PS Matrix Research Articles

Preparation, characterization and thermal properties of the PS+Si based polymer nanocomposites

Polymer nanocomposites based on polystyrene and polycrystalline Si nanoparticles have been successfully synthesized using the solution-casting method. The scanning electron microscope and x-ray diffraction methods show that the Si nanoparticle size in the obtained nanocomposite was up to 50 nm. The thermostability of the obtained nanocomposite was studied depending on the concentration of Si nanoparticles in the PS matrix. It was found that Si nanoparticles that are distributed homogeneously in the polymer matrix act as a thermal barrier. By adding 3% Si nanoparticles into polystyrene polymer, the thermal degradation temperature of PS increases by 20°, and the decomposition rate reduces from −42,460 mg/min to −35,099 mg/min. In addition, it was shown that Si nanoparticles do not affect the PS glass transition temperature, which explains that the porous Si does not reduce the free volume for the polymer molecules to move. The polymer macromolecules just are adsorbed on the porous silicon surface, which partially limits their mobility.

Dysprosium-enriched polymer nanocomposites: Assessing radiation shielding and optical properties

This paper includes a comprehensive analysis of the radiation shielding, optical properties, and structural makeup of polymer composites that contain Dy2O3 additions. XRD-pattern investigates the effect of loading Dy2O3 content on PS, with the average crystallite size of Dy2O3 decreases from 39 nm to 30 nm as Dy2O3 increases from 2.5 to 7.5 wt% in the PS matrix. The optical properties of the nanocomposites showed that with the increase in the Dy2O3 content, the transmittance, as well as the direct and indirect band gap, decreased. The EgIndirect bandgap decreased from 3.1 to 2.75 eV with a Dy2O3 increase from 0 to 7.5 wt%, while the Egdirect Bandgap reduced from 4.6 to 4.35 eV. While the Urbach energy Eu and the refractive index increase, Eu rises from 0.48 to 0.60 e V, and n improves from 1.4 to 1.78 from 0 to 7.5 wt%. In order to conduct an accurate analysis of the gamma-ray attenuation capabilities of the selected new polymer composites, these composites were manufactured with varying proportions of the additive components. With the assistance of a Na(Tl) detector, experimental assessments were carried out on the gamma rays throughout a broad spectrum of photon energies, ranging from 81 keV up to 1416 keV. The sample encased in PS/Dy7.5 demonstrates excellent radiation attenuation, and it is important to note that this novel polymer shielding material does not include any hazardous components.

Phase inversion detection in immiscible binary polymer blends via zero‐shear viscosity measurements

AbstractIn the present work, we demonstrate that zero‐shear viscosity is a sensitive rheological function to detect phase inversion in immiscible binary polymer blends characterized by a viscosity ratio larger than one. The phase inversion of poly(propylene) (PP)/low‐density poly(ethylene) (LDPE) and poly(styrene) (PS)/LDPE, at various compositions, was assessed via our novel approach. For both blends, three distinctive regions could be determined through zero‐shear viscosity measurements; the LDPE matrix, the co‐continuous phase, and the PS or PP matrix. For PP/LDPE blends, the co‐continuous structure was between 50 and 75 wt.% PP, and for PS/LDPE blends the co‐continuous structure was between 45 and 75 wt.% PS, in agreement with scanning electron microscopy analysis, empirical model predictions, and literature data.Highlights Phase inversion revealed via viscosity measurements. Limitations of linear viscoelastic models for immiscible blends assessed.

Synthesis of cobalt nanoparticles in polystyrene matrix enhanced optical, dielectric, and magnetic properties

