Morphology and mechanical properties of natural rubber latex films modified by exfoliated Na‐montmorillonite/polyethyleneimine‐g‐poly (methyl methacrylate) nanocomposites

Na‐montmorillonite/polyethyleneimine‐g‐poly(methyl methacrylate) (Na‐MMT/PEI‐g‐PMMA) nanocomposite latexes were prepared by soap‐free emulsion polymerization in the aqueous suspension of Na‐MMT. The exfoliated morphology of the nanocomposites was confirmed by XRD and TEM. With the aim of improving morphology and mechanical properties of natural rubber latex (NRL) films, the synthesized Na‐MMT/PEI‐g‐PMMA nanocomposites were mixed with NRL by latex compounding technology. The results of SEM and AFM analysis showed that the surface of NRL/Na‐MMT/PEI‐g‐PMMA film was smoother and denser than that of pristine NRL film while Na‐MMT was dispersed uniformly on the fracture surface of the modified films, which suggested the good compatibility between NRL and Na‐MMT/PEI‐g‐PMMA. The tensile strength of NRL/Na‐MMT/PEI‐g‐PMMA films was increased greatly by 85% with 10 phr Na‐MMT/PEI‐g‐PMMA when Na‐MMT content was 3 wt % and the elongation at break also increased from 930% to 1073% at the same time. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43961.     

Acetylsalicylic acid loading and release studies of the PMMA‐g‐polymeric oils/oily acids micro and nanospheres

Poly(methyl methacrylate) (PMMA) and PMMA copolymers derived from plant oils (Polylinseed oil‐g‐PMMA, Polysoybean oil‐g‐PMMA, Polylinoleic acid‐g‐PMMA (PLina‐g‐PMMA) and Polyhydroxy alkanoate‐ sy‐g‐Polylinoleic acid‐g‐PMMA (PHA‐g‐PLina‐g‐PMMA)) as hydrophobic polymers, a series of hydrophobic microsphere or nanosphere dispersions, were prepared by the emulsion/solvent evaporation method. The diameters of the nanospheres and microspheres were measured by dynamic light scattering with a zetasizer, optically and by scanning electron microscopy. The magnetic quality of the microspheres was determined by the electron spin resonance technique. Acetylsalicylic acid (aspirin, ASA) was used as a model drug and loaded into the microspheres during the preparation process. The effect of the stirring rate over the size and size distribution of the micro/nanospheres was evaluated, and the effects of copolymer types derived from plant oil/oily acids and the copolymer/drug ratios were evaluated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Gelatin‐g‐poly(methyl methacrylate)/silver nanoparticle hybrid films and the evaluation of their antibacterial activity

We designed and prepared novel hybrid films of nanoparticles consisting of gelatin‐g‐poly(methyl methacrylate) (PMMA)/silver (Ag) polymers with ordered nanoporous, higher antibacterial activities. First, the gelatin‐grafted PMMA microspheres were fabricated with the in situ copolymerization of gelatin and alkenes under radical initiation, which acted as a stabilizer and regulator for Ag nanoparticle growth. Then, silver nitrate was entrapped in a copolymerization system at 40°C for 30 min. Finally, the gelatin‐g‐PMMA/Ag polymer hybrid films were prepared by the reduction of Ag⁺ with hydrazine, followed by emulsion solidification. The antibacterial activities of the gelatin‐g‐PMMA/Ag polymer hybrid films against Escherichia coli and Staphylococcus aureus were found with the disc diffusion method and colony count assays to be clear and lasting. In this study, our work not only presented a good example of a nanoporous antibacterial film material but also provided a facile method for making use of gelatin and metal/inorganic self‐assemble properties in graft copolymerization to prepare functional polymer hybrids, such as antibacterial, antithrombogenic, and dot‐quantum effect materials. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Polyethylenimine‐grafted and HSA‐immobilized poly(GMA–MMA) affinity adsorbents for bilirubin removal

