Pore Size Values Research Articles

Comparative Analysis of Dry and Wet Porometry Methods for Characterization of Regular and Cross-Linked Virus Removal Filter Papers.

Pore-size distribution (PSD) is the most critical parameter for size-exclusion virus removal filters. Yet, different dry- and wet-state porometry methods yield different pore-size values. The goal of this work is to conduct comparative analysis of nitrogen gas sorption (NGSP), liquid-liquid and cryoporometry with differential scanning calorimetry (CP-DSC) methods with respect to characterization of regular and cross-linked virus removal filter paper based on cellulose nanofibers, i.e. the mille-feuille filter. The filters were further characterized with atomic force and scanning electron microscopy. Finally, the removal of the worst-case model virus, i.e. minute virus of mice (MVM; 20 nm, nonenveloped parvovirus) was evaluated. The results revealed that there is no difference of the obtained PSDs between the wet methods, i.e. DSC and liquid-liquid porometry (LLP), as well as no difference between the regular and cross-linked filters regardless of method. MVM filtration at different trans membrane pressure (TMP) revealed strong dependence of the virus removal capability on applied pressure. It was further observed that cross-linking filters showed enhanced virus removal, especially at lower TMP. In all, the results of this study highlight the complex nature of virus capture in size-exclusion filters.

Fabrication and characterization of waterborne polyurethane/silver nanocomposite foams

Nowadays the waterborne polyurethane (WPU) is a newly developed polymer foam material as a replacement for conventional organic solvent‐based polyurethane (PU). Nevertheless, the WPU foams exhibit some drawbacks such as inferior mechanical strength, low thermal and dimensional stability, which inhibits its large‐scale application at present. So a series of novel WPU/silver nanocomposite foams was successfully prepared by mechanical foaming method. The effect of silver nanoparticles (nano Ag) content on the morphology, thermal behavior, air permeability, water vapor transmission rate (WVT), mechanical, and antibacterial properties of WPU/Ag nanocomposite foams were systematically investigated. The results revealed that the nano Ag were uniformly dispersed in WPU matrix and facilitated cell growth, leading to enhanced mean pore size, thermal stability, air permeability, and WVT value of nanocomposite foams. About 122% improvement in the air permeability and 28% improvement in the WVT value were obtained when the nano Ag content extended from 0 to 4 wt%. It was found that the nano Ag content had great influence on tensile strength and elongation at break. When nano Ag content was 2 wt%, the nanocomposite foam exhibited the maximum tensile strength value of 1.26 MPa. Moreover, because of the addition of nano Ag, the nanocomposite foam showed bacteriostatic rate of 98.23% and 97.38% against Escherichia coli and Staphylococcus aureus, respectively. POLYM. COMPOS., 40:1492–1498, 2019. © 2018 Society of Plastics Engineers

Computer Tomography Based Structure Characterization of Expanded Intumescent Coatings for Fire Protection

Intumescent coatings are used to protect structural steel from fires. In this study, morphological characteristics of expanded and charred intumescent coatings, which is a key factor of its thermal insulating mechanisms, have been studied using a computer tomography (CT)-based analysis method. Specimens of the charred materials are prepared by a laboratory-scale mass-loss cone heating method for measuring thermal insulation performance. Three types of coatings are exposed to three constant incident heat fluxes (25 kW/m2, 50 kW/m2, and 75 kW/m2) for 2 h. The micro-CT scanning technology is applied on the charred materials to generate 3D reconstructed images with 20 µm resolution by ImageJ software. By using an image processing technique, the central region of each scanned 3D model is divided into three horizontal layers at different depths: top, middle and bottom. The morphological structure varies significantly with the type of coatings, the incident heat flux, and the depth in the char, but the median value of pore size (i.e. equivalent diameter) for all tested samples varies within a narrow range (0.352 mm to 0.424 mm). The qualitative morphological observations as well as the quantitative pore properties (i.e., 3D porosity, size distributions, and sphericity) are obtained. The present non-destructive structure analyses method is useful to assist in new formulation developments and to advance numerical modeling.

