting percentage and it was found that a high percentage could be achieved. The gel content of each HDPE‐g‐MA batch was determined and twin bore rheometry analysis was carried out to examine the effects of crosslinking and MA grafting on the melt viscosity. These HDPE‐g‐MA compatibilizers were subsequently compounded with nanoclay and wood flour to produce composites. The composite materials were tested using a three point bending apparatus to determine the flexural modulus and strength and were shown to have favorable mechanical properties when compared with composites containing no compatibilizer. X‐ray diffraction (XRD) was used to examine the effects of grafted MA content on the intercalation and exfoliation levels of nanoclay composites. The results from XRD scans showed that increased intercalation in polymer nanoclay composites was achieved by increasing the grafted MA content. This was confirmed using a scanning electron microscope, where images produced showed increased levels of dispersion and reductions in nanoclay agglomerates. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Functionalization of ethylene–propylene–diene monomer rubber with maleic anhydride in the melt state through high‐shear stress‐induced initiation

The functionalization reactions of ethylene–propylene–diene monomer rubber (EPDM) with maleic anhydride (MAH) in melt state through high‐shear‐stress‐induced initiation by an increase in the screw rotation speed of the twin‐screw extruder and through compounded initiation by the addition of some initiator and an increase in the screw rotation speed were investigated. The results show that, with increasing screw rotation speed and reaction temperature, the percentage grafting and melt flow rate of the functionalized products (EPDM‐g‐MAH) were noticeably increased, and the viscosity‐average molecular weight decreased, which implied that the grafting reaction consisted of the chain scission and grafting reaction of the produced macroradicals with MAH. In the presence of a certain peroxide initiator, the crosslinking reaction during melt extrusion was suppressed by an increase in the screw rotation speed. The percentage grafting of EPDM‐g‐MAH amounted to 1.1%, its melt flow rate was between 0.3 and 4.0 g/10 min, and its gel content was less than 1.0%, depending on the screw rotation speed and reaction temperature. Impact testing and scanning electron microscopy showed that the functionalized product prepared through the high shear stress‐induced initiation had a higher blocking activity with the amide terminated of PA66 than that prepared through the peroxide initiation or through the compound initiation, and the impact strength of the PA66/EPDM blends, improved by the high‐shear‐stress‐induced product was noticeably higher than those of the peroxide‐initiated product or the compound‐initiated one. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Crystallization and dynamic mechanical properties of polypropylene/polystyrene blends modified with maleic anhydride and styrene

Polypropylene (PP)/polystyrene (PS) blends modified with reactive monomers, such as maleic anhydride (MAH) and styrene (St), and in situ formed PP/PS blends were prepared by melting extrusion. The crystallization and melting behavior and the dynamic mechanical properties of the PP/PS blends, including the structure of the grafted copolymer, were investigated with differential scanning calorimetry, dynamic mechanical analysis, and Fourier transform infrared. The results indicated that the addition of MAH hardly influenced the crystallization temperature of PP in the blends, but the addition of MAH and St increased the crystallization temperature of PP in its blends. The blends showed no remarkable variety for the melting temperature, but the shapes of the melting peaks were influenced by the addition of the reactive monomers. In addition, a significant increase in the storage and loss moduli of all the modified PP/PS blends was observed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2038–2045, 2005     

Silica/poly(styrene-alt-maleic anhydride) hybrid particles as a reactive toughener for epoxy resin

Amino-modified silica nanoparticles (SiO₂─NH₂) were first prepared by hydrolytic condensation of tetraethyl orthosilicate and 3-aminopropylmethyldiethoxysilane. Then, organic–inorganic hybrid particles (SiO₂─SMA) were prepared by the amidation reaction between SiO₂─NH₂ and poly(styrene-alt-maleic anhydride) (SMA). Subsequently, SiO₂─SMA particles were employed for modifying bisphenol-A epoxy/anhydride thermoset. Compared with pure cured epoxy, the modified epoxy thermosets with only 1 wt % of SiO₂─SMA particles could achieve a simultaneous toughening and reinforcing performance. The tensile strength, impact strength, and fracture toughness of epoxy thermoset were increased by 14.1, 44.3, and 114.4%, respectively. Moreover, the modification also improved the thermal stability of epoxy thermosets, and the modulus and glass transition temperature of cured resin were not sacrificed. It can be attributed to the rigid structure of SiO₂, as well as the anhydride and carboxyl groups onto the surface of SiO₂─SMA particles participating in the epoxy curing reaction and effectively enhancing the crosslinking density of epoxy thermoset.     

Melt grafting of poly(ethylene‐vinyl acetate) copolymer with maleic anhydride

Poly(ethylene‐vinyl acetate) (EVA) copolymer was melt grafted with maleic anhydride (MAH) in a twin screw extruder in the presence of peroxide. It is confirmed that MAH has been melt grafted on the backbone of EVA by FTIR using the method of hydrolysis. The NMR analysis suggests that the grafting reaction occurs on the tertiary carbon of main chain of EVA other than the methyl moiety of vinyl acetate (VA) group. The incorporation of VA groups onto the matrix shows a competitive effect on the grafting. The existence of VA groups promotes the extent of MAH graft onto EVA; nevertheless, it also weakens the crystallizability of main chain. When the content of peroxide initiator is 0.1 wt % based on the polymer matrix, the grafting degree increases with increasing the concentration of monomer. When the peroxide content is higher than 0.1 wt %, side reactions such as crosslinking or disproportionation will be introduced into this system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 841–846, 2006