The epoxy‐group‐containing microspheres from cross‐linked glycidyl methacrylate and methyl methacrylate, poly(GMA–MMA), were prepared by suspension polymerisation. The epoxy groups of the poly(GMA–MMA) microspheres were used for grafting with an anionic polymer polyethylenimine (PEI) to prepare non‐specific affinity adsorbents (poly(GMA–MMA)–PEI) for bilirubin removal. The specificity of the poly(GMA–MMA)–PEI adsorbent to bilirubin was further increased by immobilization of human serum albumin (HSA) via adsorption onto PEI‐grafted poly(GMA–MMA) adsorbent. Various amounts of HSA were immobilized on the poly(GMA–MMA)–PEI adsorbent by changing the medium pH and initial HSA concentration. The maximum HSA content was obtained at 68.3 mg g^?1 microspheres. The effects of pH, ionic strength, temperature and initial bilirubin concentration on the adsorption capacity of both adsorbents were investigated in a batch system. Separation of bilirubin from human serum was also investigated in a continuous‐flow system. The bilirubin adsorption on the poly(GMA–MMA)–PEI and poly(GMA–MMA)–PEI–HSA was not well described by the Langmuir model, but obeyed the Freundlich isotherm model. The poly(GMA–MMA)–PEI affinity microspheres are stable when subjected to sanitization with sodium hydroxide after repeated adsorption–desorption cycles. Copyright © 2004 Society of Chemical Industry     

DOPO‐Based Phosphorus‐Containing Methacrylic (Co)Polymers: Glass Transition Temperature Investigation

A two‐step synthetic procedure is designed for preparing new flame‐retardant methacrylic monomers containing 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) as a substituent side group. DOPO and methacrylate moieties are linked by linear aliphatic hydrocarbon spacers (3 to 11 carbon atoms). Copolymerization with methyl methacrylate is carried out leading to copolymers containing between 2 and 10 wt% phosphorus. All homo‐ and copolymers exhibit a unique glass transition temperature (T_g ). A new group contribution for DOPO‐based substituent is extracted that leads to reasonable estimations of T_g s of other published polymers. The Fox equation provides a good estimation of T_g s for most copolymers and for physical blends of poly(methyl methacrylate) (PMMA) and DOPO. When using monomers having three and four carbon atoms in the hydrocarbon spacer, the T_g of copolymers remains close to that of PMMA over a wide range of composition.     

Polymerization of methyl methacrylate with a thermal iniferter: Diethyl 2,3‐dicyano‐2,3‐di(p‐tolyl)succinate

A hexa‐substituted ethane type compound, diethyl‐2,3‐dicyano‐2,3‐di(p‐tolyl)succinate (DCDTS), was successfully synthesized and used for initiation of methyl methacrylate (MMA) polymerization. The reaction demonstrated the characteristics of a “living” polymerization; i.e., both the yield and the molecular weight of the resulting polymers increased linearly with increasing reaction time, the molecular‐weight distribution of PMMA obtained was ～1.60 and almost unaffected by the conversion, and the resultant polymer can be chain extended by adding fresh MMA. End group analysis of the resultant PMMA confirmed that DCDTS behaves as a thermal iniferter for MMA polymerization. A block copolymer was prepared from the resultant PMMA, which contains a hexa‐substituted C? C bond functional end group. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2566–2572, 2001     

Effect of in situ polymerization conditions of methyl methacrylate on the structural and morphological properties of poly(methyl methacrylate)/poly(acrylonitrile‐g‐(ethylene‐co‐propylene‐co‐diene)‐g‐styrene) PMMA/AES Blends