Control of Ion Transport in Sulfonated Mesoporous Polymer Membranes

We investigated proton conductivity and the permeability of monovalent cations across sulfonated mesoporous membranes (SMMs) prepared with well-defined pore sizes and adjustable sulfonic acid content. Mesoporous membranes with three-dimensionally continuous pore structure were produced by the polymerization-induced microphase separation (PIMS) process involving the reversible addition-fragmentation chain transfer (RAFT) copolymerization of styrene and divinylbenzene in the presence of a polylactide (PLA) macrochain transfer agent and subsequent PLA etching. This allowed us to control pore size by varying PLA molar mass. Postsulfonation of the mesoporous membranes yielded SMMs whose pore structure was retained. The sulfonic acid content was adjusted by reaction time. While proton conductivity increased with increasing ion exchange capacity (IEC) without noticeable dependence on the pore size, ion permeability was strongly influenced by the pore size and IEC values. Decreasing pore size and increasing IEC resulted in a decrease in ion permeability, suggesting that ions traverse across the membrane via the vehicular mechanism, through the mesoporous spaces filled with water. We further observed that the permeability of the vanadium oxide ion was dramatically suppressed by reducing the pore size below 4 nm, which was consistent with preliminary vanadium redox flow battery data. Our approach suggests a route to developing permselective membranes by decoupling proton conductivity and ion permeability, which could be useful for designing separator materials for next-generation battery systems.

Cerium-containing mesoporous bioactive glasses: Material characterization, in vitro bioactivity, biocompatibility and cytotoxicity evaluation

Abstract Bone defects due to trauma or diseases causing bone loss have led to an increased demand for new materials that have applications in therapies for bone pathologies. Mesoporous bioactive glasses (MBGs), based on 70SiO2-(26-x)CaO 4P2O5-xCeO2 (x = 0, 1 and 5 mol % for MBGS, MBGS1Ce and MBGS5Ce) were synthesized by evaporation-induced self-assembly (EISA) method. Ceria was selected due to its antimicrobial and antioxidant properties and positive impact on cells differentiation and mineralization. The pore size values of 2.8 nm confirmed the mesoporosity of the obtained bio-glasses. The biocompatibility tests on mouse fibroblast cells (NCTC clone L929) using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) activity assays revealed no cytotoxicity of Cerium containing MBGs. Formation of a hydroxycarbonate apatite (HCA) layer on MBGs surface, e.g. bioactivity of BMGs, was confirmed by XRD, FTIR, SEM and Raman Spectroscopy while presence of Ce3+/Ce4+ in the glasses before body simulated fluid (SBF) immersion was determined by XPS, UV–Vis measurements. The obtained results show that investigated MBGs are potential materials for applications in bone regeneration.

Influence of fly ash blending on hydration and physical behavior of belite–alite–ye’elimite cements

A cement powder, composed of belite, alite and ye’elimite, was blended with 0, 15 and 30 wt% of fly ash and the resulting blended cements were further characterized. During hydration, the presence of fly ash caused the partial inhibition of both AFt degradation and belite reactivity, even after 180 days. The compressive strength of the corresponding mortars increased by increasing the fly ash content (68, 73 and 82 MPa for mortars with 0, 15 and 30 wt% of fly ash, respectively, at 180 curing days), mainly due to the diminishing porosity and pore size values. Although pozzolanic reaction has not been directly proved there are indirect evidences.

3D Printing of Porous Scaffolds with Controlled Porosity and Pore Size Values.

3D printed scaffolds can be used, for example, in medical applications for simulating body tissues or for manufacturing prostheses. However, it is difficult to print porous structures of specific porosity and pore size values with fused deposition modelling (FDM) technology. The present paper provides a methodology to design porous structures to be printed. First, a model is defined with some theoretical parallel planes, which are bounded within a geometrical figure, for example a disk. Each plane has randomly distributed points on it. Then, the points are joined with lines. Finally, the lines are given a certain volume and the structure is obtained. The porosity of the structure depends on three geometrical variables: the distance between parallel layers, the number of columns on each layer and the radius of the columns. In order to obtain mathematical models to relate the variables with three responses, the porosity, the mean of pore diameter and the variance of pore diameter of the structures, design of experiments with three-level factorial analysis was used. Finally, multiobjective optimization was carried out by means of the desirability function method. In order to favour fixation of the structures by osseointegration, porosity range between 0.5 and 0.75, mean of pore size between 0.1 and 0.3 mm, and variance of pore size between 0.000 and 0.010 mm2 were selected. Results showed that the optimal solution consists of a structure with a height between layers of 0.72 mm, 3.65 points per mm2 and a radius of 0.15 mm. It was observed that, given fixed height and radius values, the three responses decrease with the number of points per surface unit. The increase of the radius of the columns implies the decrease of the porosity and of the mean of pore size. The decrease of the height between layers leads to a sharper decrease of both the porosity and the mean of pore size. In order to compare calculated and experimental values, scaffolds were printed in polylactic acid (PLA) with FDM technology. Porosity and pore size were measured with X-ray tomography. Average value of measured porosity was 0.594, while calculated porosity was 0.537. Average value of measured mean of pore size was 0.372 mm, while calculated value was 0.434 mm. Average value of variance of pore size was 0.048 mm2, higher than the calculated one of 0.008 mm2. In addition, both round and elongated pores were observed in the printed structures. The current methodology allows designing structures with different requirements for porosity and pore size. In addition, it can be applied to other responses. It will be very useful in medical applications such as the simulation of body tissues or the manufacture of prostheses.

