Search results for "Polymers."
showing 10 items of 3543 documents
Evolution of the “knitting pattern” morphology in ABC triblock copolymers
1996
A new morphology of ternary ABC triblock copolymers is presented which results from the asymmetric interaction between a centre block (poly(ethylene-co-butene)) to different end blocks (polystyrene and poly(methyl methacrylate)). This morphology with the appearance of a “knitting pattern” can be described as an intermediate of a morphology of A, B and C lamellae and a morphology of A and C lamellae with B cylinders at the A/C interface.
Thermal frontal polymerization with a thermally released redox catalyst
2012
ABSTRACT: We studied thermal frontal polymerization using a re-dox systeminan attempt to lower the temperature of thefrontallypolymerizable system while increasing the front velocity so as toobtain a self-sustaining front in a thinner layer than without theredox components. A cobalt-containing polymer with a meltingpoint of 63 C (Intelimer 6050X11) and cumene hydroperoxidewere used with a triacrylate. The use of the Intelimer decreasedthe front velocity but allowed fronts to propagate in thinner layersand with more filler while still having a pot life of days. Nonplanarmodes of propagation occurred. Fronts propagated faster when6-O-palmitoyl- L -ascorbic acid was used as a reductant. Intere…
Phase Behavior of Active Swimmers in Depletants: Molecular Dynamics and Integral Equation Theory
2013
We study the structure and phase behavior of a binary mixture where one of the components is self-propelling in nature. The inter-particle interactions in the system were taken from the Asakura-Oosawa model, for colloid-polymer mixtures, for which the phase diagram is known. In the current model version the colloid particles were made active using the Vicsek model for self-propelling particles. The resultant active system was studied by molecular dynamics methods and integral equation theory. Both methods produce results consistent with each other and demonstrate that the Vicsek model based activity facilitates phase separation, thus broadening the coexistence region.
Solubility and solvation features of native cyclodextrins in 1-ethyl-3-methylimidazolium acetate
2022
The comprehension of the mechanism entailing efficient solvation of cyclodextrins (CD) by green solvents is of great relevance to boost environmentally sustainable usages of smart supramolecular systems. Here, 1-ethyl-3- methylimidazolium acetate, an ecofriendly ionic liquid (IL), is considered as an excellent solvent for native CDs. This IL efficiently dissolves up to 40 wt.% β- and γ-CD already at ambient temperature and X-ray scattering indicates that CDs do not tend to detrimental flocculation under these drastic concentration conditions. Simu- lation techniques reveal the intimate mechanism of CD solvation by the ionic species: while the strong hydrogen bonding acceptor acetate anion i…
Inhalable Formulation Based on Lipid–Polymer Hybrid Nanoparticles for the Macrophage Targeted Delivery of Roflumilast
2022
Here, novel lipid-polymer hybrid nanoparticles (LPHNPs), targeted to lung macrophages, were realized as potential carriers for Roflumilast administration in the management of chronic obstructive pulmonary disease (COPD). To achieve this, Roflumilast-loaded fluorescent polymeric nanoparticles, based on a polyaspartamide-polycaprolactone graft copolymer, and lipid vesicles, made from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1,2-distearoyl-sn-glycero-phosphoethanolamine-N-(polyethylene glycol)-mannose, were properly combined using a two-step method, successfully obtaining Roflumilast-loaded hybrid fluorescent nanoparticles (Man-LPHFNPs@Roflumilast). These exhibit colloidal size and a ne…
Enhanced plasmonic processes in amino-rich plasma polymer films for applications at the biointerface
2021
A new plasmonic biosensor was developed in a planar chip-based format by coupling the plasmonic properties of gold nanoparticles (Au NPs) with the mechanical and bioadhesive features of unconventional organic thin films deposited from plasma, namely primary amine-based plasma polymer films (PPFs). A self-assembled layer of spherical Au NPs, 12 nm in diameter, was electrostatically immobilized onto optically transparent silanised glass. In the next step, the Au NP layer was coated with an 18 nm polymeric thick PPF layerviathe simultaneous polymerization/deposition of a cyclopropylamine (CPA) precursor performed by radio frequency discharge, both in pulsed and in continuous wave modes. The CP…
Ubiquitin and ubiquitination in cells from the marine sponge Geodia cydonium.
1994
Marine sponges, e.g. Geodia cydonium, have been intensively used to investigate the biochemical and molecular biological basis of cell-cell- and cell-matrix adhesion. It has been shown that a family of galactose-specific lectins, which are present in the extracellular space of G. cydonium, is a main component involved in cell-matrix adhesion in the sponge system. In the present study it is outlined that the purified 16-kDa lectin-1 binds to a 67-kDa membrane-associated protein. This lectin-binding protein undergoes mono- and diubiquitination after incubation of dissociated sponge cells with the homologous aggregation factor (AF), a molecule involved in cell-cell adhesion. The gene coding fo…
Acquisition of Structure-guiding and Structure-forming Properties during Maturation from the Pro-silicatein to the Silicatein Form
2012
Silicateins are the key enzymes involved in the enzymatic polycondensation of the inorganic scaffold of the skeletal elements of the siliceous sponges, the spicules. The gene encoding pro-silicatein is inserted into the pCold TF vector, comprising the gene for the bacterial trigger factor. This hybrid gene is expressed in Escherichia coli and the synthesized fusion protein is purified. The fusion protein is split into the single proteins with thrombin by cleavage of the linker sequence present between the two proteins. At 23 °C, the 87 kDa trigger factor-pro-silicatein fusion protein is cleaved to the 51 kDa trigger factor and the 35 kDa pro-silicatein. The cleavage process proceeds and res…
Polymetallic oxalate-based 2D magnets: Soluble molecular precursors for the nanostructuration of magnetic oxides
2010
Here we describe the synthesis and magnetic characterization of a family of 2D polymetallic oxalate-bridged polymeric networks with general formula [M(II)(H(2)O)(2)](3)[M(III)(ox)(3)](2)(18-crown-6)(2) (M(III) = Cr, Fe; M(II) = Mn, Fe, Co, Ni; 18-crown-6 = C(12)H(24)O(6)). Depending on the nature of the trivalent metal ion, they exhibit ferro- (Cr(3+)) or ferrimagnetic (Fe(3+)) ordering in the 3.6-20 K interval. In contrast with most of the oxalate-bridged CPs reported so far, these complexes do not need any additional templating cation for their assembly and represent the first series of oxalate-based polymeric networks which can be considered intrinsically neutral. As previously observed …
Thermal analysis applied to the characterization of degradation in soil of polylactide: I. Calorimetric and viscoelastic analyses
2010
[EN] An accelerated soil burial test has been performed on a commercial polylactide (PLA) for simulating non-controlled disposal. Degradation in soil promotes physical and chemical changes in polylactide properties, which can be characterized by Thermal Analysis techniques. Physical changes occurred in polylactide due to the degradation in soil were evaluated by correlating their calorimetric and visco-elastic properties. It is highly remarkable that each calorimetric scan offers specific and enlightening information. Degradation in soil affects the polylactide chains reorganization. A multimodal melting behavior is observed for buried PLA, degradation in soil also promotes the enlarging th…