In this study, the structural and morphological properties of poly(methyl methacrylate)/poly(acrylonitrile‐g‐(ethylene‐co‐propylene‐co‐diene‐g‐styrene) (PMMA‐AES) blends were investigated with emphasis on the influence of the in situ polymerization conditions of methyl methacrylate. PMMA‐AES blends were obtained by in situ polymerization, varying the solvent (chloroform or toluene) and polymerization conditions: method A—no stirring and air atmosphere; method B—stirring and N₂ atmosphere. The blends were characterized by infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and dynamic mechanical analysis (DMA). The results showed that the PMMA‐AES blends are immiscible and present complex morphologies. This morphology shows an elastomeric dispersed phase in a glassy matrix, with inclusion of the matrix in the elastomer domains, suggesting core shell or salami morphology. The occlusion of the glassy phase within the elastomeric domains can be due to the formation of graft copolymer and/or phase inversion during polymerization. However, this morphology is affected by the polymerization conditions (stirring and air or N₂ atmosphere) and by the solvent used. The selective extraction of the blends' components and infrared spectroscopy showed that crosslinked and/or grafting reactions occur on the elastomer chains during MMA polymerization. The glass transition of the elastomer phase is influenced by morphology, crosslinking, and grafting degree and, therefore, T_g depends on the polymerization conditions. On the other hand, the behavior of T_g of the glassy phase with blend composition suggests miscibility or partial miscibility for the SAN phase of AES and PMMA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

The synthesis of poly(3‐hydroxybutyrate)‐g‐poly(methylmethacrylate) brush type graft copolymers by atom transfer radical polymerization method

Brush type of poly (3‐hydroxy butyrate), PHB, copolymer synthesis has been reported. Natural PHB was chlorinated by passing chlorine gas through PHB solution in CHCl₃/CCl₄ mixture (75/25 v/v) to prepare chlorinated PHB, PHB‐Cl, with the chlorine contents varying between 2.18 and 39.8 wt %. Toluene solution of PHB‐Cl was used in the atom transfer radical polymerization (ATRP) of methyl methacrylate, MMA, in the presence of cuprous bromide (CuBr)/2,2′‐bipyridine complex as catalyst, at 90°C. This “grafting from” technique led to obtain poly (3‐hydroxybutyrate)‐g‐poly(methylmethacrylate) (PHB‐g‐PMMA) brush type graft copolymers (cylindrical brush). The polymer brushes were fractionated by fractional precipitation methods and the γ values calculated from the ratio of the volume of nonsolvent to volume of solvent of brushes were ranged between 2.8 and 9.5 depending on the molecular weight, grafting density, and side chain length of the brushes, while the γ values of PHB, PHB‐Cl, and homo‐PMMA were 2.7–3.8, 0.3–2.4, and 3.0–3.9, respectively. The fractionated brushes were characterized by gel permeation chromatography, ¹H‐NMR spectrometry, thermogravimetric analysis (TGA), and differential scanning calorimetry techniques. PHB‐g‐PMMA brush type graft copolymers showed narrower molecular weight distribution (mostly in range between 1.3 and 2.2) than the PHB‐Cl macroinitiator (1.6–3.5). PHB contents in the brushes were calculated from their TGA thermograms and found to be in range between 22 and 42 mol %. The morphologies of PHB‐g‐PMMA brushes were also studied by scanning electron microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Surface‐initiated atom transfer radical polymerization from Mg(OH)2 nanoparticles to prepare the well‐defined polymer‐Mg(OH)2 nanocomposites

Well‐defined polymer‐Mg(OH)₂ nanocomposites were prepared by atom transfer radical polymerization (ATRP). The ATRP initiators were covalently attached to the Mg(OH)₂ by esterification of 2‐chloropropionyl chloride with hydroxyl group. The amount of polymer grafted from Mg(OH)₂ can be controlled using a different catalyst system and adding a small amount of polar solvent. The well‐defined diblock copolymer, consisting of poly(styrene) (PS) and poly(methyl methacrylate) (PMMA) were synthesized. The products were characterized by nuclear magnetic resonance, Fourier transform infrared, differential scanning calorimetry, and thermal gravimetric analysis. The morphologies of PS/PMMA and PS/PMMA/Mg(OH)₂‐g‐PS‐b‐PMMA blends are compared by using a scanning electron microscope. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3680–3687, 2007     

