Colloid and Polymer Science

UNLABELLED: The AC electrical properties of EVA- and NBR-based composites filled with different conductive fillers were investigated. Result shows several magnitudes of increment in AC electrical conductivity and dielectric permittivity after the addition of these conductive fillers, indicating that these materials can be used as supercapacitors. The magnitude of increment was varied according to polymer and filler types. Herein, we also have tested the applicability of different sigmoidal models to find out the percolation threshold value of permittivity for these binary polymer composite systems...

Cinnamon essential oil (CNO) is a natural and renewable antibacterial agent. However, CNO is highly volatile and unstable, which limits its practical application as a long-term and wide antibacterial agent. In order to improve the CNO stability, we have microencapsulated CNO into composite microcapsules basing on Pickering emulsion stabilized by silica (SiO2 ) nanoparticles. The CNO-loaded composite microcapsules possess the hybrid microcapsule shell including SiO2 , xanthan gum and chitosan. Moreover, the results show that the microcapsules have spherical appearance...

One of the emerging technologies of the recent times harboring nanotechnology to fabricate nanofibers for various biomedical and environmental applications are electrospinning (nanofiber technology). Their relative ease in use, simplicity, functionality and diversity has surpassed the pitfalls encountered with the conventional method of generating fibers. This review aims to provide an overview of electrospinning, principle, methods, feed materials, and applications toward tissue engineering. To begin with, evolution of electrospinning and its typical apparatus have been briefed...

Sugar chain immobilized polymer particles having both magnetic and fluorescent properties can be expected to be useful in a wide variety of biomedical applications such as the detection, separation, and purification of proteins, viruses, or bacteria, because sugar chains specifically adsorb them. Since high magnetic responsiveness is required for such applications, we attempted to fabricate core-shell particles consisting of a submicron-sized magnetic core and a thin polymer shell (nano- to dozens of nanometers thick) that incorporates a fluorescent dye, with sugar molecules immobilized on the surface...

Several difunctional oligomers were synthesized by functionalizing perfluoropolyalkylether (PFPAE) chains with different vinyl ethers and epoxides end-groups. Due to their innate synthetic challenges and demanding purification protocols, the PFPAE derivatives were obtained in low yield and with an average functionality lower than 2. However, the functionalized PFPAE oligomers were successful in being used in photo-induced cationic polymerization processes, obtaining transparent and soft films. The influences of the fluorinated chains, and various end-groups on the photopolymerization process were investigated, as well their chemical stability, thermal degradation, and surface properties...

New perfluoropolyalkylether (PFPAE) monomers, chain extended with different alkyl groups and functionalized with vinyl ether or epoxide end-groups, were employed, together with trimethylolpropane trivinyl ether or trimethylolpropane triglycidyl ether, to produce fluorinated copolymers. The photoinduced cationic polymerization was investigated, and the PFPAE-based copolymer properties were thoroughly characterized. Interesting surface properties and two different values of refractive index were observed: thus, these fluorinated copolymers can be suitable materials for the manufacture of self-cleaning coatings and optical waveguides...

Poly( N -isopropylacrylamide) microgels prepared without exogenous crosslinker are extremely "soft" as a result of their very low crosslinking density, with network connectivity arising only from the self-crosslinking of pNIPAm chains. As a result of this extreme softness, our group and others have taken interest in using these materials in a variety of bioengineering applications, while also pursuing studies of their fundamental properties. Here, we report deswelling triggered structural changes in poly ( N -isopropylacrylamide- co -acrylic acid) (ULC10AAc) microgels prepared by precipitation polymerization...

To explore block glycopolymers as novel polymeric delivery nanocarriers for anticancer drug bortezomib (BTZ), three types of block glycopolymers, poly(ethylene glycol)- block -poly(gluconamido ethyl methacrylate) (PEG113 - b -PGAMA20 ), poly(ethylene glycol)- block -poly(styrene)- block -poly(gluconamido ethyl methacrylate) (PEG113 - b -PS50 - b -PGAMA20 ), and poly(ethylene glycol)- block -poly(2-(diethyl amino) ethyl methacrylate)- block -poly(gluconamido ethyl methacrylate) (PEG113 - b -PDEA50 - b -PGAMA20 ), were synthesized via atom transfer radical polymerization (ATRP) using a PEG-based ATRP macroinitiator...

Pyrazole-3,4-dicarboxylic acid 2 was synthesized via the hydrolysis of pyrazole-3-carboxylic acid 1 and subsequently heated with thionyl chloride to give the novel pyrazole-3,4-dicarbonyl dichloride 3 , which was easily converted into oligo-pyrazole 4 upon its reaction with p -phenylene-diamine. These newly synthesized compounds were characterized by 1 H-NMR, 13 C-NMR, and FT-IR spectroscopy, and gel permission chromatography (GPC). Three novel oligo-pyrazole thin films were prepared using oligo-pyrazole 4 with these respective values of thickness: 20, 21, and 24 μm...

The Surface-enhanced Raman spectroscopy is the essential tool for various levels of the molecular studies. In order to become widely used as a fast analytical tool, the enhancing structures such as the nanoparticles have to be simple, inexpensive, and offer good flexibility in enhancing properties and the spectral range. In this paper, we investigated the plasmonic properties of the metal nanoparticles, to which the molecules of interest can be adsorbed, forming the bionanocomplexes. Here, for the first time, we provided the collection of the results gathered in one article, which can serve as the basis or guidance for designing the SERS studies on different bionanocomplexes, various nanoparticle structures, sizes, and excitation wavelengths...