Recently, the development of particles fortified polymer composites has grown significantlydue to their intelligent uses in many fields.Cobalt nanoparticles' impact on the dielectric, optical, and magnetic properties of cobalt/polystyrene (Co/PS) nanocomposite films has been investigated. Co-NPs were preparedusing the reduction method and loadedintothepolystyrenematrixwith different concentrations(2, 5, 8, and 10 wt.%),forming nanocompositefilms. X-ray diffraction XRD was used to describe the structure of the produced films. The results showed a hexagonal (hcp) structure with ε phase of the Co-NPs in the PS matrix. The topography of the cross-section of nanocomposite films was scanned through a field emission electron microscope (FE-SEM). The high-resolution transmission electron microscope (HR-TEM) was used to examine the morphology of the produced Co-NPs. Zetasizer considered the charge and particle size distribution of the prepared Co-NPs powder. At room temperature, dielectric spectroscopy looked at the dielectric characteristics over a frequency range from 10−1 - 107 Hz. The UV analyzed the optical properties of nanocomposite films–VIS technique. The optical bandgap of the nanocomposite films is a direct allowed transition and decreases from 4.51 to 3.69e, which increases the absorption coefficient. A vibrating sample magnetometer (VSM) was used to measure the magnetic hysteresis loops of the produced films at room temperature. The ferromagnetic behavior of all samples was evident, and there was an apparent magnetic hysteresis. All samples exhibited high coercivity, where the exchange bias decreased from 28.02 Oe to 1.42 Oe with increasing Co wt% in PS. The present work found that the Co/PS nanocomposite films loaded with various concentrations of Co-NPs and tuned properties may be suitable for use in electrical energy storage, photonic devices, and some magnetic applications, such as spintronic devices.

Single-molecule detection of a terrylenediimide-based near-infrared emitter.

Environment-sensitive fluorescent agents with near-infrared (NIR) emission are in great demand owing to their applications in biomedical and quantum technologies. We report a novel NIR absorbing (λ Abs max = 734 nm) and emitting (λ Fl max = 814 nm) terrylenediimide (TDI) based donor-acceptor chromophore (TDI-TPA4), exhibiting polarity-sensitive single-photon emission. By virtue of the charge transfer (CT) character, ensemble level measurements revealed solvatochromism and NIR emission (ϕ Fl = 26.2%), overcoming the energy gap law. The CT nature of the excited states is further validated by state-of-the-art fragment-based excited state theoretical analysis. To mimic the polarity conditions at the single-molecule level, TDI-TPA4 was immobilized in polystyrene (PS; low polar) and poly(vinyl alcohol) (PVA; high polar) matrices, which enables tuning of the energy levels of the locally excited state and charge-separated (CS) state. Minimal blinking and prolonged survival time of the TDI-TPA4 molecule in the PS matrix, in contrast to the PVA matrix, possibly confirms the implication of the energy gap law and polarity sensitivity of TDI-TPA4. The existence of the CT state in nonpolar and CS state in polar solvents was confirmed by transient absorption measurements in the femtosecond regime. The current work sheds light on the design principle for NIR single-photon emitting organic chromophores for deep tissue imaging and probing the nanoscale heterogeneity.

Nanoscale Periodic Modulation of Doping over Large Areas with Block Copolymer Lithography and Ion Implantation