Fabrication of poly(methyl methacrylate)‐block‐poly(N‐isopropylacrylamide) amphiphilic diblock copolymer on silicon substrates via surface‐initiated reverse iodine transfer polymerization

Amphiphilic diblock copolymer on silicon substrates were synthesized via surface‐initiated reverse iodine transfer polymerization (RITP) technique. The silicon substrates (Si (111) surface) were modified with the azo groups, which were introduced by the treatment of Si (111) surface with 4,4′‐azobis (4‐cyanopentanoic acid). The poly(methyl methacrylate) (PMMA) were then prepared under RITP conditions from the Si (111) wafer. The synthesis of amphiphilic diblock copolymer was carried out on Si‐g‐PMMA substrate by sequential addition of monomer N‐isopropylacrylamide (NIPAM). The observed narrow molecular weight distributions (M_w/M_n), linear kinetic plots, and linear plots of molecular weight (M_n) versus monomer conversion indicate that the chain growth from the silicon substrates is a controlled process with a “living” characteristic. The ellipsometry and contact angle results indicated that the MMA had grafted from the surface of the silicon substrates successfully and the graft layer was well defined. The structure of the polymer and the ability to extend the chains were characterized and confirmed with the surface sensitive techniques such as X‐ray photoelectron spectroscopy and atomic force microscope. POLYM. ENG. SCI., 54:925–931, 2014. © 2013 Society of Plastics Engineers     

Poly(methyl methacrylate)‐grafted cellulose nanocrystals: One‐step synthesis,nanocomposite preparation,and characterization

Cellulose nanocrystals (CNCs) are ideal reinforcing agents for polymer nanocomposites because they are lightweight and nano‐sized with a large aspect ratio and high elastic modulus. To overcome the poor compatibility of hydrophilic CNCs in non‐polar composite matrices, we grafted poly(methyl methacrylate) (PMMA) from the surface of CNCs using an aqueous, one‐pot, free radical polymerization method with ceric ammonium nitrate as the initiator. The hybrid nanoparticles were characterized by CP/MAS NMR, X‐ray photoelectron spectroscopy, infrared spectroscopy, contact angle, thermogravimetric analysis, X‐ray diffraction, and atomic force microscopy. Spectroscopy demonstrates that 0.11 g/g (11 wt %) PMMA is grafted from the CNC surface, giving PMMA‐g‐CNCs, which are similar in size and crystallinity to unmodified CNCs but have an onset of thermal degradation 45 °C lower. Nanocomposites were prepared by compounding unmodified CNCs and PMMA‐g‐CNCs (0.0025–0.02 g/g (0.25–2 wt %) loading) with PMMA using melt mixing and wet ball milling. CNCs improved the performance of melt‐mixed nanocomposites at 0.02 g/g (2 wt %) loading compared to the PMMA control, while lower loadings of CNCs and all loadings of PMMA‐g‐CNCs did not. The difference in Young's modulus between unmodified CNC and polymer‐grafted CNC composites was generally insignificant. Overall, ball‐milled composites had inferior mechanical and rheological properties compared to melt‐mixed composites. Scanning electron microscopy showed aggregation in the samples with CNCs, but more pronounced aggregation with PMMA‐g‐CNCs. Despite improving interfacial compatibility between the nanoparticles and the matrix, the effect of PMMA‐g‐CNC aggregation and decreased thermal stability dominated the composite performance.     

