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We investigate for the first time the morphology and crystallization of two novel tetrablock quarterpolymers of polyethylene (PE), poly(ethylene oxide) (PEO), poly(ϵ-caprolactone) (PCL), and poly(l-lactide) (PLLA) with four potentially crystallizable blocks: PE187.1-b-PEO3715.1-b-PCL2610.4-b-PLLA197.6 (Q1) and PE299.5-b-PEO268.8-b-PCL237.6-b-PLLA227.3 (Q2) (superscripts give number average molecular weights in kg/mol, and subscripts give the composition in wt %). Their synthesis was performed by a combination of polyhomologation (C1 polymerization) and ring-opening polymerization techniques using a ″catalyst-switch″ strategy, either ″organocatalyst/metal catalyst switch″ (Q1 sample, 96% isotactic tetrads) or ″organocatalyst/organocatalyst switch″ (Q2 sample, 84% isotactic tetrads). Their corresponding precursors - triblock terpolymers PE-b-PEO-b-PCL, diblock copolymers PE-b-PEO, and PE homopolymers - were also studied. Cooling and heating rates from the melt at 20 °C/min were employed for most experiments: differential scanning calorimetry (DSC), polarized light optical microscopy (PLOM), in situ small-angle X-ray scattering/wide-angle X-ray scattering (SAXS/WAXS), and atomic force microscopy (AFM). The direct comparison of the results obtained with these different techniques allows the precise identification of the crystallization sequence of the blocks upon cooling from the melt. SAXS indicated that Q1 is melt miscible, while Q2 is weakly segregated in the melt but breaks out during crystallization. According to WAXS and DSC results, the blocks follow a sequence as they crystallize: PLLA first, then PE, then PCL, and finally PEO in the case of the Q1 quarterpolymer; in Q2, the PLLA block is not able to crystallize due to its low isotacticity. Although the temperatures at which the PEO and PCL blocks and the PE and PLLA blocks crystallize overlap, the analysis of the intensity changes measured by WAXS and PLOM experiments allows identifying each of the crystallization processes. The quarterpolymer Q1 remarkably self-assembles during crystallization into tetracrystalline banded spherulites, where four types of different lamellae coexist. Nanostructural features arising upon sequential crystallization are found to have a relevant impact on the mechanical properties. Nanoindentation measurements show that storage modulus and hardness of the Q1 quarterpolymer significantly deviate from those of the stiff PE and PLLA blocks, approaching typical values of compliant PEO and PCL. Results are mainly attributed to the low crystallinity of the PE and PLLA blocks. Moreover, the Q2 copolymer exhibits inferior mechanical properties than Q1, and this can be related to the PE block within Q1 that has thinner crystal lamellae according to its much lower melting point., This work has received funding from MINECO through projects MAT2017-83014-C2-1-P and MAT2017-88382-P, from the Basque Government through grant IT1309-19, and from the ALBA synchrotron facility through granted proposal u2020084441 (March 2020). We would like to thank the financial support provided by the BIODEST project; this project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 778092.

Transparent and flexible bionanocomposites with photochromic properties based on cellulose triacetate (CTA) and sol-gel synthesized V2O5 nanoparticles were prepared. Poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (EPE) triblock copolymer was added to achieve nanostructured materials and simultaneously control the dispersion of synthesized V2O5 nanoparticles. Investigated bionanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), atomic force microscopy (AFM), tensile tests, and UV–vis spectroscopy. FTIR results confirmed the presence of hydrogen bonds in the bionanocomposites. The miscibility between components improved with the increase of sol-gel content resulting in a decrease of the Tg and Tm of CTA phase as indicated by DSC results. Addition of EPE triblock copolymer enhanced the photochromic properties of bionanocomposites reducing the time of recovery to the initial state after 5 min of UV light irradiation. The biocompatibility of pure CTA and EPE/CTA blends as well as the photochromic properties provided by synthesized V2O5 nanoparticles make their transparent and flexible bionanocomposites ideal for possible future applications.

An efficient method to improve the mechanical performance of a commercially available photocure resin is described wherein the resin is modified with a mixture of a cycloaliphatic epoxy and an anhydride curing agent. Photocured samples are thermally treated in a subsequent step to cure the epoxy to obtain an interpenetrated polymer network (IPN) and also complete reaction of the acrylate monomers remaining from the photocure. The latter is accomplished by a thermal radical initiator added earlier into the formulation together with the epoxy-anhydride. The thermal properties and microstructure of the resulting IPN are analyzed. Uniform and quantitative conversions are obtained, with glass transition temperatures comparable to conventional epoxies. The liquid, uncured samples containing different amounts of epoxy are stable at 30 °C for several weeks. In the fully cured epoxy-rich materials, nano-scale phase separation is observed by atomic force microscopy. This is corroborated by the existence of multiple relaxations determined by dynamic mechanical analysis analysis. Specimens from a formulation containing 50% by weight of epoxy-anhydride are 3D printed in a customized masked image processing stereolithography, thermally treated, and are subjected to compression tests. Results show that Young's modulus increases by 900% over the neat resin

Stereolithography (SL) stands out as a relatively fast additive manufacturing method to produce thermoset components with high resolutions. The majority of SL resins consist of acrylate monomers which result in materials with curing-induced shrinkage problems and this, in addition to the incomplete and non-uniform conversions reached in the SL process, results in poor mechanical properties. To address this issue, a dual-curing formulation was developed by mixing an epoxy monomer into a commercial multi-acrylate SL resin: the first curing stage is acrylate free-radical photopolymerization at ambient temperature, and the second curing stage is cationic epoxy homopolymerization at higher temperatures. The fully dual-cured materials are macroscopically homogeneous, with nanoscale domains observed by Atomic Force Microscopy (AFM), and with unimodal tan delta peaks observed in Dynamic Mechanical Analysis (DMA). The uncured material was storage stable at ambient conditions for at least 9 weeks since the epoxy part was virtually unreactive at these temperatures. With the dual-cured materials, a nearly 10-fold increase in Young’s modulus was achieved over the neat acrylate resin. At the thermal curing stage, the presence of diperoxyketal thermal radical initiator to the liquid formulation facilitated the polymerization of unreacted acrylates that remained from the SL process simultaneously with epoxy homopolymerization and helped the material attain improved properties.