Whenever periodic patterning at the nanoscale over a large surface is required, block-copolymers (BCPs) represent an extremely attractive alternative for lithography1 and nano-templating,2 because of the low cost, if compared to conventional photolithography,3 and the high throughput, if compared to serial lithographic processes, such as electron beam lithography (EBL).4 Despite the relatively simple structure of BCPs, two different linear homopolymers linked to each other at one end by a covalent bond, when annealed above the glass transition temperature, they spontaneously microphase separate generating a variety of periodic nanostructures. The periodicity (L0 ) of the microdomains can be varied in the 10 – 100 nm range by properly adjusting the molecular weight and the interaction parameter of the two blocks.5 In this work, the combination of BCP lithography and ultra-low energy implantation of phosphorus ions at high fluences is investigated to promote a periodic modulation at the nanoscale of the concentration of dopant impurities over the near-surface layer of a silicon substrate.For the fabrication of the masks, two different poly(styrene-b-methyl methacrylate) (PS-b-PMMA) BCPs were used, to obtain two different geometries: the first with out of plane hexagonally packed PMMA cylinders, with an average diameter of 22 nm and center-to-center distance of 35 nm (Figure 1A) , and the second with out of plane lamellae having a periodicity of 28 nm (Figure 1B). The thickness of the BCP films was 35 nm thick. In addition, a graphoepitaxy protocol was implemented to obtain different sets of perfectly aligned 20 μm long parallel lamellae. A mesoporous soft mask can be readily obtianed by selective removal of PMMA cylinders with UV light and acetic acid. Conversely, a different process is required to avoid the collapse of the PS lamellae. Using Sequential Infiltration Synthesis (SIS),6 Al2O3 is incorporate into the PMMA phase of the BCP film. Upon the removal of the organic material by a mild O2 plasma cleaning, a nanostructured Al2O3 layer, that perfectly matches the PMMA pattern, remains on the substrate (Figure 1B).Phosphorus ions were implanted through the soft masks into the Si substrate operating at ultra-low energy (3 keV) to prevent the degradation of the polymeric film and reduce P penetration (10 nm) into the Si substrate. Additionally, high implantation doses are considered, to induce local amorphization of the silicon substrate. In this way Solid Phase Epitaxial Regrowth (SPER) can be exploited to recover the crystallinity of the substrate by thermal treatments at relatively low temperatures.7 During the SPER process the phosphorus atoms are substitutionally incorporated into the silicon lattice preserving their spatial confinement.AFM morphological analysis and ToF-SIMS depth profiling of the mask confirm the capability of the PS and alumina matrix to properly shield the low energy phosphorus ions in the dose range under investigation. AFM and ToF-SIMS characterization of the samples upon removal of the mesoporous template demonstrated that the P ions were effectively implanted into the Si substrate through the mask, leading to localized implantation (Figure 1C - 1E). Raman spectra suggested the presence of a thin layer of amorphous Si in the implanted samples and subsequent recrystallization after the annealing. By specific SPM measurements, it was possible to compare the morphology, the map of surface potential and the map of conductivity of the samples. The analysis of the Si surface after implantation through the mask with cylindrical pores and activation of the P is reported (Figure 1F, 1G). Small variations of the surface potential that perfectly match the implanted regions were obtained, suggesting a local modification of the electrical properties of Si. This result is also supported by conductivity measurements and finite element method (FEM) simulations. Further results will be presented, to investigate the electrical properties of the samples as a function of the implanted P dose and of the geometry of the mask.(1) Feng, H. et al., Nat. Mater. 21, 1426–1433 (2022).(2) Chai, J. & Buriak, J. M., ACS Nano 2, 489–501 (2008).(3) Levinson, H. J., Jpn. J. Appl. Phys. 61, (2022).(4) Yang, X. M. et al., ACS Nano 3, 1844–1858 (2009).(5) Seguini, G. et al. Soft Matter 16, 5525–5533 (2020).(6) Tseng, Y. C. et al. J. Phys. Chem. C 115, 17725–17729 (2011).(7) Luce, F. P. et al., Nucl. Instruments Methods Phys. Res. Sect. B Beam Interact. with Mater. Atoms 370, 14–18 (2016). Figure 1

Nanoporous Double-Gyroid Structure from ABC Triblock Terpolymer Thick Films

The creation of nanostructured materials with a triply periodic minimal surface (TPMS), defined as a zero mean curvature surface having periodicity in three-dimensional space, is an emerging solution to optimize transport (i.e., the ion-conductivity and hydraulic permeability) through the next-generation of electrolyte and ultrafiltration (UF) membranes. Here, we used an amphiphilic ABC-type block copolymer (BCP) (namely, polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO)) to generate symmetric thick films (~8 μm) composed entirely of a TPMS-based structure, consisting of a PS matrix with a double gyroid (DG) minimal surface and hydrophilic stimuli-responsive (P2VP/PEO) nanochannels. To produce the core/shell DG-structured monoliths, we used a process combining the nonsolvent-induced phase separation (NIPS) process with a solvent vapor annealing (SVA) treatment. From such symmetric ABC-type BCP-thick films generated by NIPS-SVA, a mean hydraulic permeability as high as 514 L h-1 m-2 bar-1 was measured. This mean value was revealed to be nearly equal to that of asymmetric PS-b-P2VP-b-PEO membranes manufactured by NIPS, which have a substructure with an implicit irregular and random distribution of the internal pore structure and a skin layer with P2VP/PEO nanopores arranged into a hexagonal array.

