Amphiphilic linear–hyperbranched polymer poly(ethylene glycol)–branched polyethylenimine–poly(ϵ‐caprolactone): synthesis,self‐assembly and application as stabilizer of platinum nanoparticles

Amphiphilic linear–hyperbranched polymer poly(ethylene glycol)–branched polyethylenimine–poly(?‐caprolactone) (PEG‐PEI‐PCL) was synthesized by progressively conjugating PEG (one chain) and PCL (multi‐chains) to PEI (hyperbranched architecture) with a yield of 87%. PEG‐PEI‐PCL forms nano‐sized uniform spherical micelles by self‐assembly in water. The micelles had an average diameter of 56 nm determined using dynamic light scattering and 35 nm observed from transmission electron microscopy images. PEG‐PEI‐PCL was used as a stabilizer of platinum nanoparticles (PtNPs) for the first time. The particle diameter of PEG‐PEI‐PCL‐stabilized PtNPs was 7.8 ± 1.4 nm. Amphiphilic (hydrophilic–hydrophilic–hydrophobic) and hyperbranched (linear–hyperbranched–grafted) structures enabled PtNPs to effectively stabilize and disperse in liquid‐phase synthesis. The highly disperse PtNPs in PEG‐PEI‐PCL micelles improved the catalytic activity for the reduction of 4‐nitrophenol with a catalytic yield of near 100%. © 2016 Society of Chemical Industry     

Synthesis from Molecule into 3D Polyamide 6 Microspheres Stacked Polyhedrons via Self‐Assembly

Self‐assembly provides the basis for a procedure used to organize larger objects into regular, 3D microsphere stacked polyhedrons. A novel approach is described for the fabrication of 3D structured micrometer‐scale polyhedrons which are packed with nanosized spheres in the order of 400 nm by in situ polymerization using phase inversion technology. The extended polyhedrons can assemble into decimeter‐level ordered materials. The side length of an individual polyhedron can be effectively tuned from 10 to 100 µm through several ways. This method realizes directly self‐assembly from molecule to regular extended polyhedrons materials. The process is primarily based on in situ anion polymerization of lactam in two‐phase system whose self‐assembly is driven by hydrogen bonds' force and polyethylene glycol stepwise crystallization synergistically. The results suggest that this strategy for self‐assembly can be applied to design nonplanar complex geometric structure materials. In the future, polyhedrons packed with microspheres may be possible to build more complex 3D, self‐assembly device modules for advanced materials.     

Preparation and properties of compatibilized PVC/SMA‐g‐PA6 blends

The morphology and mechanical properties of PVC/SMA‐g‐PA6 blends were investigated in this paper. Graft to polymer SMA‐g‐PA6 was prepared via a solution graft reaction between SMA and PA6. FTIR test evidences the occurrence of the graft reaction between SMA and PA6. DSC analysis shows that SMA‐g‐PA6 has a lower melting point of 187°C, which may result in a decrease in crystallinity of PA6 and thus enable efficient blending of SMA‐g‐PA6 and PVC. Compatibilization was evidenced by the dramatic increase in mechanical properties, the smaller particle size and finer dispersion of PA6 in PVC matrix, and, further, a cocontinuous morphology at 16 wt % SMA‐g‐PA6 content. SMA‐g‐PA6 from the solution graft reaction can toughen and reinforce PVC material. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 432–439, 2004     

Using PA6 as a charring agent in intumescent polypropylene formulations based on carboxylated polypropylene compatibilizer and nano‐montmorillonite synergistic agent

The intumescent fire retardant polypropylene (IFP/PP) filled with ammonium polyphosphate (APP), melamine (M), and PA6 (charring agent) is discussed. Intumescing degree (ID) and the char yield were determined. Only when the three main components of IFR coexist at appropriate proportions, it has optimal ID and higher char yield. The appropriate proportion is PA6 : APP : M = 10 : 10 : 5. A new compatibilizer, carboxylated polypropylene (EPP), was added to PP/PA‐6 blend. Flow tests indicated that the apparent viscosity increased with the addition of EPP, thermal characterization suggested that EPP has reacted with PA6, PA6‐g‐EPP cocrystallized with PA6, and EPP‐g‐PA6 cocrystallized with PP; SEM micrographs illustrated that the presence of EPP improved the compatibility of PP and PA6. All the investigations showed that EPP was an excellent compatibilizer, and it was a true coupling agent for PP/PA6 blends. Using PA6 as a charring agent resulted in the IFR/PP dripping, which deteriorated the flammability properties. The addition of nano‐montmorillonite (nano‐MMT) as a synergistic agent of IFR enabled to overcome the shortcoming. The tensile test testified that the addition of nano‐MMT enhanced the mechanical strength by 44.3%. SEM showed that nano‐MMT improved the compatibility of the composites. It was concluded that the intumescent system with nano‐MMT was an effective flame retardant in improving combustion properties of polypropylene. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 739–746, 2006     

