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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.

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.

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

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

Magnetic nanomaterials have been studied in order to generate novel nanocomposities that display both teh magnetic properties of the nanoparticles and the ability to self-assemble of the amorphous block copolymer matrix. Towards this goal, iron oxide magnetic nanoparticles have been modified with PS brushes by ATRP in order to improve both the dispersion and the affinity of the nanoparticles with one of the blocks of a polystyrene-block-polybutadiene-block-polystyrene block copolymer. This method of preparation of nanocomposites opens new strategies for the generation of magnetic nanomaterials. The samples are characterized using DSC and atomic and magnetic force microscopies. Macromol Rapid Commun

The free volume in epoxy systems based on diglycidyl ether of bisphenol-A (DGEBA) fully cured with aminic hardeners having different chemical structures has been studied by means of positron annihilation lifetimes spectroscopy. The results are compared with those obtained from the analysis of the macroscopic specific volume changes by using pressure-volume-temperature (PVT) experimental technique. An excellent correlation between the volumes measured at macro and nanoscales was found for the epoxy systems fully cured with aminic hardeners. On the other hand, a systematic study on the dependence of the volumes at nano-scale in epoxy systems cured with two selected aminic hardeners at different pre-cure temperatures revealed that the pre-cure temperature, as well as, the structure of the hardeners governs the packing of the molecular chains of the epoxy network and its influence in the volume and number density of the nanoholes. In the second part of this work, a systematic study of the effect of several epoxidation degrees of butadiene block in a commercial polystyrene-polybutadiene star block copolymer (SB) has been carried out to control nano-ordering in thermosetting epoxy systems. For this purpose, blends of DGEBA cured with 4,4′-methylenebis(3-chloro-2,6-diethylaniline) (MCDEA) containing 30 wt% neat SB and several epoxidized SB star block copolymers have been synthesized. At low epoxidation degrees, interactions with the epoxy matrix are not sufficiently favorable and macroscopic phase separation takes place, leading to a phase-inverted morphology where the block copolymer may become the matrix. For high epoxidation degrees, however, nanostructured thermosetting systems, being the epoxy-rich phase the matrix of the blends, have been obtained. It has been proved that, in blends containing SepB61 and SepB76 star block copolymers, the copolymer self-assembles into a well-defined hexagonally ordered structure, where cylinders are formed by PS arranged in an epoxy matrix containing both epoxidized and non-epoxidized butadiene units. SAXS experiments show that there are not strong differences in the long spacing between the different systems because the repeated distance between PS cylinders for all the blends is around 41-42 nm. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Thermally reversible nanostructured thermosetting materials are prepared for the first time by modification of an epoxy resin with 5 wt.-% of an amphiphilic polystyrene-block-poly(ethylene oxide) block copolymer (PSEO) and 30 wt.-% of a low-molecular-weight liquid crystal, 4'-(hexyl)-4-biphenylcarbonitrile (HBC). The epoxy system modified with 5 wt.-% PSEO amphiphilic copolymer self-assembles into spherical microdomains with a size distribution between 32 and 45 nm in diameter. Under the same conditions, the modification of an epoxy system with 5 wt.-% PSEO and 30 wt.-% HBC leads to a micro-phase separated PS-rich domains embedded in a HBC phase. The morphology of this nanostructured thermosetting system consists in a higher amount of spherical microdomains of PSEO/HBC with the size distribution between 40 and 75 nm in diameter. This implies that the separation of the PS-rich phase provokes the separation of the liquid crystal and allows one to obtain a novel thermally switchable smart material.