Covalent functionalization of activated MoS2 via using alkyl sulfide and their utilization in polymeric composites with mechanical and thermal property enhancements

AbstractRecently developed covalent functionalization of chemically exfoliated MoS2 (typically in alkyl lithium) allows the formation of chalcogenide‐carbon bonds by reacting with organohalides and aryl diazonium salts. We herein develop a novel method for the covalent functionalization of MoS2 to yield dodecylated MoS2 via reductive activation in a strongly reducing sodium‐naphthalene solution and using alkyl sulfide as an electrophile. Dodecylated MoS2/polystyrene (PS) composites fabricated by solution casting method. Dodecyl chains are grafted successfully onto MoS2 nanosheets, which gives rise to the exfoliation level of few‐layer thickness and matched compatibility with the host polymeric matrix. The inclusion of dodecylated MoS2 at a concentration of 1.0 wt% yields a substantial improvement in both Young's modulus and tensile strength, with a 106.7% increase and a 67% enhancement, respectively, as compared to the performance of pure PS. The enhanced mechanical characteristics can be credited to the uniform dispersion of dodecylated MoS2 within the PS matrix and enhanced interfacial interaction between the PS material and the filler. The composites demonstrate a significant increase in their glass transition temperature (Tg). Notably, the dodecylated MoS2/PS (1.0 wt%) composite exhibits a 59.8% elevation in storage modulus when compared to pure PS. The coke yield of dodecylated MoS2/PS (1.0 wt%) reaches 2.7%, much larger than the value (only 0.2%) for pure PS. The novel functionalization might expedite the applications of molybdenum disulfide in diverse fields.Highlights A novel method for the covalent functionalization of MoS2. Dodecylated MoS2/PS composites were fabricated via solution casting method. Ultrathin structure of MoS2 nanosheets was obtained after functionalization. Composites improvement in Young's modulus and tensile strength compared to PS. The composites show significant enhancements in Tg.

Novel cobalt lead ferrite (CPFO)/Ps nanocomposites with enhanced structure, optical and dielectric properties

Hexa-spinel ferrite nanoparticles of Cobalt Lead Ferrite (CPFO) were prepared by a flash auto combustion method, while xCPFO/PS (x = 0, 2.5, 5, and 7.5 wt%) nanocomposite films were synthesized by casting method. The diffraction pattern and Rietveld refinement of CPFO nanoparticles proved that they have a face-centred cubic spinel and a hexagonal structure. HRTEM micrographs of cobalt lead ferrite (CPFO) nanoparticles show an average particle size of around 30 nm. FESEM cross-section images of CPFO/PS nanocomposite films showed CPFO nanoparticles dispersed in the PS matrix. All optical characteristics of the synthesized nanocomposite films, including absorbance, transmittance, direct and indirect energy band gap, Urbach energy, excitation coefficient, and refractive index, were investigated using a UV-visible spectrophotometer examination. The direct optical energy band gap lowered from 4.533 eV to 4.368 eV, and the indirect energy optical bandgap lowered from 4.337 eV to 4.146 eV, while the Urbach energy increased from 0.103 eV to 0.209 eV with increasing the nanofillers from 0 to 7.5 wt%. Broadband dielectric spectroscopy was used over a wide frequency range (0.1 Hz–1 MHz). The dielectric real permittivity (ε′), the dissipation factor tan (δ) and the electric modulus (M′&M′′) measurements were studied. CPFO nanoparticles’ addition significantly enhanced the dielectric real permittivity (ε′), the dissipation factor tan (δ), and the ac conductivity of all nanocomposites.

Tailoring confined CdS quantum dots in polysulfone membrane for efficiently durable performance in solar-driven wastewater remediating systems

In this work, CdS quantum dots (QDs) were successfully confined in polysulfone membrane (PSM) to develop a photoactive membrane under solar illumination that was suited in wastewater remediating system. The CdS@PSM membranes were prepared using the nonsolvent induced phase separation (NIPS) approach. Optical measurements show the confinement of CdS quantum dots (QDs) in the PS matrix within the narrowest band gap (2.41 eV) at 5 wt% loading. PS has two strong emission peaks at 411 and 432 nm due to photoelectron-hole recombination on pure PSM's surface. Adding 1 wt% CdS QDs to PSM reduced the earlier peak and blue-shifted the latter, within the appearance of three emission peaks attributed to the near band-edge emission of confined CdS QDs. Overloading CdS reduced all emission peaks. Moreover, fluorimetric monitoring of •OH radicals indicates that PSM produces the least amount of photogenerated •OH radicals while CdS@PSM(5 wt%) achieved the highest productivity. Examining the developed membranes in detoxifying methylene blue (MB) from aqueous solution of natural pH 8.1 showed weak adsorption in dark over 90 min of contact while switching to solar illumination significantly photodegrade MB where the degradation efficiency starts from 49% for pure PSM to 79% for CdS@PSM(5 wt%). Influence of pH was found crucial on photodegradation efficacy. Acidic pH 3 showed the weakest photodegradation efficacy, while the alkaline pH 12 was 18.88 times more effective. The used CdS@PSM (5 wt%) was successfully photo-renovated by soaking in 10 mL of NaOH solution under Solar illumination for 15 min to be used in 4 consecutive photodegradation cycles with insignificant decrease in efficacy. These findings are promising and could lead to a high-efficiency, sustainable photocatalytic suite.