Exploration of the morphological transition phenomenon of polyaniline from microspheres to nanotubes in acid‐free aqueous 1‐propanol solution in a single polymerization process

Polyaniline micro‐ or nanostructures have been widely investigated due to their unique physical and chemical properties. Although several studies have reported the synthesis of polyaniline microspheres and nanotubes, their mechanisms of formation remain controversial. This study reports our observation of the morphological transition of polyaniline from microspheres to nanotubes in a single polymerization process and also tries to propose their mechanisms of formation. The polymerization of aniline monomer in acid‐free aqueous 1‐propanol solutions (1 and 2 mol L^?1) produces polyaniline microspheres and nanotubes at different reaction stages through a morphology transition process with treatment using ultrasound. In the initial reaction stage, Fourier transform infrared spectra indicate that the aniline monomers form phenazine‐like units, producing polyaniline microspheres with an outside diameter of 1–2 µm. The hydrogen bonds between 1‐propanol and polyaniline serve as the driving force for the polyaniline chains to build microspheres. As the reaction continues, observation indicates the microspheres decompose and reform one‐dimensional nanotubes. In this stage, a structure consisting of a head of phenazine‐like units and a tail of acid‐doping para‐linked aniline units develops. The protonation of the para‐linked aniline units provides the driving force for the formation of nanotubes through a self‐curling process. We report here the unique morphology transition of polyaniline from microspheres to nanotubes in a single polymerization process. The results indicate that the structural change of polyaniline leads to this morphological change. The mechanisms of formation of the microspheres and nanotubes in a polymerization process are also well explained. Copyright © 2010 Society of Chemical Industry     

Dispersion polymerization of uniform cross‐linked polystyrene microspheres in butan‐1‐ol

Butan‐1‐ol can be used as the solvent in the synthesis of poly(styrene‐co‐divinylbenzene‐co‐acrylic acid) microspheres by dispersion polymerization of a mixture of styrene, divinylbenzene (DVB), and acrylic acid (AA). Varying the proportion of the crosslinker DVB affects the size distribution and particle morphology profoundly, with 0.5–1.0% w/w producing spherical particles, whereas 2.0% w/w DVB produces irregular, concave morphologies. Varying the amount of AA from 5–7% w/w increases the average diameter of the spherical particles, whereas 9% w/w AA results in ovoid particles with dimpled surface morphology. In an optimized synthesis using 1.0% w/w DVB and 5% AA, uniform polymer microspheres with an average diameter of 0.8 µm and a coefficient of variation (CV) of diameter of 8.2% are produced. The use of a medium‐polarity solvent, such as butan‐1‐ol, as the solvent for dispersion polymerization will facilitate the incorporation of non‐polar moieties, such as organically‐passivated quantum dots, into the polymer during synthesis. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43103.     

Preparation of poly(divinylbenzene‐co‐N‐isopropylacrylamide) microspheres and their hydrogen‐bonding assembly behavior for raspberry‐like core‐corona polymer composite

Narrowdisperse poly(divinylbenzene‐co‐N‐isopropylacrylamide) (poly(DVB‐co‐NIPAM)) functional microspheres with the diameter in the range of 630 nm and 2.58 μm were prepared by distillation–precipitation polymerization in neat acetonitrile in the absence of any stabilizer. The effect of N‐isopropylacrylamide (NIPAM) ratio in the comonomer feed on the morphology of the resultant polymer particles was investigated in detail with divinylbenzene (DVB) as crosslinker and 2,2′‐azobisisobutyronitrile (AIBN) as initiator. The monodisperse poly(DVB‐co‐NIPAM) microspheres with NIPAM fraction of 20 wt % were selected for the preparation of raspberry‐like core‐corona polymer composite by the hydrogen‐bonding self‐assembly heterocoagulation with poly(ethyleneglycol dimethacrylate‐co‐acrylic acid) [poly(EGDMA‐co‐AA)] nanospheres. Both of the functional poly(DVB‐co‐NIPAM) microspheres and the core‐corona particles were characterized with scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), and elemental analysis (EA). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1350–1357, 2007     