The functionalization of nanoparticle surfaces is required to improve the dispersion of an inorganic material inside an organic matrix. In this work, polystyrene (PS) brushes were grown on the surface of iron oxide magnetic nanoparticles with atom transfer radical polymerization and a grafting-from approach. After polymerization, the magnetic nanoparticles had a graft density of 0.9 PS chains/nm(2). A sacrificial initiator was used to obtain a satisfactory result for the control of the polymerization, as its addition had to generate a sufficient concentration of persistent radicals (deactivator). A variety of techniques, such as Fourier transform infrared spectroscopy, thermogravimetric analysis, gel permeation chromatography, water contact-angle measurements, and atomic force microscopy, were used to characterize the nanoparticles. (c) 2007 Wiley Periodicals, Inc. Journal of Polymer Science Part a-Polymer Chemistry

A key problem with nanomaterials is the difficulty of controlling the dis- persion of nanoparticles inside an organic medium. To overcome this problem, func- tionalization of the nanoparticle surface is required. Poly(methyl methacrylate) (PMMA) brushes were grown on the surface of iron oxide magnetic nanoparticles with atom transfer radical polymerization and a grafting-from approach. Modified magnetic nanoparticles with a graft density of 0.1 PMMA chains/nm 2 were obtained. Cu(II), used as a deactivating complex, allowed good control of the polymerization along with a narrow polydispersity of the polymer chains. The functionalized magnetic nanopar- ticles were characterized with Fourier transform infrared spectroscopy, thermogravi- metric analysis, gel permeation chromatography, and atomic force microscopy. V C 2007

Epoxy-based blends containing poly(ethylene oxide)-co-poly(propylene oxide)-co-poly(ethylene oxide) (PEO–PPO–PEO) block copolymers with different PEO/PPO molar ratios have been investigated in order to analyze the effect of the generated morphologies and interactions between components on the mechanical properties of the blends. Mechanical, morphological and dynamic mechanical analyses indicate that the observed increase of flexural modulus can be related to the decrease of free volume. In modified systems that remain miscible, an increase of flexural modulus, strength and fracture toughness can be observed. Also, macrophase- and microphase-separated systems show an increase of fracture toughness but not of flexural modulus and strength at low contents of block copolymers. Copyright © 2007 Society of Chemical Industry

Homogeneous solutions of syndiotactic polystyrene (sPS) in diglycidylether of bisphenol A (DGEBA), containing 2.5, 5 and 7.5 wt % of thermoplastic with or without 0.5 and 1 wt % of poly(styrene-b-ethylene oxide) (PS-b-PEO) block copolymer, were polymerized using a stoichiometric amount of an aromatic amine hardener, 4,4′-methylene bis (3-chloro-2,6-diethylaniline) (MCDEA). The dynamic-mechanical properties and morphological changes of sPS-(DGEBA/MCDEA) compatibilized with different amount of PS-b-PEO have been investigated in this paper. The addition of the block copolymer produced significant changes in the morphologies generated. The size of the dispersed spherical sPS spherulites does not change significantly, but less spherulites of sPS appeared upon network formation in the systems with compatibilizer, what means that addition of compatibilizer in this system delayed crystallization of sPS in sPS-(DGEBA/MCDEA) systems and change phase separation mechanism from crystallization-induced phase separation (CIPS) and reaction-induced phase separation (RIPS) almost only to RIPS. Moreover, PS-b-PEO with higher molecular weight of PS block seems to be a more effective compatibilizer than one with lower molecular weight of PS block. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 479–488, 2006

The rheological behavior of thermosetting epoxy mixtures modified with thermoplastic syndiotactic polystyrene (sPS) was monitored during the curing of the epoxy resin. The selected thermosetting system was diglycidyl ether of bisphenol A cured with 4,4′-methylene bis(3-chloro-2,6-diethylaniline) in the presence of various compositions of sPS (from 2.5 to 12.5 wt %). The storage and loss shear moduli of the systems were monitored during network formation. The validity of the Winter–Chambon criterion for the accurate determination at the gelation point from rheological data was demonstrated. The influence of the sPS concentration on the dynamic rheological properties of the samples was investigated. The experimental data showed that at sPS concentrations lower than 7.5 wt %, phase separation induced a quick increase in the viscosity, which was related to a crystallization-induced phase separation of sPS. For sPS concentrations higher than 7.5 wt %, near the phase-inversion composition, the rheological behavior of the mixtures was characteristic of a cocontinuous structure. After the viscosity jumped at the onset of phase separation, a decrease in the viscosity was found, and later on, the viscosity increased again because of gelation. Additionally, the influence of the cure temperature on the rheological properties was studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2348–2355, 2006