Note on the use of different approaches to determine the pore sizes of tissue engineering scaffolds: what do we measure?

BackgroundCollagen-based scaffolds provide a promising option for the treatment of bone defects. One of the key parameters of such scaffolds consists of porosity, including pore size. However, to date, no agreement has been found with respect to the methodology for pore size evaluation. Since the determination of the exact pore size value is not possible, the comparison of the various methods applied is complicated. Hence, this study focuses on the comparison of two widely-used methods for the characterization of porosity—scanning electron microscopy (SEM) and micro-computed tomography (micro-CT).Methods7 types of collagen-based composite scaffold models were prepared by means of lyophilization and collagen cross-linking. Micro-CT analysis was performed in 3D and in 2D (pore size parameters were: major diameter, mean thickness, biggest inner circle diameter and area-equivalent circle diameter). Afterwards, pore sizes were analyzed in the same specimens by an image analysis of SEM microphotographs. The results were statistically evaluated. The comparison of the various approaches to the evaluation of pore size was based on coefficients of variance and the semi-quantitative assessment of selected qualities (e.g. the potential for direct 3D analysis, whole specimen analysis, non-destructivity).ResultsThe pore size values differed significantly with respect to the parameters applied. Median values of pore size values were ranging from 20 to 490 µm. The SEM values were approximately 3 times higher than micro-CT 3D values for each specimen. The Mean thickness was the most advantageous micro-CT 2D approach. Coefficient of variance revealed no differences among pore size parameters (except major diameter). The semi-quantitative comparison approach presented pore size parameters in descending order with regard to the advantages thereof as follows: (1) micro-CT 3D, (2) mean thickness and SEM, (3) biggest inner circle diameter, major diameter and area equivalent circle diameter.ConclusionThe results indicated that micro-CT 3D evaluation provides the most beneficial overall approach. Micro-CT 2D analysis (mean thickness) is advantageous in terms of its time efficacy. SEM is still considered as gold standard for its widespread use and high resolution. However, exact comparison of pore size analysis in scaffold materials remains a challenge.

Prediction and optimization model of activated carbon double layer capacitors based on improved heuristic approach genetic algorithm neural network

PurposeThe purpose of this paper is to study the electrochemical properties of electrode material on activated carbon double layer capacitors. It also tries to develop a prediction model to evaluate pore size value.Design/methodology/approachBack-propagation neural network (BPNN) prediction model is used to evaluate pore size value. Also, an improved heuristic approach genetic algorithm (HAGA) is used to search for the optimal relationship between process parameters and electrochemical properties.FindingsA three-layer ANN is found to be optimum with the architecture of three and six neurons in the first and second hidden layer and one neuron in output layer. The simulation results show that the optimized design model based on HAGA can get the suitable process parameters.Originality/valueHAGA BPNN is proved to be a practical and efficient way for acquiring information and providing optimal parameters about the activated carbon double layer capacitor electrode material.

Determining the Volume-size Pore Space Parameters in the Grinding Wheels

In forming structural and mechanical properties and performance criteria of a grinding wheel, pores are a key player. They are stochastically distributed in the shard of the wheel, have a random size and shape in the limited volume of the wheel shard, which makes it difficult to determine the volume-size parameters of the pore space in the grinding wheel.Experimental and analytical studies of the wheels on the ceramic bond allowed authors to reveal a porosity and pore size dependence on the size of grain, hardness, and structure of wheels, taking into account the type and the quality index of abrasives and also the method of tool modification. It was found that the tool porosity increases with increasing its structure number and decreasing hardness and size of grain.On the basis of obtained experimental data, an equation was compiled that reflects the power relationship between the porosity of a serial standard tool and its structural characteristics. By varying the structural characteristics of wheels, it is possible to determine the optimal porosity required for the grinding process in each concrete case.A comparison of experimental and calculated data on determining porosity of tools with different structural characteristics has shown that the difference in the values of porosity is within the range of 5 ÷ 8 %.Mathematical and statistical processing of experimental data, taking into account the dependence of the pore diameter on structural characteristics of the abrasive tool, allowed us to define a dependence of the pore size on the size of grain and porosity. The pore size grows with increasing size of grains and structure number and decreases with increasing hardness of the abrasive tool. The calculated pore size values differ from those experimentally obtained in the range of 5 – 12% with a confidence probability of 95 %.The presented calculation dependences and experimental data allowed authors to determine the porosity and the pore size of the tool through its GOST-normalized structural characteristics, as well as to make a rational choice of the tool for specified grinding modes and conditions.