Effect of composition on morphology structure and cell affinity of poly(caprolactone‐co‐glycolide)‐co‐poly(ethylene glycol) microspheres

Poly(caprolactone‐co‐glycolide)‐co‐poly(ethylene gylcol) copolymers (PCEG) with various composition were synthesized by copolymerization of GA, CL, and PEG. PCEG microspheres were fabricated by oil‐in‐water (o/w) emulsion and solvent‐evaporation technique. Effect of chemical composition on hydrophilicity, crystallinity, and degradation of the PCEG was investigated. It was demonstrated that morphology structure of the microspheres was greatly influenced by chemical composition and hydrophilicity of the PCEG polymer. PCEG microspheres could change from a smooth structure to a regular porous structure and an irregular structure. Moreover, the pore size of them increased with increment of PEG content and length. Cell attachment and growth on the PCEG microspheres were evaluated by using mouse NIH 3T3 fibroblasts as model cells in vitro. The result showed that the PCEG microspheres with large porous structure were more favorable for cell attachment and growth. Thus the PCEG microspheres with rapid degradation rate and large porous structure possess potential use as injectable scaffolds in tissue engineering. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42861.     

Flame‐retardant finishing in cotton fabrics using zinc oxide co‐catalyst

In this article, N‐Methylol dimethylphosphonopropionamide (FR) in combination with a melamine resin (CL), phosphoric acid (PA) catalyst and zinc oxide (ZnO) or nano‐ZnO co‐catalyst were used (FR‐CL‐PA‐ZnO or nano‐ZnO system) to impart flame‐retardant property on cotton fabrics. FR‐CL or FR‐CL‐PA‐treated cotton specimen showed roughened and wrinkled fabric surface morphology, which was caused by the attack of the FR with slightly acidity. In addition, FTIR analysis showed some new characteristic peaks, carbonyl, CH₂ rocking and CH₃ asymmetric and CH₂ symmetric stretching bands, in the chemical structure of treated cotton specimens. Apart from these, the flame ignited on the flame‐retardant‐treated fabrics (without subjected to any post‐wet treatment) extinguished right after the removal of ignition source. However, FR‐CL treated specimens were no longer flame‐resistant when the specimens subjected to neutralization and/or home laundering, while FR‐CL‐PA treated specimens showed opposite results. By using 0.2% and 0.4% of ZnO or nano‐ZnO as co‐catalyst, the flame spread rate of neutralized and/or laundered test specimens decreased, even the specimens were undergone 10 home laundering cycles. Moreover, flame‐retardant‐treated cotton specimens had low breaking load and tearing strength resulting from side effects of the crosslinking agent used, while addition of ZnO or nano‐ZnO co‐catalyst could compensates for the reduction. Furthermore, the free formaldehyde content was dropped when ZnO and nano‐ZnO co‐catalyst was added in the treatment. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

A new macroinitiator for the synthesis of triblock copolymers PA12‐b‐PDMS‐b‐PA12

A new PDMS macroinitiator is proposed for the anionic ring‐opening polymerization of lactams. This α,ω‐dicarbamoyloxy caprolactam PDMS macroinitiator was readily obtained in quantitative yield, by an original synthesis scheme in two steps, which involved the scarcely reported reaction of isocyanates with silanol groups. It was then shown that this bifunctional macroinitiator enabled to synthesize triblock copolymers PA12‐b‐PDMS‐b‐PA12 by polymerization of lauryl lactam (LL) at high temperature (200°C) in inert atmosphere under conditions compatible with reactive extrusion processes. Another related high molar weight α,ω‐diacyllactam PDMS macroinitiator was also successfully used in the polymerization of LL under the same conditions, therefore overcoming the limitations formerly reported for this type of macroinitiators during the polymerization ε‐caprolactam (ε‐CL) at a much lower temperature (80°C). Triblock copolymers with a wide range of PA12 /molar weights (M_n: ～ 10,800–250,000 Da) were eventually obtained by using both types of macroinitiators. DMTA and DSC analyses showed that their thermal properties were strongly dependent upon their respective contents in soft and hard blocks. Such triblock copolymers already appear very promising for the highly effective in situ compatibilization of PA12/PDMS blends as shown by recent complementary results obtained in our laboratory. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 2818–2831, 2006     