Stabilization and solidification mechanism of Pb in phosphogypsum slag-based cementitious materials

This study involves the use of solid waste (GGBS and phosphogypsum) in combination with lime to prepare a phosphogypsum-slag based cementitious matrix (PS) for solidifying/stabilizing Pb (II). Effective Pb-stabilization was achieved regardless of using different contents of raw materials, the compositions of 60% GGBS, 35% phosphogypsum and 5% CaO had excellent compressive strength and low metal leaching concentration, and the mechanism of solidification/stabilization on heavy metals had been investigated. XRD patterns revealed that the hydration products of PS were ettringite (AFt), calcium silicate hydrate(C-S-H) and gypsum. Hydration heat test and TGA analysis showed that the hydration process of PS matrix was retarded after the addition of Pb, and the production (AFt and C-S-H) was reduced. FTIR, NMR and SEM-EDS analysis showed that there was no substitution of Pb to Si and Al, and PS solidified/stabilized Pb was mainly achieved by physical means. Such as the physical encapsulation and adsorption of Pb by ettringite and calcium silicate hydrate, the substitution of Pb to Ca ion, and the binding of Pb by covalent bond. PS matrix can stabilize Pb through the above ways. Lead phosphate precipitation may contribute to the reduction of metal leaching concentration.

Valorization of Lignocellulosic Wastes Material for Efficient Adsorption of a Cationic Azo Dye and Sludge Recycling as a Reinforcement of Thermoplastic Composite

This work explored the adsorption of Malachite Green (MG) dye by Acorn Pericarp (AP) in the context of biomass valorization. The Acorn Pericarp was analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction. The adsorption capacity under optimal experimental conditions was studied at different adsorbent doses, the initial concentration times of the dye and pH. The results presented in this work on the adsorption kinetics of MG showed that the pseudo-first-order model (R2 = 0.9971) better described the adsorption kinetics at 10−5 M. The experimental isotherms showed that Acorn Pericarp adsorption followed the Langmuir isotherm model (R2 = 0.9889). The thermodynamic study showed that MG adsorption is endothermic (ΔH° > 0) and spontaneous (ΔG° < 0). For a sustainable industry, the sludge was converted into reinforcement of polystyrene using in-situ polymerization with 10% by weight of filler. A morphological and structural analysis was performed using SEM and FTIR, the results of characterization showed that the AP sludge was incorporated well into the PS matrix.

Anisotropic nucleation and compatibilization of SiO2@PS Janus particles on expandable polystyrene

Inorganic particles usually used as nucleation agent to promote the polymer foaming of supercritical carbon dioxide. However, they are apt to agglomerating in the matrix, which is not conducive to obtaining foamed materials with homogeneous cells. Herein, the organic-inorganic Janus particles possess anisotropic chemical compositions were introduced into expandable polymer, in which two sides can perform compatibilization and nucleation independently. The dispersion of silica@polystyrene (SiO2 @PS) Janus particles (JPs) in PS matrix and the resulting improvements in rheological property, foaming performance, compressive strength of PS was discussed systematically. JPs could be uniformly dispersed in PS matrix attributed to the PS end of JPs. While the SiO2 end of JPs could act as heterogeneous nucleation agent and promote cell formation. Compared with PS foams, PS/JPs foams had smaller and more uniform cell sizes, leading to better compressive properties, i.e. the compressive strength of PS/JPs-5% foams at 100 °C, 110 °C and 120 °C increased by 37.4%, 60.6% and 57.9%, respectively. This work demonstrates that JPs are a novel nucleation and compatibilizer for making polymer foams with optimal cell structure and compressive property.

Thin film poly(vinyl alcohol)-polysulfone composite membranes based on recycled polysulfone: salt separation performances.