A facile preparation of hydroxylated magnesium fluorides as an active catalyst for biodiesel production: The effect of different aging times

The MgF2−x(OH)x with various aging times (1, 3, 6 and 12 h) have been obtained from sol-gel technique. The structure, chemical bonding and porosity of material were studied by X-ray diffraction, Fourier-transform infrared spectrofotometer and N2 adsorption-desorption isotherms. The crystallinity and the number of OH groups of solids increase linearly with increasing of aging time. Moreover, the pore diameter and volume decrease from 4.79 to 2.82 nm and from 0.165 to 0.107 cm3/g, while the surface area increases from 137.84 to 150.55 m2/g with the increase in aging times, respectively. The catalytic activity of materials to yield biodiesel from Crude Palm Oil shows that the biodiesel yield decreases from 64.43 to 14.89, 12.17 and 10.49% with increasing aging times, respectively. The best performance of the catalyst depends on the greater values of pore size and volume as well as the lower crystallinity and the smaller number of OH groups.

A new method for optimal fabrication of carbon composite paper as gas diffusion layer used in proton exchange membrane of fuel cells

Carbon Papers (CPs) have been widely used as a Gas Diffusion Layer (GDL) for high performance fuel cells. Herein we report a novel method for production of GDL, without the need to carbonization and graphitization steps that is common steps in GDL production. CP is provided by a dry-laying of carbon fibers (CFs) and expanded graphite (EG) in the phenolic resin and the composites are compared with carbon paper of Toray Co., Ltd. The effect of paper thickness, aspect ratio of CF and EG value of the composite are investigated. The characterizations are performed by scanning electron microscope, maximum pore size, mean pore size, permeability, electrical conductivity, flexibility, and performance (I-V) curve. The results shown that in the optimized state of the composition in the manufactured composite, the values of mean pore size, permeability, electrical conductivity, and performance curve is reasonable and near the Toray paper, however the manufactured composite show a much higher flexibility than that of Toray paper in a qualitative test. In addition, due to removing the graphitization and carbonization steps for production of carbon paper, the produced carbon paper costs are much lower than Toray paper.

Development of an adaptive non-parametric model for estimating maximum efficiency of disc membrane

Membrane separation and filtration process are a technique of removing the impurities from the feed stream based on the pore size of the membrane bed. Permeate stream produced by the membrane are good quality due to this membrane found wide application in the field of water purification, gas-gas separation, etc. In the concerned study, the ability of the cellulose acetate disc membrane for improving the quality of the rubber industrial effluent of Tripura has been investigated in pilot scale. GMDH-multilayered feedback algorithm has been implemented to predict the maximum efficiency of the membrane. The efficiency of the membrane is maximised for the optimal value of pore size, inlet velocity, and operating pressure. It has been found that efficiency of the membrane is maximised when the pore size of the membrane is kept 2.060538 µm, inlet velocity is 0.201896 m/sec and operating pressure is 694.7201 kPa. The performance of the prepared GMDH model is evaluated by using model evaluation technique like NSE, PBIAS, slope and Y-intercept, RSR. It has been found that software predicted data can be used for trouble shooting and optimal design of the membrane bed.

Effects of chemical structure on gas transport properties of polyethersulfone polymers

