Non-modified Poly Research Articles

Tunable double-stranded inclusion complexes of γ-cyclodextrin threaded onto non-modified poly(ethylene glycol)

The formation of double-stranded inclusion complexes (ICs) between γ-cyclodextrin (γ-CD) and non-modified poly(ethylene glycol) (PEG) was reported to be of trace yield, while in the present work, tunable inclusion complexes between γ-CD and non-modified PEG were successfully prepared by choosing suitable γ-CD concentrations and PEG molecular weights. The obtained γ-CD/PEG ICs showed double-stranded structure whose yield, appearance, and forming rate were significantly affected by PEG molecular weight and temperature as revealed by means of optical microscopy, XRD, DSC, 1H NMR, and ITC. This improved understanding on how to control the formation of double-stranded inclusion complexes should be very helpful for preparation of more sophisticated molecular machines.

Towards integrated anti-microbial capabilities: Novel bio-fouling resistant membranes by high velocity embedment of silver particles

Biofilm formation on membranes during water desalination operation and pre-treatments limits performance and causes premature membrane degradation. Here, we apply a novel surface modification technique to incorporate anti-microbial metal particles into the outer layer of four types of commercial polymeric membranes by cold spray. The particles are anchored on the membrane surface by partial embedment within the polymer matrix. Although clear differences in particle surface loadings and response to the cold spray were shown by SEM, the hybrid micro-filtration and ultra-filtration membranes were found to exhibit excellent anti-bacterial properties. Poly(sulfone) ultra-filtration membranes were used as for cross-flow filtration of Escherichia coli bacteria solutions to investigate the impact of the cold spray on the material׳s integrity. The membranes were characterized by SEM–EDS, FT-IR and TGA and challenged in filtration tests. No bacteria passed through the membrane and filtrate water quality was good, indicating the membranes remained intact. No intact bacteria were found on hybrid membranes, loaded with up to 15wt% silver, indicating the treatment was lysing bacteria on contact. However, permeation of the hybrid membranes was found to be reduced compared to control non-modified poly(sulfone) membranes due to the presence of the particles across the membrane material. The implementation of cold spray technology for the modification of commercial membrane products could lead to significant operational savings in the field of desalination and water pre-treatments.

In Vitro Haemocompatibility Evaluation of PET Surfaces Using the Quartz Crystal Microbalance Technique

Owing to the complex influences of several experimental conditions on the in vitro alteration of blood, there is still a lack of viable in vitro tests and methods for blood compatibility evaluation of biomaterials. The aim of this research was to study a new approach for the haemocompatibility assessment of differently modified PET surfaces using the quartz crystal microbalance with dissipation unit (QCM-D) technique and measure the mass increase caused by clot formation under physiological conditions. For this purpose some of the most frequently applied in vitro methods for haemocompatibility determination, i.e., clotting time measurement and observation of red blood cells' mobility, were applied and their accuracy and sensitivity compared to the new QCM-D approach. Haemocompatibility was evaluated for non-modified poly(ethylene terephthalate) (PET) surfaces and PET surfaces coated with dextran sulphate and heparin. The basic anti-coagulant properties of heparin and dextran sulphate were analysed by means of their activated partial thromboplastine time (APTT). PET, as well as different polysaccharides coatings were chosen for this study due to their promising biocompatible properties and numerous possibilities for biomedical applications. The results showed that the new QCM-D technique to study clot formation in contact with PET surfaces under physiological environment was the most informative and accurate for in vitro haemocompatibility assessment. Although the results achieved with the other two methods were in good correlation, they did not provide such a high level of sensitivity.

Preparation of Poly(vinylidene fluoride-co-trifluoroethylene) Film with a Hydrophilic Surface by Direct Surface-initiated Atom Transfer Radical Polymerization without Pretreatment

Abstract Surface-initiated atom transfer radical polymerization (ATRP) of tert-butyl acrylate was carried out directly from a nonmodified poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-co-TrFE)] film surface to give a polymer brush, which was further converted to a poly(acrylic acid sodium salt) brush by hydrolysis. A hydrophilic surface was successfully created at the outermost surface of P(VDF-co-TrFE) film without any change in the bulk physical properties. Also the effect of surface nanotexture formation on wettability was investigated.

Influence of Fibre and Matrix Modifications on Mechanical and Physical Properties of Flax Fibre Reinforced Poly(propylene)

In this work several types of flax were used as reinforcement in poly(propylene) based unidirectional composites. These flax types included non-treated as well as treated (boiled) samples. On the other hand, two types of poly(propylene) were used as matrix: non-modified poly(propylene) (PP), and maleic anhydride modified poly(propylene) (MAAP-PP). The influence of both fibre and matrix modification was studied through mechanical (flexural) and physical (density, sorption, and drying) tests. Combination of boiled flax with MAAP-PP proved to yield the best mechanical properties, combined with good physical properties. A 100% stress transfer between fibre and matrix could be calculated in this optimised case. Interlaminar shear strentgh tests were done in order to confirm this improved fibre-matrix adhesion.

Oscillation of Membrane Potential in Immobilized DNA Membranes

Immobilized DNA membranes prepared by binding between DNA and poly(γ-methyl-l-glutamate) membranes having a cis-diaminedichloro platinum group-generated oscillation of the membrane potential under a concentration gradient of several salts at frequencies between 0 and 5 Hertz at pH 7.0, although nonmodified poly(γ-methyl-l-glutamate) membranes showed a constant potential. The amplitude of oscillation depended on the length of the joint segments between the DNA and poly(γ-methyl-l-glutamate) membranes; the immobilized DNA membranes modified with diaminopropane and diaminobutane showed a high oscillation amplitude (e.g., 4−5 mV). It was also influenced by the salts used, and the highest oscillation amplitude in the membrane potential across the immobilized DNA membranes modified with diaminobutane was observed when NaCl was used as the salt solution. Fast Fourier transport analysis revealed that the oscillation of the membrane potential had several specific frequencies depending on the salt solution and the ...

Water Self-Diffusion in Aqueous Associative Polymer Solutions

Water self-diffusion in aqueous model associative polymer (AP) solutions, hydrophobically end-capped poly(ethylene oxide), C12EO200C12 (AP9,) and C12EO90C12 (AP4), has been studied with the NMR-PGSE method and compared to the diffusion in nonmodified poly(ethylene oxide) PEO. It was found that it decreases monotonically with increasing polymer concentration, giving Di/D0 ≈ 0.2 at 50 wt % (D0 being the water self-diffusion coefficient in the absence of polymer), independently of polymer molecular weight and modification. In further evaluation of the data, the cell-diffusion model was used. Such an analysis suggests that up to a polymer content of about 2 wt % AP9, water diffusion is not significantly affected by the polymer. Above this concentration, up to about 10 water molecules per EO group are affected in AP9 and AP4 solutions. On increasing the temperature, water self-diffusion increases, following an Arrhenius-like equation, with Ea equal to that of pure water at low polymer content (10 wt %). The ac...