Anionic polymerization of lactams: A comparative study on various methods of measuring the conversion of ε‐caprolactam to polyamide 6

Anionic ring‐opening polymerization of lactams leads to the formation of poly(lactams) or polyamides. This work aimed at comparing the performance of four methods for measuring the conversion of ε‐caprolactam (CL) to polyamide 6. The latter was either a homopolymer (PA6) or grafts onto polystyrene (PS‐g‐PA6 graft copolymer). Those four methods were mass balance based on solvent extraction (methanol, water, THF, or acetone), mass balance based on vacuum drying at 140°C, thermogravimetric analysis (TGA), and elemental analysis based on nitrogen. The mass balances based on methanol extraction and vacuum drying at 140°C and TGA were all suitable for measuring the conversion of CL, whether the resulting polymer was the PA6 or PS‐g‐PA6. The mass balance based on water extraction was good for the PA6 and not good for the PS‐g‐PA6. The elemental analysis based on nitrogen was not suitable for the PA6 nor for the PS‐g‐PA6. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1972–1981, 2006     

Effect of core‐shell morphology evolution on the rheology,crystallization, and mechanical properties of PA6/EPDM‐g‐MA/HDPE ternary blend

In this article, polyamide 6 (PA6), maleic anhydride grafted ethylene‐propylene‐diene monomer (EPDM‐g‐MA), high‐density polyethylene (HDPE) were simultaneously added into an internal mixer to melt‐mixing for different periods. The relationship between morphology and rheological behaviors, crystallization, mechanical properties of PA6/EPDM‐g‐MA/HDPE blends were studied. The phase morphology observation revealed that PA6/EPDM‐g‐MA/HDPE (70/15/15 wt %) blend is constituted from PA6 matrix in which is dispersed core‐shell droplets of HDPE core encapsulated by EPDM‐g‐MA phase and indicated that the mixing time played a crucial role on the evolution of the core‐shell morphology. Rheological measurement manifested that the complex viscosity and storage modulus of ternary blends were notable higher than the pure polymer blends and binary blends which ascribed different phase morphology. Moreover, the maximum notched impact strength of PA6/EPDM‐g‐MA/HDPE blend was 80.7 KJ/m² and this value was 10–11 times higher than that of pure PA6. Particularly, differential scanning calorimetry results indicated that the bulk crystallization temperature of HDPE (114.6°C) was partly weakened and a new crystallization peak appeared at a lower temperature of around 102.2°C as a result of co‐crystal of HDPE and EPDM‐g‐MA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Novel blend microspheres of poly(3‐hydroxybutyrate) and Pluronic F68/127 for controlled release of 6‐mercaptopurine

The objective of this article is to investigate the controlled release characteristics of 6‐mercaptopurine (6‐MP) loaded microspheres prepared from the blends of poly(3‐hydroxybutyrate) (PHB) and Pluronic F68/127 by the oil‐in‐water emulsion‐solvent evaporation technique. Formulations were prepared by taking different ratios of individual polymer components to achieve a maximum 79% encapsulation and extending the release time up to 24 h. Differential scanning calorimetry (DSC) suggested reduction in crystallanity of PHB after blending with Pluronic F127. The absence of chemical interactions between 6‐MP and the blend matrix was confirmed by Fourier transform infrared (FTIR) spectroscopy, while the size of microspheres measured by optical microscopy ranged between 30 and 47 μm. X‐ray diffraction (XRD) confirmed the crystalline nature of 6‐MP even after encapsulation and surface morphology of the microspheres was investigated by scanning electron microscopy (SEM). In vitro release of 6‐MP at 37°C in pH 7.4 phosphate buffer media indicated a dependence on the composition of Pluronic in the blend. The release data have been fitted to empirical equations to understand the release profile of 6‐MP. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40196.     