Waterborne poly(urethane-urea)s (WPUUs) can be employed as a base for the preparation of new materials with novel properties and applications, such as hydrogels. In this work, sodium alginate (SA) was incorporated into WPUUs and their nanocomposites with TiO2 nanoparticles. The influence of the addition of SA and TiO2 nanoparticles on the final properties of WPUUs based hydrogels was investigated. It was proven that the hydrogen bonding interactions that took place between WPUU and SA strongly affected the final properties. The glass transition temperature and thermal stability of investigated hydrogels were affected depending on the soft segment composition. The prepared hydrogels exhibited swelling ability in an acidic medium. The porous structure of the prepared hydrogels was confirmed by the scanning electron microscope (SEM) measurements. In fact, the mechanical properties indicated an improvement in the compressive modulus with the increase of the SA content. Furthermore, the prepared hydrogels allowed the cell proliferation of human fibroblasts.

Achieving adhesion to materials with a low surface energy is a challenge when designing new soft adhesives.With this question in mind, waterborne poly(urethane-urea) (WPUU) dispersions based on poly(ethylene oxide)(PEO) homopolymer and poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (PEO-b-PPO-b-PEO) and poly(propylene oxide-b-ethylene oxide-b-propylene oxide) (PPO-b-PEO-b-PPO) triblock copolymers were prepared. Adhesives cast from the dispersions exhibited better adhesion on a low surface energy polypropylene (PP) probe than on a high surface energy steel probe. Moreover, with the aim of improving the adhesive performance of the WPUUs for pressure sensitive adhesive (PSA) applications, bilayer systems were designed. They were prepared using two WPUUs with differing viscoelastic behavior (one more solid-like and the other one, more liquid-like)to create a gradient in the viscoelastic properties. This strategy led to adhesive materials that exhibited fibrillation during probe tack measurements using a steel probe, which is typical of PSAs. Finally, prototype adhesive tapes were prepared from one of the bilayer systems. These adhesive tapes performed in a peel test in a similar way as a domestic commercial adhesive tape, making them interesting for that potential application.

This work presents an in-depth study of fiber-induced nucleation and crystalline morphology in polybutene-1/single-fiber composites. The nucleation ability of various fibers, including carbon, glas...

The structure, morphology and final properties of synthesized waterborne poly(urethane-urea)s (WPUU) based on triblock copolymers containing hydrophilic poly(ethylene oxide) PEO block as polyol has been studied. Different molecular weight poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (PEO-b-PPO-b-PEO) and poly(propylene oxide-b-ethylene oxide-b-propylene oxide) (PPO-b-PEO-b-PPO) triblock copolymers were used as polyols acting as soft segment. A Volatile Organic Compounds (VOCs) free synthesis procedure was followed to synthesize WPUU dispersions. Particle size, solid content and viscosity of the WPUU dispersions were measured. Atomic force microscopy was used to study the morphology, whereas size exclusion chromatography helped determining molecular weight of the WPUU films, prepared by solvent casting. Chemical structure was determined by FTIR and 1H NMR. Moreover, transmittance and thermal and mechanical properties of the WPUU films were also investigated. The use of PEO-b-PPO-b-PEO triblock copolymer led to dispersions with higher molecular weights and viscosities. WPUU films based on this triblock copolymer showed better mechanical properties, nevertheless they exhibited a lower transparency. All triblock copolymer based WPUU films led to nanostructured materials, which can act as template for dispersion of different kind of fillers extending possible application of waterborne polyurethanes. This work spotlights the possibility to synthesize waterborne poly(urethane-urea) dispersions with tailored properties using triblock copolymers as polyols.

Reactive extrusion is a cost-effective and environmentally-friendly method to produce new materials with enhanced performance properties. At present, reactive extrusion allows in-situ polymerization, modification/functionalization of polymers or chemical bonding of two (or more) immiscible phases, which can be carried out on commonly used extrusion lines. Although reactive extrusion has been known for many years, its application for processing of bio-based polymer blends and composites is a relatively new direction of scientific research. This work presents a literature review on recent advances in the processing of bio-based polymer blends and composites via reactive extrusion. We described compatibilization mechanisms for different types of biodegradable polymeric materials based on: (i) aliphatic polyesters, (ii) aliphatic polyesters/starch and (iii) aliphatic polyester/natural rubber systems. A special attention was focused on conventional and dynamic cross-linking of bio-based polymer blends and composites as an effective way to prepare new materials with unique properties e.g. biodegradable thermoplastic elastomers or shape-memory materials. Advantages and limitations affecting future trends in development of biodegradable polymer blends and composites reactive extrusion are also discussed.

Made available in DSpace on 2018-11-26T17:42:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) In this work, for the first time bacterial cellulose (BC) hydrogel membranes were used for the fabrication of antimicrobial cellulosic nanocomposites by hydrothermal deposition of Cu derivative nanoparticles (i.e. Cu(0) and CuxOy species). BC-Cu nanocomposites were characterized by FTIR, SEM, AFM, XRD and TGA, to study the effect of hydrothermal processing time on the final physicochemical properties of final products. XRD result show that depending on heating time (3-48 h), different CuxOy phases were achieved. SEM and AFM analyses unveil the presence of the Cu(0) and copper CuxOy nanoparticles over BC fibrils while the surface of 3D network became more compact and smother for longer heating times. Furthermore, the increase of heating time placed deleterious effect on the structure of BC network leading to decrease of BC crystallinity as well as of the on-set degradation temperature. Notwithstanding, BC-Cu nanocomposites showed excellent antimicrobial activity against E. coli, S. aureus and Salmonella bacteria suggesting potential applications as bactericidal films. Univ Fed Piaui, Dept Quim, Campus Minist Petronio Portela, BR-64049550 Teresina, PI, Brazil Univ Estadual Paulista, Inst Quim Araraquara, Dept Quim Geral & Inorgan, Rua Prof Francisco Degni,55, BR-14800060 Araraquara, SP, Brazil Centro Univ Araraquara, Lab Biopolimeros & Biomat BIOPOLMAT, Rua Carlos Gomes,1217, BR-14801320 Araraquara, SP, Brazil Univ Basque Country UPV EHU, Dpto Ingn Quim & Medio Ambiente, Escuela Politecn Donostia San Sebastian, Pza Europa 1, Donostia San Sebastian 20018, Spain Univ Luterana Brasil, Programa Posgrad Genet & Toxicol Aplicada, Ave Farroupilha,8001,Predio 01, BR-92450900 Canoas, RS, Brazil Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP, Brazil Univ Estadual Paulista, Inst Quim Araraquara, Dept Quim Geral & Inorgan, Rua Prof Francisco Degni,55, BR-14800060 Araraquara, SP, Brazil FAPESP: 2015/ 09833-0 FAPESP: 2016/06612-6