Compared to polysulfone (PSF), the effects of chemical structure on gas separation performance of polyethersulfone (PES) are rarely in-depth studied. To explore the potential of various PES polymers as gas separation membranes, PES containing four different backbone structures have been synthesized. They are polyphenylsulfone (PPSU), poly trimethyl benzene ethersulfone (TPESU), polyethersulfone (PESU) and hydrophilic polyethersulfone (HPESU). Both wide-angle X-ray diffraction (XRD) and positron annihilation life-time spectroscopy (PALS) data indicate that PPSU and TPESU have bigger d-space, pore size and fractional free volume (FFV) values than PESU and HPESU. Among the four PES, PPSU stands out with the highest O2 and CO2 permeability of 1.61 and 9.13 Barrer at 35 °C, respectively, because the two additional aryl groups in PPSU contributes to high segmental motions. HPESU has the lowest gas permeability but shows the highest CO2/N2 and CO2/CH4 selectivity of 34.9 and 34.6, respectively, possibly because of the affinity between its polyethylene oxide units and CO2. The addition of trimethyl benzene groups into TPESU not only increases all gas permeability but also increases selectivity of some gas pairs. It has the highest O2/N2 selectivity of 6.0 and the 2nd highest CO2/CH4 selectivity of 33.8. Its O2 and CO2 permeability are 1.33 and 5.74 Barrer at 35 °C, respectively. In contrast, PESU has low gas permeability and average selectivity because of its linear ethersulfone chain structure. In addition, the diffusivity ratio between Henry and Langmuir modes as a function of chain structure has been investigated. The diffusivity ratio is always smaller than 32%. This study may provide useful insights to design better PES polymers for gas separation.

Subsurface Flow and Moisture Dynamics in Response to Swash Motions: Effects of Beach Hydraulic Conductivity and Capillarity

AbstractA combined field and numerical study was conducted to investigate dynamics of subsurface flow and moisture response to waves in the swash zone of a sandy beach located on Cape Henlopen, DE. A density‐dependent variably saturated flow model MARUN was used to simulate subsurface flow beneath the swash zone. Values of hydraulic conductivity (K) and characteristic pore size (α, a capillary fringe property) were varied to evaluate their effects on subsurface flow and moisture dynamics in response to swash motions in beach aquifers. The site‐specific modeling results were validated against spatiotemporal measurements of moisture and pore pressure in the beach. Sensitivity analyses indicated that the hydraulic conductivity and capillary fringe thickness of the beach greatly influenced groundwater flow pathways and associated transit times in the swash zone. A higher value of K enhanced swash‐induced seawater infiltration into the beach, thereby resulting in a faster expansion of a wedge of high moisture content induced by swash cycles, and a flatter water table mound beneath the swash zone. In contrast, a thicker capillary fringe retained higher moisture content near the beach surface, and thus, significantly reduced the available pore space for infiltration of seawater. This attenuated wave effects on pore water flow in the unsaturated zone of the beach. Also, a thicker capillary fringe enhanced horizontal flow driven by the larger‐scale hydraulic gradient caused by tides.

Green synthesis of degradable conductive thermosensitive oligopyrrole/chitosan hydrogel intended for cartilage tissue engineering

Electroactive scaffolds containing conductive polymers can promote tissue repair and regeneration. However, these polymers are non-degradable and cannot be removed from body. To overcome this limitation of conductive polymers, we developed a novel injectable electroactive hydrogel containing pyrrole oligomers which possessed the unique properties of being both electrically conductive and biodegradable. First, pyrrole oligomers were synthesized via chemical polymerization and were found to be amorphous with a non-globular morphology. Then, three different compositions of injectable chitosan/beta glycerophosphate hydrogels containing different concentrations of pyrrole oligomers were synthesized and characterized for chemical structure, morphology, conductivity, swelling ratio, In vitro biodegradation and gelation time. An increase in oligopyrrole content resulted in decreased pore size, and increased gelation time, swelling ratio, conductivity and degradation time. Among all the hydrogel compositions, the sample with pyrrole oligomer:chitosan ratio of 0.1 (w/w) showed the most prominent biodegradability, biocompatibility, electro-activity, swelling ratio and pore size values and was chosen as the optimal electroactive hydrogel composition in this work.

Acid-catalyzed hydrolysis of semi-aromatic polyamide NF membrane and its application to water softening and antibiotics enrichment