Poly(vinyl alcohol) (PVA)-coated membranes on polysulfone (Ps) (Memb-Pv) were cross-linked using the dibasic maleic acid. The tailoring of membrane properties (viz. hydrophilicity, permeability) develops through the ester linkage due to cross-linking of PVA and maleic acid (MA). Series of Ps asymmetric membranes were prepared using the successive stages of phase inversion of Ps materials. The recyclability approaches of polysulfone (Ps) pertained. The characteristics and transport properties of all the membranes are evaluated. FTIR-ATR, scanning electron (SEM), and atomic force microscopy (AFM) are used for the structural characterization of the membranes. The salient features of Memb-Pv composite membranes support promising results in desalination. The work aimed to highlight the trade-off between the flux and selectivity of composite membranes' salts (bi-/monovalent) through the recycled Ps matrix. The number of recycling stages influences the salt separation performance. The sulfate rejection differs from Memb-IPv (93.26%) to Memb-IVPv (86.70%) for water-I matrix using 2500mg/L. The defluoridation potential of the membranes is also convincing. The defluoridation performance of Memb-IPv is 87% for 10mg/L. A significant dimension is added regarding salt separation performance's dependence on the water matrices' nature. The decrease in fluoride separation is ~ 1-3% for the water-2 matrix as the TDS increases.

Fabrication and characterization of a new flexible ionizing ray sensor based on lead tungstate (PbWO4)

In this study, a cost-effective, flexible ionizing ray sensor based on lead tungstate nanoparticles (PbWO4 NPs) was fabricated. PbWO4 NPs were successfully synthesized via the co-precipitation method. Synthesized NPs were embedded in a polystyrene matrix (PS) to form a composite film. The prepared samples' optical response and structural features were investigated under ultraviolet, 980 nm diode laser, and ion beam induced luminescence excitations, along with XRD, XPS, Raman, EDX-Mapping, FESEM, TEM, AFM, and FTIR measurements. Also, the ionizing radiation sensitivity of the prepared composite film was investigated using 241Am and 137Cs sources. XRD, XPS, FTIR, and EDX-Mapping elemental results showed characteristic peaks of PbWO4 and related elements in the samples. TEM image showed that NPs are approximately 37 nm in diameter. Using Monte Carlo simulation algorithm, the range of alpha particles passing through PbWO4 and PS individually were obtained to be∼21 and 30 μm, respectively which were in good agreement with FESEM images. The band gap energy of the prepared nanopowders was obtained to be 3.40 eV. AFM topography images of the composite film showed that PbWO4 NPs were incorporated into the PS matrix with a Root Mean Square (RMS) roughness of 29.23 nm. According to the measurements, the flexible PbWO4 film showed good luminescent stability for more than three days in the floating water, prominent blue-green centered at 400–500 nm visible regions with an energy transfer efficiency of 89.3% and high ionizing ray sensitivity of 80% which is comparable with commercial ZnS: Ag. The results indicate that prepared nanocomposite has the potential for practical applications in future optoelectronic fields and wearable displays.

Fabrication of Dimensional and Structural Controlled Open Pore, Mesoporous Silica Topographies on a Substrate.

Open pore mesoporous silica (MPS) thin films and channels were prepared on a substrate surface. The pore dimension, thickness and ordering of the MPS thin films were controlled by using different concentrations of the precursor and molecular weight of the pluronics. Spectroscopic and microscopic techniques were utilized to determine the alignment and ordering of the pores. Further, MPS channels on a substrate surface were fabricated using commercial available lithographic etch masks followed by an inductively coupled plasma (ICP) etch. Attempts were made to shrink the channel dimension by using a block copolymer (BCP) hard mask methodology. In this regard, polystyrene-b-poly(ethylene oxide) (PS-b-PEO) block copolymer (BCP) thin film forming perpendicularly oriented PEO cylinders in a PS matrix after microphase separation through solvent annealing was used as a structural template. An insitu hard mask methodology was applied which selectively incorporate the metal ions into the PEO microdomains followed by UV/Ozone treatment to generate the iron oxide hard mask nanopatterns. The aspect ratio of the MPS nanochannels can be varied by altering etching time without altering their shape. The MPS nanochannels exhibited good coverage across the entire substrate and allowed direct access to the pore structures.