Triple crystalline triblock terpolymers are materials with remarkable semicrystalline superstructures. In this work, we report for first time the alternating triple lamellar morphology that self-assembles inside spherulites of a triblock terpolymer composed of poly(ethylene oxide) (PEO), poly(e-caprolactone) (PCL), and poly(l-lactide) (PLLA). The morphology of the PEO-b-PCL-b-PLLA triblock terpolymer is compared to an analogous PCL-b-PLLA diblock copolymer. Both diblock and triblock form a single phase in the melt. Two crystallization protocols were employed to create particular crystalline morphologies. In both cases, the isothermal crystallization of the PLA block is induced first (at 81 °C, a temperature above the melting points of both PCL and PEO blocks) and PLLA spherulites form a template, whereupon cooling the other two blocks can crystallize within the PLLA interlamellar spaces. WAXS analysis demonstrated the double crystalline and triple crystalline nature of the materials. The lamellar structur...

Two different, molecular weight and blocks ratio, poly(ethylene-b-ethylene oxide) block copolymers (PE-b-PEO) were used as nanostructuration agent for epoxy based thermosets and as surfactant for sol-gel synthesized titanium dioxide (TiO2) nanoparticles. Obtained DSC results confirmed the miscibility of PEO block of PE-b-PEO block copolymer with epoxy monomer in PE-b-PEO/DGEBA unreactive mixtures and with DGEBA/MCDEA matrix in cured systems modified with PE-b-PEO block copolymer without or with TiO2 nanoparticles. The dilution effect caused by the addition of PE-b-PEO block copolymer on the epoxy/amine reaction mixture was verified. AFM phase images proved that nanostructured thermosetting systems can be reached in function of PE-b-PEO block copolymer content. Good dispersion and, in the case of the cured systems modified with higher molecular weight and higher PEO content PE-b-PEO block copolymer, selective localization of TiO2 nanoparticles can be achieved. The morphology of investigated thermosetting systems and the good dispersion of TiO2 nanoparticles depend on the PEO block content in PE-b-PEO block copolymer and its molecular weight. Transparent PE-b-PEO block copolymer nanostructured thermosetting systems with hydrophilic character and well dispersed or positioned TiO2 nanoparticles can be obtained.

Centre of Polymer and Carbon Materials, Polish Academy of Sciences, University of Wolverhampton, University of the Basque Country (UPV/EHU), Gdynia Maritime University

In many areas of application of conventional non-degradable cross-linked polyurethanes (PUR), there is a need for their degradation under the influence of specific environmental factors. It is practiced by incorporation of sensitive to degradation compounds (usually of natural origin) into the polyurethane structure, or by mixing them with polyurethanes. Cross-linked polyurethanes (with 10 and 30%wt amount of synthetic poly([R,S]-3-hydroxybutyrate) (R,S-PHB) in soft segments) and their physical blends with poly([d,l]-lactide) (PDLLA) were investigated and then degraded under hydrolytic (phosphate buffer solution) and oxidative (CoCl2/H2O2) conditions. The rate of degradation was monitored by changes of samples mass, morphology of surface and their thermal properties. Despite the small weight losses of samples, the changes of thermal properties of polymers and topography of their surface indicated that they were susceptible to gradual degradation under oxidative and hydrolytic conditions. Blends of PDLLA and polyurethane with 30 wt% of R,S-PHB in soft segments and PUR/PDLLA blends absorbed more water and degraded faster than polyurethane with low amount of R,S-PHB.

Optical properties of novel polymer dispersed liquid crystal (PDLC) blends based on two different low molecular weight nematic liquid crystals, 4′-(hexyloxy)-4-biphenylcarbonitrile (HOBC) and N-(4-ethoxybenzylidene)-4-butylaniline (EBBA), and poly(ethylene-b-ethylene oxide) block copolymer (PE-b-PEO), were studied to develop optically reversible PDLC blends applying a temperature gradient. Differential scanning calorimetry (DSC) showed that the liquid crystals, HOBC and EBBA, maintain their nematic-isotropic transition in designed PDLC blends, which was visualized by optical microscopy (OM). Results obtained using photoluminescence and UV–vis spectroscopies indicated that HOBC and EBBA liquid crystals maintain their reversible optical behavior passing from opaque to transparent state when temperature gradient was applied. The reversible switching process was proved in four consecutive heating/cooling cycles. Designed thermo-responsive PDLC blends possessed interesting optical properties, which make them potential candidates to be use as temperature sensors or thermo-optical devices.

Conductive polyurethane foam nanocomposites were prepared by the incorporation of graphene flakes. Graphene flakes were obtained from graphite by the top-down method of liquid exfoliation in N–methyl pyrrolidone and size-selected by centrifugation. A deep characterization of graphene flakes was performed for a better understanding of their role as nanoentities in polyurethane foam matrix. Thus, morphology, with special emphasis in the number of layers, was analyzed by Raman spectroscopy, atomic force microscopy and transmission electron microscopy. Electrostatic force microscopy was used to verify the conductive nature of graphene flakes. This technique showed to be effective for the assessment of both morphology and conductive properties of graphene flakes. Regarding the electrical behavior of the nanocomposite foams, it was determined that the electrical resistance depended on both the graphene content and the compressive deformation applied to the material.