Heparin‐immobilized poly(2‐hydroxyethylmethacrylate)‐based microspheres

Poly(2‐hydroxyethylmethacrylate) (PHEMA)‐based microspheres (150–200 µm in diameter) were produced by a modified suspension polymerization of different type of comonomers—namely, acrylic acid, dimethylaminoethyl‐methacrylate, and methylmethacrylate. These microspheres were activated with cyanogen bromide (CNBr) at pH 11.5, and heparin molecules were then immobilized through covalent bonds. The amount of immobilized heparin was controlled by changing the initial concentration of CNBr and heparin. The increase in the initial concentrations of both CNBr and heparin caused an increase in the amount of heparin immobilized onto microspheres for all polymer surfaces. The maximum heparin immobilization was observed on the PHEMA homopolymer microspheres (180 mg/g). The plain and heparin‐immobilized microspheres were contacted with blood in in vitro systems and in ex vivo animal experiments. Loss of the blood cells and clotting times were followed. Anticoagulant effect of the immobilized heparin was clearly observed with blood coagulation experiments. Loss of cells in the blood contacting with heparin‐immobilized microspheres was significantly lower than those observed with the plain microspheres. Bovine serum albumin adsorption onto the microspheres containing heparin on their surfaces was also studied. High albumin adsorption values (up to 127 mg/g) were observed in which the heparin‐immobilized PHEMA microspheres were used. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 655–662, 1999     

Polyamide 6/ethylene‐butylene elastomer blends generated via anionic polymerization of ε‐caprolactam: Phase morphology and dynamic mechanical behavior

This paper reports about the polymerization of ε‐caprolactam monomer in the presence of low molecular weight hydroxyl or isocyanate end‐capped ethylene‐butylene elastomer (EB) elastomers as a new concept for the development of a submicron phase morphology in polyamide 6 (PA6)/EB blends. The phase morphology, viscoelastic behavior, and impact strength of the polymerization‐designed blends are compared to those of similar blends prepared via melt‐extrusion of PA6 homopolymer and EB elastomer. Polyamide 6 and EB elastomer were compatibilized using a premade triblock copolymer PA6‐b‐EB‐b‐PA6 or a pure EB‐b‐PA6 diblock reactively generated during melt‐blending (extrusion‐prepared blends) or built‐up via anionic polymerization of ε‐caprolactam on initiating ? NCO groups attached to EB chain ends (polymerization‐prepared blends). Two compatibilization approaches were considered for the polymerization‐prepared blends: (i) the addition of a premade PA6‐b‐EB‐b‐PA6 triblock copolymer to the ε‐caprolactam monomer containing nonreactive EB? OH elastomer and (ii) generation in situ of a PA6‐b‐EB diblock using EB? NCO precursor on which polyamide 6 blocks are built‐up via anionic polymerization of ε‐caprolactam. The noncompatibilized blends exhibit a coarse phase morphology, either in the extruded or the polymerization prepared blends. Addition of premade triblock copolymer (PA6‐b‐EB‐b‐PA6) to a EB? OH /ε‐caprolactam dispersion led to a fine EB phase (0.14 μm) in the PA6 matrix after ε‐caprolactam polymerization. The average particle size of the in situ reactively compatibilized polymerization‐prepared blend is about 1 μm. The notched Izod impact strength of the blend compatibilized with premade triblock copolymer was much higher than that of the neat PA6, the noncompatibilized, and the in situ reactively compatibilized polymerization blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2538–2544, 2004     

Microcompounding of organoclay–ABS/PA6 blend‐based nanocomposites

In this study, acrylonitrile–butadiene–styrene (ABS) and polyamide‐6 (PA6) were blended in the presence of an olefin‐based compatibilizer and organoclays. The effects of ABS to PA6 ratio, clay content, and screw speed of the microcompounder were examined by performing morphological (i.e., XRD, SEM, and TEM) and tensile tests. The average aspect ratio of the clay platelets after processing was obtained by applying semiautomatic image analysis method. SEM analysis showed that addition of the compatibilizers to the ABS/PA6 blend system resulted in a decrease in diameter of dispersed phase when one of the phases was continuous. The addition of 5 wt% compatibilizer altered the dispersed morphology to cocontinuous morphology when the weight percentage of ABS was equal to that of PA6. The results of XRD analysis implied that clays were exfoliated in the presence of PA6. It was observed in TEM micrographs that clays were selectively dispersed in PA6 phase. Aspect ratio of the platelets increased as the PA6 content increased. Moduli of the nanocomposites were improved by enriching blend with PA6 and increasing screw speed. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Synthesis and characterization of advance PA6‐b‐PDMS multiblock copolymers