Synthesis of PMMA‐PTHF‐PMMA and PMMA‐PTHF‐PST linear and star block copolymers

Combination of cationic, redox free radical, and thermal free radical polymerizations was performed to obtain linear and star polytetramethylene oxide (poly‐THF)‐polymethyl methacrylate (PMMA)/polystyrene (PSt) multiblock copolymers. Cationic polymerization of THF was initiated by the mixture of AgSbF₆ and bis(4,4′ bromo‐methyl benzoyl) peroxide (BBP) or bis (3,5,3′,5′ dibromomethyl benzoyl) peroxide (BDBP) at 20°C to obtain linear and star poly‐THF initiators with M_w varying from 7,500 to 59,000 Da. Poly‐THF samples with hydroxyl ends were used in the methyl methacrylate (MMA) polymerization in the presence of Ce(IV) salt at 40°C to obtain poly(THF‐b‐MMA) block copolymers containing the peroxide group in the middle. Poly(MMA‐b‐THF) linear and star block copolymers having the peroxide group in the chain were used in the polymerization of methyl methacrylate (MMA) and styrene (St) at 80°C to obtain PMMA‐b‐PTHF‐b‐PMMA and PMMA‐b‐PTHF‐b‐PSt linear and star multiblock copolymers. Polymers obtained were characterizated by GPC, FT‐IR, DSC, TGA, ¹H‐NMR, and ¹³C‐NMR techniques and the fractional precipitation method. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 219–226, 2004     

Synthesis of poly(methyl methacrylate‐g‐glycidyl azide) graft copolymers using N,N‐dithiocarbamate‐mediated iniferters

A glycidyl azide polymer with pendent N, N‐diethyl dithiocarbamate groups (GAP‐DDC) was prepared by the reaction of poly(epichlorohydrin) (PECH) with pendent N, N‐diethyl dithiocarbamate groups (PECH‐DDC) and sodium azide (NaN₃) in dimethylformamide (DMF). It was then used as a macro‐photoinitiator for the graft polymerization of methyl methacrylate (MMA). Photopolymerization was carried out in a photochemical reactor at a wavelength greater than 300 nm. Conversion was determined gravimetrically and first‐order time conversion plot for the polymerization system showed linear increase with the polymerization time indicating that polymerization proceed in controlled fashion. The molecular weight distribution (M_w/M_n) was in the range of 1.4–1.6 during polymerization. The formation of poly(methyl methacrylate‐g‐glycidyl azide) (PMMA‐g‐GAP) graft copolymer was characterized by gel permeation chromatography, FT‐IR spectroscopy, Thermogravimetric analysis, and differential scanning calorimetry. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Rheological and thermal properties of thermoplastic natural rubbers based on poly(methyl methacrylate)/epoxidized‐natural‐rubber blends

Epoxidized natural rubbers (ENRs) with epoxide levels of 10, 20, 30, 40, and 50 mol % were prepared. The ENRs were later blended with poly(methyl methacrylate) (PMMA) with various blend formulations. The mixing torque of the blends was observed. The torque increased as the PMMA contents and epoxide molar percentage increased in the ENR molecules. Furthermore, the shear stress and shear viscosity of the polymer blends in the molten state increased as the ENR content and epoxide molar percentage increased in the ENR molecules. Chemical interactions between polar groups in the ENR and PMMA molecules might be the reason for the increases in the torque, shear stress, and viscosity. All the ENR/PMMA blends exhibited shear‐thinning behavior. This was observed as a decrease in the shear viscosity with an increase in the shear rate. The power‐law index of the blends decreased as the ENR contents and epoxide molar percentage increased in the ENR molecules. However, the consistency index (or zero shear viscosity) increased as the ENR contents and epoxide molar percentage increased. A two‐phase morphology was observed with scanning electron microscopy. The small domains of the minor components were dispersed in the major phase. For the determination of blend compatibility, two distinct glass‐transition‐temperature (T_g) peaks from the tan δ/temperature curves were found. Shifts in T_g to a higher temperature for the elastomeric phase and to a lower temperature for the PMMA phase were observed. Therefore, the ENR/PMMA blends could be described as partly miscible blends. According to the thermogravimetry results, the decomposition temperatures of the blends increased as the levels of ENR and the epoxide molar percentage increased. The chemical interactions between the different phases of the blends could be the reason for the increase. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3561–3572, 2004     