Surface morphology development for SBM triblock copolymer thin films has been studied by atomic force microscopy. The effect of copolymer composition and solvent on the final morphology has been investigated. Obtained results indicated that depending on the block ratio (symmetric or asymmetric with minority middle block) and solvent, lamellar, hexagonal, cylindrical, or spheres in lamellae (ls)-type morphologies can be achieved at film surfaces. The influence of the interaction parameters among blocks and solvents and cohesive energy values of block pairs on the final morphology has been proved. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers

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 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 expected nanostructures. For polymer blends of symmetric SBM-1 triblock copolymer with PS homopolymer, cylinders in cylinders core-shell morphology and perforated lamellae morphology were obtained. Moreover, modifying the same SBM-1 triblock copolymer with both PS and PMMA homopolymers 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 presented 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.

Made available in DSpace on 2018-12-11T17:23:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-11-05 A strain isolated from Kombucha tea was isolated and used as an alternative bacterium for the biosynthesis of bacterial cellulose (BC). In this study, BC generated by this novel bacterium was compared to Gluconacetobacter xylinus biosynthesized BC. Kinetic studies reveal that Komagataeibacter rhaeticus was a viable bacterium to produce BC according to yield, thickness and water holding capacity data. Physicochemical properties of BC membranes were investigated by UV–vis and Fourier transform infrared spectroscopies (FTIR), thermogravimetrical analysis (TGA) and X-ray diffraction (XRD). Additionally, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were also used for morphological characterization. Mechanical properties at nano and macroscale were studied employing PeakForce quantitative nanomechanical property mapping (QNM) and dynamic mechanical analyzer (DMA), respectively. Results confirmed that BC membrane biosynthesized by Komagataeibacter rhaeticus had similar physicochemical, morphological and mechanical properties than BC membrane produced by Gluconacetobacter xylinus and can be widely used for the same applications. Laboratório de Biopolimeros e Biomateriais (BIOPOLMAT) Centro Universitário de Araraquara, Araraquara Group ‘Materials + Technologieś (GMT) Department of Chemical and Environmental Engineering Engineering College of Gipuzkoa University of the Basque Country (UPV/EHU), Plaza Europa 1 Laboratório de Pesquisa Desenvolvimento & Inovação Apis Flora Ind. Coml. Ltda, Ribeirão Preto Institute of Chemistry-São Paulo StateUniversity-UNESP Institute of Chemistry-São Paulo StateUniversity-UNESP

Bacterial cellulose (BC) produced by some bacteria, among them Gluconacetobacter xylinum, which secrets an abundant 3D networks fibrils, represents an interesting emerging biocompatible nanomaterial. Since its discovery BC has shown tremendous potential in a wide range of biomedical applications, such as artificial skin, artificial blood vessels and microvessels, wound dressing, among others. BC can be easily manipulated to improve its properties and/or functionalities resulting in several BC based nanocomposites. As example BC/collagen, BC/gelatin, BC/Fibroin, BC/Chitosan, etc. Thus, the aim of this review is to discuss about the applicability in biomedicine by demonstrating a variety of forms of this biopolymer highlighting in detail some qualities of bacterial cellulose. Therefore, various biomedical applications ranging from implants and scaffolds, carriers for drug delivery, wound-dressing materials, etc. that were reported until date will be presented.

Made available in DSpace on 2018-12-11T17:27:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-06-05 Three different low molecular weight nematic liquid crystals (LCs) were used to impregnate bacterial cellulose (BC) film. This simple fabrication pathway allows to obtain highly transparent BC based films. The coating of BC film with different liquid crystals changed transmittance spectra in ultraviolet-visible region and allows to design UVC and UVB shielding materials. Atomic force microscopy results confirmed that liquid crystals coated BC films maintain highly interconnected three-dimensional network characteristic of BC film and simultaneously, transversal cross-section scanning electron microscopy images indicated penetration of liquid crystals through the three-dimensional network of BC nanofibers. Investigated BC films maintain nematic liquid crystal properties being switchable photoluminiscence as a function of temperature during repeatable heating/cooling cycles. Conductive response of the liquid crystal coated BC films was proved by tunneling atomic force microscopy measurement. Moreover, liquid crystal coated BC films maintain thermal stability and mechanical properties of the BC film. Designed thermoresponsive materials possessed interesting optical and conductive properties opening a novel simple pathway of fabrication liquid crystal coated BC films with tuneable properties. Group 'Materials + Technologies' (GMT) Department of Chemical and Environmental Engineering Polytechnic School University of the Basque Country (UPV/EHU), Plaza Europa 1 Laboratory of Photonic Materials Institute of Chemistry São Paulo State University - UNESP Laboratório de Química Medicinal e Medicina Regenerativa (QUIMMERA) Centro Universitário de Araraquara Laboratory of Photonic Materials Institute of Chemistry São Paulo State University - UNESP

Different block copolymer dispersed liquid crystals blends based on poly(ethylene-b-ethylene oxide) (PE-b-PEO) and modified with low molecular weight nematic liquid crystals, 4′-(hexyloxy)-4-biphenylcarbonitrile (HOBC) and N-(4-ethoxybenzylidene)-4-butylaniline (EBBA) were prepared and characterized. The miscibility between each block of PE-b-PEO block copolymer and nematic liquid crystals was studied using differential scanning calorimetry (DSC). DSC results were in good agreement with the miscibility prediction supported by the solubility parameters and miscibility effect in polymer dispersed liquid crystals blends based on polyethylene oxide (PEO) homopolymer. Thermal stability of PE-b-PEO/HOBC and PE-b-PEO/EBBA blends was also studied. Block copolymer dispersed liquid crystals blends maintained the nematic/isotropic transition in function of the ratio between PE-b-PEO block copolymer and nematic liquid crystals indicating the potential application of the designed materials.