Influence of the Grain Size on the Mechanical Behavior of a Nanostructured Poly(butyl methacrylate)–Polystyrene Diblock Copolymer

The morphology and mechanical properties of solution-cast poly(butyl methacrylate)–polystyrene (PBMA–PS) diblock copolymer films (Mn = 270 kg mol−1, 70 Vol.-% PS) prepared by using different solvents (cyclohexane, toluene, chloroform, and dioxane) are investigated in this study. All solvents except dioxane, which leads to PBMA cylinders in the PS matrix, result in lamellar morphologies. The grain size, however, by using cyclohexane, is —two to three times smaller compared to toluene and chloroform. The grain boundaries in PBMA–PS formed by the soft thermoplastic PBMA phase cause flaws in the material, which results in both small values of the tensile strength of cyclohexane-cast films (23 MPa) compared to toluene- and chloroform-cast ones (31–32 MPa) and low ductility.

Microcellular foams production from nanocomposites based on PS using MOF nanoparticles with enhanced CO2 properties as nucleating agent

The use of metal-organic frameworks (MOF) nanoparticles as nucleating agents in gas dissolution foaming processes is presented. In this work, MOF nanoparticles with three different particle sizes were synthetized and introduced in film composites based on polystyrene at 1 wt.%. The addition of nanoparticles with high affinity to CO2, which is the gas used as a physical blowing agent, can contribute to increase the nucleation efficiency in comparison with the classical heterogeneous route using non CO2-philic particles. Nanoparticles dispersion in solids and cellular structure in foams were studied as a function of the particle size and foaming parameters, studying for first time the impact of MOF nanoparticles on the nucleation by gas dissolution foaming. Nucleation efficiencies in the order of 10−2 were achieved for PS/MOF composites. In addition, the thermal stability of the cellular structure in the composites was enhanced regarding to PS matrix, preserving the cellular structure regardless the foaming temperature. Therefore, MOF nanoparticles have emerged as promising nucleating agents in foaming procedures.

Thermally and organomodified montmorillonite as effective regulators of the structure formation process in polypropylene/polystyrene blends

The influence of the concentration of thermally and organomodified montmorillonite on the processes of structure formation in a blend of polypropylene/polystyrene (PP/PS) was studied. It is established that in nanofilled compositions, as well as in the original, is formed a microfibrillar structure, the dimensional characteristics of which depend on the content of the additive and the method of its modification. The investigated clays by content (0.2–2.0) wt. % by weight of polypropylene have a compatibilizing effect in the blend of PP/PS, which reduces the average diameter of microfibers by 1.6 times and increases the homogeneity of their distribution by diameter: statistical indicators decrease (standard deviation, variance, coefficient of variation). The modifying effect of thermally modified clay is higher—the improvement of the dimensional characteristics of PP microfibers is achieved at its minimum content in the blend (0.2 wt. %). The formation of anisotropic PP structures in the PS matrix and the relaxation of the accumulated stresses at the exit of the molding hole is the main factor that causes high values of the coefficient of swelling of the extrudates (4.0–7.7). The change in the microstructure of the extrudates of nanofilled systems during spinning depends on the composition of the blend and the method of modification of montmorillonite. The average diameters of microfibers decrease from 2.2 μm (in the original blend) to (1.3–2.0) μm (in three-component) depending on the content of additives. The ability to regulate the microstructure of incompatible polymer blends by introducing additives of thermally and organomodified montmorillonite will contribute to the creation of nanocomposites with controlled morphology, as well as new fine-fiber materials with improved filtering characteristics.

Study of the ordered assembly morphologies of diblock copolymers on the same substrate.

With the development of frontier technology in emerging semiconductor processes, self-assembling (SA) and directed self-assembly (DSA) of block copolymers (BCPs) have attracted great attention from scientific researchers and become promising candidates for advanced photolithography. Using an optimal coating and baking process, highly ordered assembly morphologies (e.g., cylinder and lamella) of two BCPs in thin films were obtained without an additional topcoat material layer. Moreover, the whole experimental study also provides an optimal process for integrating the two BCPs into the same topographic guiding pattern substrate fabricated by electron beam lithography (EBL) to achieve specific self-assembly. This topographic guiding substrate achieves not only lamellar micro-domains aligned perpendicular to the sidewalls of trench edges but also cylindrical micro-domains (PMMA phase in a PS matrix) aligned parallel to trench edges respectively, which provides insights and valuable information for further applications in lithography and electronic devices.