The thermal and rheological properties of suspensions of microencapsulated phase change materials (MPCM) in glycerol were investigated. When the microcapsule concentration is raised, the heat storage capacity of the suspensions becomes higher and a slight decline in the thermal conductivity of the suspensions is observed. The temperature-dependent shear-thinning behaviour of the suspensions was found to be strongly affected by non-encapsulated phase change materials (PCM). Accordingly, the rheological properties of the MPCM suspensions could be described by the Cross model below the PCM melting point while a power law model best described the data above the PCM melting point...

The efficacy of inhaled antibiotics is often impaired by insufficient drug penetration into plugged and poorly ventilated airways. Liquid ventilation with perfluorocarbon (PFC) containing emulsified aqueous antibiotics, or antibacterial perfluorocarbon ventilation, could potentially improve treatment of respiratory infections when used as an adjunct therapy to inhaled antibiotics. The molecular structure and concentration of the fluorosurfactant used to stabilize such water-in-PFC emulsions will have significant effects on the efficacy and safety of the resulting treatment...

We present a generic and versatile low temperature route to produce macro-porous bodies with porosity and pore size distribution that are adjustable in a wide range. Capillary suspensions, where the minor fluid is a monomer, are used as pre-cursors. The monomer is preferentially located between the particles, creating capillary bridges, resulting in a strong, percolating network. Thermally induced polymerization of these bridges at temperatures below 100 °C for less than 5 hours and subsequent removal of the bulk fluid yields macroscopic, self-supporting solid bodies with high porosity...

Fluorinated spheres with grafted poly(ethylene glycol) (PEG) have been synthesized using a semi-batch emulsion polymerization in which the initiator is fed slowly to the reaction. In this way, PEG-grafted colloidal spheres can be fabricated with varying PEG chain length, different cores and varying degrees of crosslinking. The resulting batches have been characterized using disc centrifuge photosedimentometry and small-angle X-ray scattering. The size distribution is shown to be a sensitive function of the molar ratio of the reactive PEG macromonomer to fluorinated monomer, and with some optimization latices of very low polydispersity can be obtained with this simple synthesis method...

The objective of this study is to discover a synergistic effect between foam stability in bulk and micro-emulsion phase behaviour to design a high-performance chemical system for an optimized alkaline-surfactant-foam (ASF) flooding for enhanced oil recovery (EOR). The focus is on the interaction of ASF chemical agents with oil in the presence and absence of a naphthenic acid component and in situ soap generation under bulk conditions. To do so, the impact of alkalinity, salinity, interfacial tension (IFT) reduction and in situ soap generation was systematically studied by a comprehensive measurement of (1) micro-emulsion phase behaviour using a glass tube test method, (2) interfacial tension and (3) foam stability analysis...

The assumption that during emulsion polymerization, the monomer molecules simply diffuse through the aqueous phase into the latex particles is a commonplace. However, there are experimental hints that this might not be that easy. Here, simulation results are discussed based on Fick's diffusion laws regarding the swelling of latex particles. The results of quantitative application of these laws for swelling of latex particles allow the conclusion that the instantaneous replenishment of the consumed monomer during emulsion polymerization requires a close contact between the monomer and the polymer particles...

The thermal responsive behavior of adsorbed layers of diblock copolymers of poly(N-isopropylacrylamide) (PNIPAAM) and poly((3-acrylamidopropyl)trimethylammonium chloride) (PAMPTMA(+)) with γ-cyclodextrin (γ-CD) at the solid/liquid interface has been investigated using three in situ techniques: null ellipsometry, quartz-crystal microbalance with dissipation monitoring, and neutron reflectometry. The measurements provided information about the adsorbed amounts, the layer thickness, hydration and viscoelastic properties, and the interfacial structure and composition...

The adsorption of polyvinylpyrrolidone (PVP) by the thermoregulating microcapsules has been studied. The mass ratio of PVP has been changed from 1 to 20, with respect to the lowest amount of PVP value (4.08 g). The results confirmed that a large amount of PVP was adsorbed by the polymeric shell. Experimental data were perfectly fitted by Langmuir model, obtaining at a confidence level of 95% values of 192.9 ± 0.4 g/kg and 0.18 ± 0.11 m(3)/kg for the maximum adsorption capacity and the equilibrium constant, respectively...

Non-aqueous microgel particles are commonly synthesised in water, dried, and then redispersed in non-aqueous solvents. An important factor to consider when synthesising such particles is the initiator, which can determine how well the particles disperse in solvents. Polystyrene microgel particles were made with three different initiators. When a neutral, oil soluble initiator (azobisisobutyronitrile) was used the particles dispersed in toluene as well as cyclohexane and decalin. In contrast, anionic, water-soluble initiators (potassium persulfate or azobis(4-cyanovaleric acid)) created particles that only redispersed in toluene and not the other two solvents...

This mini review is focused on the emerging nexus between the medical device and pharmaceutical industries toward the treatment of damaged articular cartilage. The physical rationale of hyaluronic acid and phospholipid preparations as tribological surgical adjuvants for repaired articular cartilage surfaces is explored, with directions for possible new research which have arisen due to the therapeutic advance of the physiochemical scalpel. Because synovial joint lubrication regimes become dysfunctional at articular cartilage lesion sites as a result of the regional absence of the surface active phospholipid layer and its inability to reform without surgical repair, hyaluronic acid and phospholipid intra-articular injections have yielded inconsistent efficacy outcomes and only short-term therapeutic benefits mostly due to non-tribological effects...