Two different methods were employed for the preparation of cellulose triacetate (CTA) based nanocomposites without and with poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (EPE) triblock copolymer and modified with sol-gel synthesised titanium dioxide nanoparticles (TiO2). The hybrid nanocomposites were prepared by solvent casting (SC) and solvent vapour annealing (SVA) methods. The hybrid nanocomposite films obtained by SVA presented smoother surfaces, and consequently, higher gloss values. As for transparency, only the hybrid nanocomposites prepared by SVA remained completely transparent even with high sol-gel content due to the nanostructuration of EPE triblock copolymer. Furthermore, the UV-shielding properties provided by the TiO2 nanoparticles were not modified regardless of the employed preparation method. Finally, the nanocomposites prepared by SVA presented a higher Young's modulus and tensile strength than the SC nanocomposites. The obtained results proved the efficiency of the SVA method to control the relationship between the morphology and the final properties of the hybrid nanocomposite films leading to materials with enhanced surface, optical, and mechanical properties.

Biodegradable films for food packaging have received increasing attention from the industry in recent years. Due to its extraordinary properties, chitosan has demonstrated to be an exceptional candidate for that kind of applications. In this study, chitosan-based films modified with an azopolymer and silver nanoparticles were prepared by solvent-casting. The quality and homogeneity of the samples was satisfactory and films with thicknesses of the order of 25 µm and of various sizes, with diameters ranging from 5 to 15 cm, were obtained. The developed hybrid films were characterized by several experimental techniques including: atomic force microscopy, attenuated total reflectance-Fourier transformed infrared spectroscopy, thermogravimetric analysis, ultraviolet–visible spectroscopy and water contact angle measurements. In addition, the mechanical properties of the samples were investigated. Specifically, the tensile strength and the elastic modulus were enhanced in the films modified with azopolymer and silver nanoparticles. Moreover, the developed films showed reversible induced birefringence properties, indicating that they could be used for optical storage applications.

In this work, the effect of the addition of different amount of nanosized hydroxyapatite (nHA) on the shape memory behavior of blends based on poly (lactic acid) (PLA) and poly (ε-caprolactone) (PCL) has been studied. In particular PLA/PCL blend with 70 wt % PLA has been reinforced with 0.5, 1 and 3 wt % nHA. Moreover, the relationship between the morphology and the final properties of the nanocomposites has been investigated by field emission scanning electron microscopy, confocal Raman spectroscopy and atomic force microscopy. In particular, PeakForce has been used to study quantitative nanomechanical properties of the multifunctional materials leading to conclusion that nHA increase the phase separation between PLA and PCL as well as act as reinforcements for the PCL-rich phase of the nanocomposites. Furthermore, excellent thermally-activated shape memory response has been obtained for all the nanocomposites at 55 °C. Finally, the disintegration under composting conditions at laboratory scale level was studied in order to confirm the biodegradable character of these nanocomposites. Indeed, these materials are able to be used for biomedical issues as well as for packaging applications where both thermally-activated shape memory effect and biodegradability are requested., Authors thank the Spanish Ministry of Economy, Industry and Competitiveness, MINEICO, (MAT2017-88123-P) and the Regional Government of Madrid (S2013/MIT-2862) for the economic support. M.P.A. and L.P. acknowledge the “Juan de la Cierva” (FJCI-2014- 20630) and “Ramon y Cajal” (RYC-2014-15595) contracts from the MINEICO, respectively. The authors also thanks CSIC for the I-Link project (I-Link1149)

Made available in DSpace on 2018-12-11T17:15:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01 Bacterial cellulose/carboxymethylcelullose (BC/CMC) biocomposites with different DS-CMC (DS from 0.7 to 1.2) were developed in order to evaluate their impact as a drug delivery system. Biocomposites were loaded with methotrexate (MTX) as an alternative for the topical treatment of psoriasis. Scanning electron microscopy and atomic force microscopy showed that the CMC coated the cellulose nanofibers, leading to the decrease of the elastic modulus as the DS of CMC increased. BC/CMC0.9 exhibited the lower liquid uptake (up to 11 times lower), suggesting that the more linear structure of the intermediate substitute CMC grade (0.9) was able to interact more strongly with BC, resulting in a denser structure. All samples showed a typical burst release effect in the first 15 min of test, however the BC/CMC0.9 biocomposite promoted a slight lowering of MTX release rates, suggesting that the DS of CMC can be considered the key factor to modulate the BC properties. University of Araraquara – U NIARA Institute of Chemistry São Paulo State University – UNESP Interdisciplinary Laboratory of Advanced Materials Centro de Ciências da Natureza- CNN Federal University of Piaui – UFPI Group ‘Materials + Technologies’ (GMT) Department of Chemical and Environmental Engineering Engineering College of Gipuzkoa University of the Basque Country (UPV/EHU) Department of Drugs and Pharmaceuticals School of Pharmaceutical Sciences SãoPaulo State University – UNESP Institute of Chemistry São Paulo State University – UNESP Department of Drugs and Pharmaceuticals School of Pharmaceutical Sciences SãoPaulo State University – UNESP

Made available in DSpace on 2018-12-11T16:46:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-06-01 Eusko Jaurlaritza In this study fabrication and characterization of transparent nanostructured composite films based on cellulose triacetate (CTA) and poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (EPE) triblock copolymer were presented. The effect of the addition of EPE triblock copolymer on the thermal stability, morphology, and mechanical properties of cellulose triacetate films was investigated. The triblock EPE was chosen since PEO blocks interact favorably with CTA, whereas, PPO blocks remain immiscible which provokes a microphase separation. This allows to obtain EPE/CTA composite films with ordered microphase-separated structures where PPO spherical microdomains are well-dispersed in PEO/CTA matrix by simple solvent-evaporation process. During this process, PEO block chains selectively interact with CTA by strong interpolymer hydrogen-bonding while PPO block microseparated. The addition even 40 wt% of EPE leads to nanostructured EPE/CTA composite. The cytotoxicity assay of CTA and EPE/CTA composite films confirm non-toxic character of designed transparent nanostructured composites based on sustainable matrices. ‘Materials + Technologies’ Group (GMT) Department of Chemical and Environmental Engineering Faculty of Engineering University of the Basque Country (UPV/EHU), Plaza Europa 1 Faculty of Engineering Vitoria-Gasteiz University of the Basque Country (UPV/EHU), C/Nieves Cano Laboratory of Photonic Materials Institute of Chemistry Sao Paulo State University (UNESP) Medicinal Chemistry and Regenerative Medicine (QUIMMERA) University Center of Araraquara (UNIARA) Laboratory of Photonic Materials Institute of Chemistry Sao Paulo State University (UNESP)