A facile,green, versatile protocol to prepare polypropylene‐g‐poly(methyl methacrylate) copolymer by water‐solid phase suspension grafting polymerization using the surface of reactor granule technology polypropylene granules as reaction loci

A facile and environment friendly process, called water‐solid phase suspension grafting polymerization, was developed to prepare polypropylene‐g‐poly(methyl methacrylate) (PP‐g‐PMMA) copolymer with a submicrometer microdomain. In this approach, graft polymerization was elaborately regulated to occur within micropores of polypropylene particles prepared by reactor granule technology. FTIR spectra of the samples after extraction demonstrated that PMMA was successfully grafted onto the PP. The results showed grafting percentage (GP) of PMMA increased with the increasing monomer ratios to PP and that could reach 13.6%. Whereas the grafting efficiency decreased as the monomer ratio increased. The addition of second monomer styrene improved GP up to 24.5%. Differential Scanning Calorimetry tests showed that the grafting of PMMA have a slight effect on the melting point and the relative crystallinity of PP. TEM micrographs demonstrated PMMA domains distributed in PP matrix with sizes ranging from about 100 to 300 nm. In addition, Shear viscosity increased with the growing GP indicated by rheological measurement. The preliminary evaluation showed PP‐g‐PMMA was effective in improving the compatibility of PP/acrylonitrile‐styrene‐acrylate blends. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Physico‐mechanical properties of natural rubber sheets coated by polyethyleneimine‐functionalized poly(methyl methacrylate) nanoparticles

The surface modification of sulfur‐prevulcanized natural rubber (SPNR) sheets by the polyethyleneimine‐functionalized‐poly(methyl methacrylate) (PMMA/PEI) nanoparticles was successfully performed via a simple dipping method. The percentage of surface coverage (C_s) of the nanoparticles on SPNR sheets was found to be affected by a variation of nanoparticle latex concentrations and immersion times. The adsorption isotherm of PMMA/PEI nanoparticles on SPNR sheets was analyzed and found to fit well to the Freundlich model. After coating, it can be observed that the presence of PMMA/PEI nanoparticles on SPNR surface had no effects over the SPNR mechanical properties e.g., tensile strength, elongation at break, and hardness. On the other hand, the coated SPNR sheets showed a reduction of surface friction coefficients and interfacial adhesion up to 45 and 59%, respectively. Furthermore, PMMA/PEI nanoparticles adsorbed on the SPNR surface was subjected to stretching and wearing conditions, and found to be stable for at least seven stretching and wearing cycles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Natural rubber‐g‐methyl methacrylate/poly(methyl methacrylate) blends

The grafting of the methyl methacrylate (MMA) monomer onto natural rubber using potassium persulfate as an initiator was carried out by emulsion polymerization. The rubber macroradicals reacted with MMA to form graft copolymers. The morphology of grafted natural rubber (GNR) was determined by transmission electron microscopy and it was confirmed that the graft copolymerization was a surface‐controlled process. The effects of the initiator concentration, reaction temperature, monomer concentration, and reaction time on the monomer conversion and grafting efficiency were investigated. The grafting efficiency of the GNR was determined by a solvent‐extraction technique. The natural rubber‐g‐methyl methacrylate/poly(methyl methacrylate) (NR‐g‐MMA/PMMA) blends were prepared by a melt‐mixing system. The mechanical properties and the fracture behavior of GNR/PMMA blends were evaluated as a function of the graft copolymer composition and the blend ratio. The tensile strength, tear strength, and hardness increased with an increase in PMMA content. The tensile fracture surface examined by scanning electron microscopy disclosed that the graft copolymer acted as an interfacial agent and gave a good adhesion between the two phases of the compatibilized blend. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 428–439, 2001     

Nanostructured polymer blends based on polystyrene‐b‐polybutadiene‐b‐poly(methyl methacrylate) triblock copolymers modified with polystyrene and/or poly(methyl methacrylate) homopolymers