The main aim of this research was the generation of new intelligent materials, in this case thermoreversible material, based on an epoxy matrix modified with liquid crystal for optoelectronic application. The samples were prepared by the reaction-induced phase separation (RIPS) of a solution of 4′-(hexyloxy)-4-biphenyl-carbonitrile (HOBC) and polystyrene (PS) in diglicydylether of bisphenol-A epoxy resin (DGEBA). The systems were cured with a stoichiometric amount of an aromatic amine hardener, 4,4′-methylene bis(3-chloro-2,6-diethylaniline) (MCDEA). Taken into account results obtained by differential scanning calorimetry (DSC) and transmission optical microscopy (TOM) equipped with a hot stage it was found that depending on morphology generated by RIPS of HOBC/thermoplastic particles in the epoxy matrix thermally reversible light scattering (TRLS) material can be obtained. Copyright © 2006 John Wiley & Sons, Ltd.

Nanostructured thermosetting materials were prepared by modification of an epoxy resin with 30 wt.-% epoxidized polystyrene-block-polybutadiene copolymer (PS-b-PepB). The copolymer self-assembles into a well-defined hexagonal nanoordered structure, of around 30-nm diameter, thus establishing its use as structure-directing agent to generate nanostructured thermosetting materials. The study confirms pathways towards tailoring interactions betwwen thermosetting matrices and immiscible block copolymers by using the concept of unctionalization to build nanostructured polymer matrices.

The phase separation and crystallization processes occurring in a semicrystalline thermoplastic-(epoxy/amine) system were studied by using dynamic oscillatory rheometry and differential scanning calorimetry (DSC). Moreover, a transmission optical microscope (TOM) equipped with a hot stage was used to get a direct representation of the obtained morphologies at different times during the phase separation and crystallization processes. The morphology of the cured samples was additionally studied by atomic force microscopy (AFM). The selected thermoset system was diglicydylether of bisphenol-A (DGEBA) cured with 4,4′-methylene bis (3-chloro-2,6-diethylaniline) (MCDEA) and modified with syndiotactic polystyrene (sPS). In the initially miscible semicrystalline thermoplastic/thermoset system, phase separation is induced by the curing reaction (reaction-induced phase separation [RIPS]) and by crystallization of the thermoplastic (crystallization induced phase separation [CIPS]). Both phenomena take place almost at the same curing time and both have strong influence on the morphology of cured samples. POLYM. ENG. SCI. 45:303–313, 2005. © 2005 Society of Plastics Engineers.

Hybrid organic/inorganic thin film nanocomposites based on poly(styrene)-b-poly(butadiene)-b-poly(methyl methacrylate) triblock copolymer and silver nanoparticles are prepared and characterized. In order to improve the compatibility of nanoparticles with the polymeric matrix, their surface is modified with dodecanethiol surfactant, which enables a good dispersion of nanoparticles through the triblock copolymer, without the formation of aggregates. By atomic force microscopy (AFM), the dispersion level of nanoparticles is analyzed, together with their effect on the thin film surface morphology, for nanocomposites up to 15 wt% of nanoparticles. Dielectric properties of nanocomposites are studied by dielectric relaxation spectroscopy (DRS), analyzing the effect of nanoparticles on dielectric properties. Even if conductivity and permittivity of composites increase with nanoparticle content, percolation threshold is found to be at around 15% in volume. Morphologically analyzed nanocomposites are, in this way, below the threshold.

A key problem with nanomaterials is the difficulty of controlling the dispersion of nanoparticles inside an organic medium. To overcome this problem, functionalization of the nanoparticle surface is required. Poly(methyl methacrylate) (PMMA) brushes were grown on the surface of iron oxide magnetic nanoparticles with atom transfer radical polymerization and a grafting-from approach. Modified magnetic nanoparticles with a graft density of 0.1 PMMA chains/nm(2) were obtained. Cu(II), used as a deactivating complex, allowed good control of the polymerization along with a narrow polydispersity of the polymer chains. The functionalized magnetic nanoparticles were characterized with Fourier transform infrared spectroscopy, thermogravimetric analysis, gel permeation chromatography, and atomic force microscopy. (c) 2007 Wiley Periodicals, Inc. Journal of Polymer Science Part a-Polymer Chemistry