Thermosetting systems based on DGEBA epoxy resin and poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (EPE) triblock copolymer were prepared and investigated. Different mixtures were obtained by using different contents of EPE block copolymer in order to study the influence of the modifier on the properties of the final materials. All thermosetting systems were prepared without using any solvent and were cured at ambient temperature, taking into account the lower critical solution temperature (LCST) behavior of the block copolymer. DSC results indicated that the addition of block copolymer affected to the curing reaction time and to the glass transition temperature of the mixtures and also the miscibility of EPE triblock copolymer in the epoxy resin was proved. The morphologies studied by AFM and TEM showed clear nanostructuration up to 25 wt % EPE content. The addition of 5 and 15 wt % of EPE block copolymer led to a considerable improvement in the toughness of the materials. When EPE block copolymer was added to the epoxy resin, the surface became more hydrophilic and the UV–vis transmittance decreased slightly maintaining a high level of transparency.

The aim of this contribution was the study of the influence of polymer matrix on the photo-induced orientation of azobenzene groups. Notably, an azo-prepolymer bearing hydroxyl groups was selectively confined in self-assembled phases of different block copolymers, randomly-epoxidized polystyrene-b-polybutadiene-b-polystyrene (SBSep) and polystyrene-b-poly-4-vinylpyridine (S4VP). The formation of hydrogen bonds between the azo-prepolymer and poly-4-vinylpyridine block, as well as the effect of the local environment surrounding the azo-prepolymer were investigated by Fourier transform infrared and ultraviolet–visible spectroscopies. In addition, the reversible optical storage properties of the developed materials were also studied. Birefringent properties of the systems based on S4VP were strongly enhanced by intermolecular interactions with the azo-prepolymer. Specifically, the maximum birefringence level attained by a system containing 13 wt% of azobenzene was around 2.3 × 10−2 and its remaining birefringence was nearly three times higher than that of the neat azo-prepolymer. Furthermore, a morphological analysis of the designed materials was carried out by atomic force microscopy. Taking into account that the control of the microdomains ordering in block copolymer films is of current interest, special attention was focused on the influence of different variables on the arrangement of the block copolymer microdomains.

Many efforts in the field of azobenzene-containing polymers are concentrated on exploring new material concepts to obtain efficient and stable photo-induced anisotropy. Here, an easy approach to improve the birefringent properties of an epoxy-based azo-prepolymer is reported. The designed azo-prepolymer was selectively confined in a self-assembled domain of a block copolymer and thanks to the formation of hydrogen bonds a major enhancement of its optical response was achieved. In particular, the resulting material presented double the maximum level of optical anisotropy of the neat azo-prepolymer and nearly 80% of remaining birefringence.

We report an approach for the design of nanostructured thermoplastic elastomeric materials consisting of poly(styrene-b-butadiene-b-styrene) and epoxy. This approach consists in the epoxidation of PB block and further mixing with low contents of the DGEBA:MCDEA system. Morphological behavior as well as thermal and mechanical properties have been investigated. The modification of epoxidized SBS with 10, 20, and 30 wt % epoxy system induces microphase separation at nanoscale from a poorly to well-ordered self-assembled morphology where the shape of these structures depends greatly on the mixture compositions, showing a transition from worm-like to lamellae. The generated nanostructures are accessible owing to the miscibility between the epoxidized PB block and the epoxy system that have been confirmed by an increment on the Tg (before and after curing) of this block in the mixture. The mixing produces a significant increase on strength and stiffness being more relevant in the system with 30 wt % epoxy and w...

Summary: Inorganic-organic nanostructured thermosetting composites based on poly(styrene-block-ethylene oxide) (SEO) block copolymer used as templating agent and titanium dioxide (TiO2) nanoparticles synthesized via sol-gel were prepared. The morphologies generated in the binary and ternary epoxy-based systems were studied using atomic force microscopy (AFM). Ternary systems showed good dispersion of synthesized nanoparticles and simultaneously maintained nanostructure order of the cured block copolymer/epoxy-based system due to self-assembly of SEO block copolymer. Transparent multifunctional advanced thermosetting materials with tuneable properties controlled varying the ratio between inorganic and organic components was successfully designed.

Summary: Self-assembly is an interesting strategy for the creation of periodic structures at the nanoscale. The microphase separation in a linear ternary block copolymer consisting on three immiscible components (ABC), give rise to the formation of different final morphologies that can be controlled by various parameters. In this work, the morphologies of three poly(styrene-b-butadien-b-methyl methacrylate) triblock copolymers with similar molecular weight and their blends with PS homopolymers were studied by atomic force microscopy (AFM). Redistribution of the homopolymer in blends generates new structures could be tailored according to the desired applications.

Made available in DSpace on 2018-12-11T17:23:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-07-15 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The preparation of composite materials has gained tremendous attention due to the potential synergy of the combined materials. Here we fabricate novel thermal/electrical responsive photonic composite films combining cellulose nanocrystals (CNC) with a low molecular weight nematic liquid crystal (NLC), 4′-(hexyloxy)-4-biphenylcarbonitrile (HOBC). The obtained composite material combines both intense structural coloration of photonic cellulose and thermal and conductive properties of NLC. Scanning electron microscopy (SEM) results confirmed that liquid crystals coated CNC films maintain chiral nematic structure characteristic of CNC film and simultaneously, transversal cross-section scanning electron microscopy images indicated penetration of liquid crystals through the CNC layers. Investigated composite film maintain NLC optical properties being switchable as a function of temperature during heating/cooling cycles. The relationship between the morphology and thermoresponsive in the micro/nanostructured materials was investigated by using transmission optical microscopy (TOM). Conductive response of the composite films was proved by Electrostatic force microscopy (EFM) measurement. Designed thermo- and electro-responsive materials open novel simple pathway of fabrication of CNC-based materials with tunable properties. São Paulo State University (Unesp) Institute of Chemistry, CP 355 Group ‘Materials + Technologies’ (GMT) Department of Chemical and Environmental Engineering Engineering College of Gipuzkoa University of the Basque Country (UPV/EHU), Plaza Europa 1 Laboratório de Biopolímeros e biomateriais (BioPolMat) Universidade de Araraquara São Paulo State University (Unesp) Institute of Chemistry, CP 355