Advance polyamide‐6‐b‐polydimethylsiloxane (PA6‐b‐PDMS) multiblock copolymers were first synthesized via the polymerization in bulk. Binary carboxyl terminated PA6 was served as the hard segment and PDMS modified with hexamethylene diisocyanate (PDMS‐NCO) was the soft segment. A series of PA6‐b‐PDMS copolymers based on different content and length of soft segments were obtained. Interestingly, Differential scanning calorimetry (DSC) studies revealed no obvious change in melting temperature after introducing PDMS segments to copolymers. The high melting temperatures indicated these copolymers possess potential applications in automotive industry that require high continuous use temperatures. DSC and transmission electron microscopy studies both demonstrated increasing the length and the content of the soft segment contributed to increasing of the degree of microphase separation. However, the improvement of thermal stability resulting from PDMS segments was also observed by thermo gravimetric analysis. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41114.     

Enhanced mechanical properties of multilayer nano‐coated electrospun nylon 6 fibers via a layer‐by‐layer self‐assembly

We reported the mechanical properties of the polyelectrolyte multilayer nano‐coated electrospun fiber mats with different number of layers. Multilayer nano‐coatings composed of layers of PSS and PAH were successfully deposited onto electrospun nylon 6 fibers via layer‐by‐layer self‐assembly. Compared with pure nylon 6 fibers, the morphology of polyelectrolyte multilayer coated nylon 6 fibers was uniform and smooth. The mechanical properties of polyelectrolyte multilayer coated random and aligned nylon 6 fibers were remarkably enhanced. Moreover, it was found that the higher degree of alignment resulted in higher tensile strength, suggesting the combined effects of the alignment, the surface nanocoating and the formation of internal networks of polyelectrolytes on nylone 6 fibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

One‐pot synthesis of self‐stabilized and carboxyl‐functionalized fluorescent poly(methyl methacrylate) microspheres covalently dyed with tris(8‐hydroquinolinato)aluminium by dispersion polymerization

The dispersion polymerization of methyl methacrylate (MMA) with fluorescent monomer tris[2‐((8‐hydroxyquinolin‐5‐yl)methoxy)ethyl methacrylate]aluminium (Al‐HQHEMA) was investigated to obtain fluorescent microspheres under varying conditions (such as composition of dispersion medium, and content of stabilizer polyvinylpyrrolidone (PVP) and Al‐HQHEMA) in methanol–water at 70 °C with 2,2′‐azoisobutyronitrile as the initiator. Fluorescent microspheres with particle size of 2.039 µm and uniformity of 0.171 were obtained under the following conditions: methanol–water, 7:3 (v/v); PVP, 15 wt% of MMA; Al‐HQHEMA solution, 1.5 mL. Maleic monoester of monomethoxyl poly(ethylene glycol) (Mal‐MPEG) was used as a comonomer to simultaneously incorporate carboxyl groups and PEG chains. With Mal‐MPEG, no aggregation was observed in the measurements of particle size and size distribution for the obtained microspheres after cleaning off PVP, indicating that self‐stabilized fluorescent microspheres were obtained. While without Mal‐MPEG, obvious aggregation was observed. The determination of surface carboxyl content using aqueous acid–base titration showed that most of the carboxyl groups of Mal‐MPEG were located on the surface of the microspheres. © 2015 Society of Chemical Industry     

Fractionated crystallization of dispersed PA6 phase of PP/PP‐g‐MAH/PA6 blends

Fractionated crystallization behavior of dispersed PA6 phase in PP/PA6 blends compatibilized with PP‐g‐MAH was investigated by scanning electron microscopy (SEM), differential scanning calorimeter (DSC), polarized light microscopy (PLM), and wide‐angle X‐ray diffraction (WAXD) in this work. The lack of usual active heterogeneities in the dispersed droplet was the key factor for the fractionated crystallization of PA6. The crystals formed with less efficient nuclei might contain more defects in the crystal structures than those crystallized with the usual active nuclei. The lower the crystallization temperature, the lesser the perfection of the crystals and the lower crystallinity would be. The fractionated crystallization of PP droplets encapsulated by PA6 domains was also observed. The effect of existing PP‐g‐MAH‐g‐PA6 copolymer located at the interface on the fractionated crystallization could not be detected in this work. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3742–3755, 2004