Morphologies of polymer blends based on polystyrene‐b‐ polybutadiene‐b ‐poly(methyl methacrylate) (SBM) triblock copolymer were predicted, adopting the phase diagram proposed by Stadler and co‐workers for neat SBM block copolymer, and were experimentally proved using atomic force microscopy. All investigated polymer blends based on SBM triblock copolymer modified with polystyrene (PS) and/or poly(methyl methacrylate) (PMMA) homopolymers showed the expected nanostructures. For polymer blends of symmetric SBM‐1 triblock copolymer with PS homopolymer, the cylinders in cylinders core?shell morphology and the perforated lamellae morphology were obtained. Moreover, modifying the same SBM‐1 triblock copolymer with both PS and PMMA homopolymers the cylinders at cylinders morphology was reached. The predictions for morphologies of blends based on asymmetric SBM‐2 triblock copolymer were also confirmed experimentally, visualizing a spheres over spheres structure. This work presents an easy way of using PS and/or PMMA homopolymers for preparing nanostructured polymer blends based on SBM triblock copolymers with desired morphologies, similar to those of neat SBM block copolymers. © 2017 Society of Chemical Industry     

Synthesis,characterization, and in vitro release of ibuprofen from poly(MMA‐HEMA) copolymeric core–shell hydrogel microspheres for biomedical applications

This article describes the development of a new crosslinked poly(methyl methacrylate‐2‐hydroxyethyl methacrylate) copolymeric core–shell hydrogel microsphere incorporated with ibuprofen for potential applications in bone implants. Initially poly(methyl methacrylate) (PMMA) core microspheres were prepared by free‐radical initiation technique. On these core microspheres, 2‐hydroxyethyl methacrylate (HEMA) was polymerized by swelling PMMA microspheres with the HEMA monomer by using ascorbic acid and ammonium persulfate. Crosslinking monomers such as ethylene glycol dimethacrylate (EGDMA) has also been included along with HEMA for polymerization. By this technique, it was possible to obtain core–shell‐type microspheres. The core is a hard PMMA microsphere having a hydrophilic poly(HEMA) shell coat on it. These microspheres are highly hydrophilic as compared to PMMA microspheres. The size of the hydrogel microspheres almost doubled when swollen in benzyl alcohol. These microspheres were characterized by various techniques such as optical microscopy, scanning electron microscopy, Fourier‐transformed infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The particle size of both microspheres was analyzed by using Malvern Master Sizer/E particle size analyzer. The in vitro release of ibuprofen from both microspheres showed near zero‐order patterns. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3045–3054, 2002; DOI 10.1002/app.10310     

Miscibility and crystallization kinetics of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/ poly(methyl methacrylate) blends

The miscibility and crystallization kinetics of the blends of random poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) [P(HB‐co‐HV)] copolymer and poly(methyl methacrylate) (PMMA) were investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). It was found that P(HB‐co‐HV)/PMMA blends were miscible in the melt. Thus the single glass‐transition temperature (T_g) of the blends within the whole composition range suggests that P(HB‐co‐HV) and PMMA were totally miscible for the miscible blends. The equilibrium melting point (T°_m) of P(HB‐co‐HV) in the P(HB‐co‐HV)/PMMA blends decreased with increasing PMMA. The T°_m depression supports the miscibility of the blends. With respect to the results of crystallization kinetics, it was found that both the spherulitic growth rate and the overall crystallization rate decreased with the addition of PMMA. The kinetics retardation was attributed to the decrease in P(HB‐co‐HV) molecular mobility and dilution of P(HB‐co‐HV) concentration resulting from the addition of PMMA, which has a higher T_g. According to secondary nucleation theory, the kinetics of spherulitic crystallization of P(HB‐co‐HV) in the blends was analyzed in the studied temperature range. The crystallizations of P(HB‐co‐HV) in P(HB‐co‐HV)/PMMA blends were assigned to n = 4, regime III growth process. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3595–3603, 2004