Miscibility, crystallization and morphology of unsaturated polyester (UP) matrices, nanostructured with a poly[(ethylene oxide)- b -(propylene oxide)- b -(ethylene oxide)] (PEO- b -PPO- b -PEO) block copolymer (BCP) from 0 to 50 wt% has been investigated. Additionally, the role of each block on miscibility and morphology of cured mixtures was studied. Behaviours of non-reactive mixtures of UP thermosetting precursor with two BCPs composed of similar and strong immiscible central PPO block were compared. It was found that one BCP had PEO blocks with not enough molecular weight to compatibilize the PPO block with the UP thermosetting precursor at room temperature. Transmitted light intensity study of mixtures indicated that during curing at 35 °C no macrophase separation took place, contrary to the systems cured at temperatures equal or higher than 60 °C. Curing mixtures at 35 °C produced nanostructured matrices with almost unchanged transparency. Phase separation and miscibility of BCP with UP matrix were measured by means of DSC and DMA. AFM analysis showed worm-like morphology with diameters from 10 to 20 nm and length that evolved from 50 nm to 1 μm with increase of BCP content.

Microphase separated epoxy-based materials modified with an amphiphilic poly(styrene-block-ethylene oxide) diblock copolymer (PS-b-PEO) with low amount of PEO-block as well as ternary systems modified with this block copolymer and containing via sol–gel in situ synthesized TiO2 nanoparticles were prepared and characterized. The obtained results indicate that block copolymer had enough amount of PEO-block in order to achieve microphase separated materials for a high range of PS-b-PEO contents, morphologies changing from spherical micelles to long wormlike micelles passing through vesicles upon increasing copolymer amounts. In the case of 20 wt.% inorganic/organic epoxy-based materials, addition of synthesized TiO2 nanoparticles into PS-b-PEO-(DGEBA/MCDEA) system led to location of the nanoparticles in PEO-block/epoxy-rich confined between two microphase separated PS-block-rich phases. Designed highly transparent multiphase inorganic/organic epoxy-based materials possess interesting specific properties such as high UV shielding efficiency and high water repellence.

Azo-containing polymers are of particular interest in the design of materials for applications in optical recording. The aim of this contribution was the synthesis and characterization of optically active epoxy-based nanostructured thermosets obtained using epoxidized poly(styrene-b-butadiene-b-styrene) (SBS) as templating agent and modified with azobenzene groups. Morphological analysis by means of atomic force microscopy, as well as an investigation about the anisotropic optical properties of the developed materials was carried out. Different types of morphologies from micelles without long-range order to nanostructures with long-range order were achieved depending on the content of epoxidized block copolymer and azobenzene, and on the extent of epoxidation of butadiene blocks. In addition, the study of optical anisotropy showed a clear dependence of the optical storage properties upon the concentration of azo-chromophore in the samples. In particular, a thermoset containing 12.3 wt % of azo-dye and 5 p...

Novel inorganic/organic epoxy based materials were fabricated using both poly(styrene-b-ethylene oxide) (SEO) block copolymer and synthesized TiO2 nanoparticles as modifier. The influence of the ratio between modifiers on the final morphology generated in the investigated epoxy systems was studied by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Results indicated that even for high nanoparticle content, TiO2 nanoparticles synthesized via sol-gel were homogenously dispersed in the epoxy-rich phase. The morphology of the inorganic/organic epoxy based composites consisted of both well-dispersed TiO2 nanoparticles and microphase separated PS block in the continuous PEO block/epoxy-rich phase since block copolymer acted as templating agent for selective location of TiO2 nanoparticles. Differential scanning calorimetry (DSC) was used to study the curing behavior and the influence of the type and quantity of modifier on the glass transition temperature of epoxy matrix. Additionally, optical properties, transparency and UV-shielding efficiency of these new multiphase advanced thermosetting materials were also investigated.

A comparative study on the self-assembled nanostructured morphology and the rheological and mechanical prop- erties of four different triblock copolymers, based on poly(styrene-block-butadiene-block-styrene) and poly(styrene-block- isoprene-block-styrene) matrices, and of their respective nanocomposites with 1 wt% silver nanoparticles, is reported in this work. In order to obtain well-dispersed nanoparticles in the block copolymer matrix, dodecanethiol was used as surfac- tant, showing good affinity with both nanoparticles and the polystyrene phase of the matrices as predicted by the solubility parameters calculated based on Hoftyzer and Van Krevelen theory. The block copolymer with the highest PS content shows the highest tensile modulus and tensile strength, but also the smallest elongation at break. When silver nanoparticles treated with surfactant were added to the block copolymer matrices, each system studied shows higher mechanical properties due to the good dispersion and the good interface of Ag nanoparticles in the matrices. Furthermore, it has been shown that semi- empirical models such as Guth and Gold equation and Halpin-Tsai model can be used to predict the tensile modulus of the analyzed nanocomposites.

Recently we reported the critical content threshold of epoxidized polybutadiene (PBep) units to induce total miscibility between poly(styrene-b-butadiene) (SB) block copolymers (BC) and uncured epoxy resin.(20) In this work we investigate the different mechanisms involved through morphology development, depending on the content of epoxidized polybutadiene (PBep) in the initial mixture. PBep contents higher than, close below, or far below the critical threshold lead to long-range order nanostructures through reaction-induced microphase separation (RIMS) of PS block, a combination of both self-assembly and RIMS leading to vesicles or long wormlike micelles with a bilayered structure, or macroscopic phase separation, respectively. Nanoindentation was employed to identify the microphase-separated domains. Epoxy matrix can be significantly toughened for high BC contents in both prior to or through curing microphase-separated mixtures. Phase-separated domain size but also extent of interactions between them and...

