The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
We have investigated the validity of the popular assumption of identical linear spring (ILS) in polymer-colloids aggregated clusters. The ILS assumption suggests that all inter-particle bonds in an aggregated cluster of polymer chains and colloid particles can be represented by identical linear springs. The assumption has been challenged by several experiments that showed the bond stiffness varies...
In this study, the crystalline morphology and mechanical property of Olefin Block Copolymer (OBC) were tailored by adding a small amount (up to 10 wt%) of ultrahigh molecular weight polyethylene (UHMWPE). To do this, OBC and UHMWPE was solution blended first and then subjected to compression molding or injection molding, respectively. It was found that a small quantity of UHMWPE (0.5 wt%, 1 wt%) can...
In this work, extremely high molecular weight (Mw) poly(allylamine hydrochloride) (PAH, 900K g/mol) and poly(acrylic acid) (PAA, 225 K g/mol) were selected to amplify the difference in the growth of multilayers in comparison with low Mw PAA (15K g/mol) and PAH (15K g/mol). By varying the pH conditions, the PAH/PAA multilayers were fabricated via the layer-by-layer (LbL) assembly in both linear and...
A series of new urethane methacrylate (UMA) monomers were synthesized with the reaction of ethylene carbonate and aliphatic amines, followed by the reaction with methacrylic anhydride. The monomers were characterized by 1H, 13C nuclear magnetic resonance (NMR), mass (MS), and Fourier transform infrared (FTIR) spectroscopies. Urethane latexes were prepared by monomer-starved semibatch polymerization...
The present work consisted in the in situ polymerization of a liquid monomer (styrene) into a melt polymer matrix (PMMA) as an innovative method to prepare polymer blends at fine dispersions. That was possible by using an original mixing/reactor device called RMX®, which significantly develops extensional flow, greatly enhancing the mixing efficiency. Resultant morphology was characterized by TEM...
Remarkable improvement in mechanical properties of acrylonitrile butadiene rubber (NBR) composites is achieved by incorporating nano-titania that is synthesised in solution of the raw rubber using titanium n-butoxide (TNB) as the titania precursor. This is achieved by designed and controlled incorporation of titania that resulted in very good dispersion of titania of nanometric dimension in rubber...
The focus of this work was on the significant changes in the water dynamics of aqueous poly (N-isopropylacrylamide) (PNIPAM) solution during sol-to-gel transition. Through the use of NMR (particularly two-dimensional 2H NMR T1-T2 relaxation) and rheology, we were able to show that below 34° C fast exchange occurs among free water and water molecules adsorbed on the surface of PNIPAM molecules. At...
A novel benzoxazine-containing temperature T-sensitive fluorescent polyfluorenes (BluePF-BZ) had been prepared. A benzoxazine monomer (BHPF-paa) was firstly synthesized with 9,9-Bis(4-hydroxyphenyl)fluorene, propargylamine and paraformaldehyde through Mannich condensation reaction. The as-prepared BHPF-paa was then incorporated into the preparation of polyfluorenes, and the main-chain BluePF-BZ could...
We report a new methacrylate copolymer having pendant furfuryl groups (PFu) reactive to maleimide-bearing compounds to form thermally-induced crosslinked networks exhibiting self-healability through thermoreversible Diels-Alder (DA)/Retro-DA reactions. The PFu is synthesized by a combination of a facile radical polymerization with post-modification methods through a base-catalyzed coupling reaction...
We carried out molecular dynamics simulations to study the crystallization of polymer melts subjected to confinement between two parallel walls. Two types of walls, bare and grafted walls, are studied. The bare walls are slippery for chain motions, and the interactions between polymer chains and the walls are moreover chosen either attractive or repulsive. The crystallization in the case of bare walls...
Polytetrafluoroethylene (PTFE) has some unique properties such as high hydrophobicity and high resistance to elevated temperatures, chemicals and solvents which make it of interest for fibres and textiles. However, PTFE normally decomposes before melting, meaning that it cannot be readily melt-spun into fibres. In addition, PTFE is insoluble in all common organic solvents, prohibiting its use in common...
Effect of degree of sulfonation on dynamic mechanical properties, dehydration rate, crystallinity, thermal stability and other fuel cell properties (e.g. proton conductivity, ion exchange capacity, water uptake capacity, etc.) of SPEEK membrane are studied and correlated with microstructure. With increasing degree of sulfonation (DS), α-relaxation peak shifts from 135 to 166 °C, while β-relaxation...
The thermal imidization process of 1,2,4,5-benzenetetracaboxylic (PMDA)/4,4’-diamnodiphenyl ether (4,4′-ODA) solutions in N-methyl-2-pyrrolidone (NMP) from polyimide (PI) precursor, poly (amic acid) (PAA), was systematically investigated through a series of characterization methods, such as Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry...
Surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization has been widely used to synthesize various polymers grafted from nanoparticles (NPs) for incorporation into polymer nanocomposites. It is believed that these grafted polymer brushes, with a similar chemistry as the matrix polymer, can be employed to improve NP dispersion by reducing unfavorable interactions...
This study demonstrates the feasibility of printing 3D composite objects based on acrylic photocurable formulations containing CNTs, by using an unmodified commercial DLP-printer. In the preliminary investigations, the most suitable formulation was developed. Viscosity and dispersion stability were adjusted by the addition of a reactive diluent to the acrylic formulation. FT-IR analyses in real time...
Shape memory polymers (SMPs) have been intensively studied for a wide range of potential applications, including biomedical devices, morphing structures, and 4D printing. For amorphous polymers, the glass transition temperature measured by dynamic mechanical analysis (DMA) is an important consideration in designing SMPs. However, typical DMA curves are cooling- and heating-rate dependent and the cooling...
Taking advantage of versatile o-nitrobenzyl chemistry, the present study highlights the design of photocurable epoxy networks that undergo spatially controlled bond cleavage in response to UV irradiation. The synthetic strategy involves the preparation of epoxy monomers with photolabile o-nitrobenzyl ester (o-NBE) links that are cured via photoinduced cationic ring opening reaction. Two different...
We demonstrate in this paper how polymerization induced self-assembly (PISA) using RAFT can be used to synthesize very asymmetric but monodisperse poly(acrylic acid)-b-poly(n-butyl acrylate) block copolymers, PAA-b-PBA, with a short PAA block and a long PBA block. In the course of the surfactant-free emulsion polymerization, core-shell particles form in water, with the short hydrophilic block located...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.