The effect of post-treatment by acid-catalyzed hydrolysis of a commercial NE70 semi-aromatic polyamide (PA) membrane was systemically investigated to determine feasibility of use in water softening and antibiotic enrichment applications. The surface of a post-treated PA membrane was characterized using various analytical tools: SEM (Scanning Electron Microscopy) for surface morphology, ATR-FTIR (Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy) for chemical bonds, contact angle for hydrophilicity of membrane surface, and electrophoretic light scattering spectrophotometer for surface charge of membrane surface. Conversion of amide groups to amine and carboxyl groups by post-treatment increased hydrophilicity and absolute value of surface charge as well as pore size and molecular weight cut off (MWCO) value. Post-treated membrane under optimal condition showed enhancement of water flux (∼10%) as well as ∼20% ideal selectivity (Na+/Mg2+) for water softening using a single electrolyte solution. In addition, mixture selectivity (Na+/Mg2+) using a mixture solution at pH 3 was also improved ∼2.6 times. Post-treated membranes at pH 0.25 for 7 and 14days as optimization points were also applied to enrichment of antibiotics which are erythromycin (ERY) and vancomycin (Van). Optimized post-treatment membranes showed higher water flux and lower NaCl rejection as well as competitive rejection of antibiotics when compared to virgin NE70 membrane or other commercial/fabricated membranes. The approach to post-treatment of semi-aromatic membrane by the acid-catalyzed hydrolysis method can be utilized as a multipurpose usage in the future depending on characteristics of the target compound (e.g. surface charge (positive/negative) or size diversity).

Special wettable nanostructured copper mesh achieved by a facile hot water treatment process

In this research, a special wettable copper mesh with superhydrophobicity and superoleophilicity properties is reported using a low-cost, eco-friendly, rapid, and scalable synthesis method. Hot water treatment (HWT) method is used to integrate the micro-textured copper mesh surface with a nanoscale roughness to achieve a hierarchical micro-nano structured surface. The surface energy of the nanoscale roughened copper mesh reduced by coating the hot water treated mesh with polymer ligands containing thiol or fluorine functional groups of low energy. Surface morphology characterization showed the formation of copper oxide nanostructures on the mesh surface by hot water process performed at 95 °C and under a low dissolved oxygen condition. X-ray diffraction patterns reveal the development of stable, uniformly distributed, and compactly arranged, cubic and plate-like nanostructures of cuprous oxide (Cu2O) on the copper mesh surface. The surface wettability of the as-prepared copper mesh was assessed by contact angle (CA) measurement for water and several oils and organic solvents. CA values showed the formation of special wettable copper mesh surface with superhydrophobic property with water contact angle of about 157° and superoleophilic property with oil contact angle as low as 0°. In addition, the effect of the mesh’s geometry on the wetting property was examined through correlations between wire diameter, pore size, and optimal values for the highest water CA.

Synthesis and Pore Structure Characterisation of Novel Mesoporous MgO-CeO<sub>2</sub>/SBA-15 as a Potential Catalyst Support

The high interest in the synthesis of mesoporous catalyst demands that novel materials are developed with simple methods capable of improving process yields. In this work, a novel heterogeneous mesoporous catalyst support has been synthesized using mesoporous SBA-15 loaded with mixed bimetal oxides of CeO2 and MgO. Formation of the SBA-15 was actuated in air at room temperature (25°C) and in oven conditions at 100°C after which cerium nitrate and magnesium nitrate precursors were then impregnated into the SBA-15 framework and calcined at 550°C for each of the air and oven crystallization processes. XRD peak patterns confirmed SBA-15 formation and dispersion of nanocrystallites of CeO2 and MgO within the porous framework of SBA-15. Both the air and oven dried processes produced mesoporous MgO-CeO2/SBA-15 catalysts with isotherms that exhibit typical H1 type hysteresis confirming that they possess open-ended cylindrical mesopores. The structural data extracted gave average pore size, pore volume and surface area values in the ranges of 3-5.2 nm, 0.600-2.500 cc/g and 400-500 m2/g respectively which is ideal for several industrial applications.

Chloramphenicol-based poly(ester-ether)urethane bioconjugates with antibacterial properties for biomedical applications

New chloramphenicol-based poly(ester-ether)urethane bioconjugates intended for biomedical applications are presented. Structure–property relationship in the tested biomaterials is established by cross-inspection of the ATR-FTIR investigation, DSC analysis, thermogravimetric analysis, surface morphology characterization, water sorption and/or desorption properties, and antimicrobial efficiency of the obtained polyurethane biomembranes. The estimated values of activation energy for thermal degradation under nitrogen fall between those found for poly(ether urethane)s and poly(ester urethane)s. SEM microphotographs show that the resulted morphologies of polyurethanes are different due to the diverse polyether segments which determine the supramolecular architecture of the self-assembled films. The estimated moisture diffusion coefficients, sorption capacity are dependent on polyurethane network microstructure. The monolayer sorption and average pore size values were estimated by applying BET model. The values of BET area and monolayer capacity are correlated with antibacterial activities. The synthesized biocidal polyurethanes bearing covalently attached chloramphenicol are effective at inactivation of tested bacteria: Sarcina lutea and Escherichia coli.