The goal of this work has been the synthesis of novel materials based on a biodegradable polycaprolactone-block–polytetrahydrofurane-block–polycaprolactone diol (PCL-b–PTHF-b–PCL). The segmented thermoplastic polyurethanes (STPU) have been synthesised in bulk without catalyst at different molar ratios and their characterization has been performed by different techniques. The physic-chemical interactions, responsible for the unique polyurethane properties, have been evaluated by total attenuated Fourier transform infrared spectroscopy (ATR-IR) in the amide I region using a Gaussian deconvolution technique and, on the other hand, atomic force microscopy (AFM) has been employed to determine the phase microstructures. The effect of increase the hard segment content (HS) has been discussed from the viewpoint of the miscibility of hard and soft segments, analyzed by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). The influence of HS content on the microstructure–mechanical property relationships has also been investigated. Special attention has been focused on the wettability of the samples, measured through water contact angle measurements (WCA), to determine the tendency for biocompatibility of the samples.

Novel thermoresponsive hybrid inorganic/organic thermosetting materials based on hydrophobictitanium dioxide nanoparticles and amphiphilic poly(styrene- b -ethylene oxide) block-copolymer-dispersed 4′-(hexyl)-4-biphenyl carbonitrile liquid crystals were prepared and characterized. The obtained results confirm thatthese multiphase materials maintain thermo-optical properties of incorporated liquid crystals and show gooddispersion of the titanium dioxide, which the microphase separated within the HBC/PS-block. Moreover, well-dispersed nanoparticles spontaneously form well-defined highly dense arrays of titania nanodots located in theinterface between the epoxy matrix and the microphase-separated HBC/PS-block, which, combined with the factthat TiO 2 nanoparticles maintain their conductive properties in the investigated systems, can lead to the generationof novel materials with interesting specific properties. Introduction The manufacture of metal-based nanoarchitectured materials(such as nanoparticles, nanorods, nanowire, or nanosheets) iscurrently an active research field because of their potentialapplications in very wide areas of nanotechnology such aselectronics, magnetics, optics, photonics, and electrochemistryor catalysis.

Molecular dynamics of diglycidyl ether of bisphenol A (DGEBA) epoxy resin modified with an epoxidized poly(styrene-b-butadiene) (SepB) linear block copolymer has been monitored during cure and microphase separation process by dielectric relaxation spectroscopy (DRS) for wide frequency and temperature ranges. Different primary and secondary relaxation processes have been analyzed for neat components and ternary mixture. Relaxational behaviour has been modelled with Havriliak–Negami, Vogel–Fulcher–Tammann and Arrhenius equations and fitting parameters and their evolution have been obtained. The retention of the epoxidized poly(butadiene) (PepB) block in the epoxy-rich phase during all the polymerization process, previously detected by our group with atomic force and transmission electron microscopies, has been confirmed by dielectric relaxation spectroscopy. The evolution of molecular dynamics during the polymerization process of the epoxy resin in the ternary system indicates a change in the trend of the main relaxation at times that agree with phase separation detected by rheology.

BACKGROUND: The goal of this work was to establish the minimum degree of epoxidation needed to develop nanostructured epoxy systems by modification with poly(styrene-block-butadiene-block-styrene) (SBS) triblock copolymers epoxidized to several degrees, and also to investigate the effect of polystyrene (PS) content on the final morphologies. By using two SBS copolymers, the influence of the weight ratio of the two blocks on the generated morphologies and mechanical properties was also analysed. RESULTS: Nanostructured thermosets were effectively obtained through reaction-induced microphase separation of PS blocks from the matrix. A minimum of 27 mol% of epoxidation, which corresponds to 4.8 wt% of epoxidized polybutadiene (PB) units in the overall mixture, was needed to ensure nanostructuring of final mixtures and thus their transparency. Hexagonally ordered nanostructures were achieved for PS contents of around 16–20 wt%, which agrees with our previous results for mixtures with other SBS copolymers with different ratios between blocks. The fracture toughness of the epoxy matrix was improved or at least retained with mixing. CONCLUSION: The degree of epoxidation of PB blocks needed to switch epoxy/SBS mixtures from a macrophase-separated to a nanostructured state has been established. The generated morphologies in the epoxy systems are mainly dependent on the PS content in the mixture. Copyright © 2008 Society of Chemical Industry

Magnetic nanoparticles were studied to generate novel nanocomposites which maintain both magnetic properties of nanoparticles and self-assembly of amorphous block copolymer matrix. With this goal, iron oxide magnetic nanoparticles were modified with polystyrene (PS) brushes by atomic transfer radical polymerization (ATRP) to improve both the dispersion and the affinity of nanoparticles with one of the blocks of polystyrene-b-polybutadiene-b-polystyrene block copolymer. This way of preparation of nanocomposites opens new strategy to the generation of magnetic nanocomposites. The samples were characterized with the use of differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), rheological measurements, and atomic force microscopy (AFM).

Thermodynamic phase behavior was studied for polymer dispersed liquid crystal (PDLC) films consisting of blends of different thermoplastics such as poly (bisphenol A carbonate) (PC), poly(methylphenylsiloxane) (PMPLSi), poly(styrene-b-ethylene oxide) (PSEO) block copolymer, and low-molecular weight 4′-(hexyloxy)-4-biphenyl-carbonitrile (HOBC) liquid crystals. The phase diagrams of these PDLC systems were built up using thermal transitions determined by differential scanning calorimetry (DSC), transmission optical microscopy (TOM), and dynamic mechanical analysis (DMA). Final morphology of these PDLC films generated by temperature induced phase separation was monitored by TOM. The final morphology of HOBC blends with PC, PSEO, or PMPLSi could be modified by controlling the relative compositions resulting in PDLC systems with small and narrow size-distribution of nematic droplets, suitable for use in thermo-optical devices. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008