نتایج جستجو برای: step growth polymerization
تعداد نتایج: 1095121 فیلتر نتایج به سال:
Polymerization-induced self-assembly (PISA) is used to prepare linear poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate)-poly(benzyl methacrylate) [PGMA-PHPMA-PBzMA] triblock copolymer nano-objects in the form of a concentrated aqueous dispersion via a three-step synthesis based on reversible addition-fragmentation chain transfer (RAFT) polymerization. First, GMA is polymerized ...
Supramolecular polymers are a class of materials characterized by a repetition of monomer units held together by non-covalent forces such as metal coordination, π–π interactions and hydrogen bonding1–4. Compared with their covalent counterparts the unique properties of these polymers have attracted considerable attention, for instance, the self-healing ability that arises from the thermodynamic...
The mechanism of polymerization of methacrylonitrile initiated by triethylphosphine in dimethylformamide and tetrahydrofuran was investigated. The elemental analysis has shown that phosphorus is chemically bound to the polymeric molecules. Analysis by NMR spectroscopy, as well as conductivity measurements, prove that the zwitter-ion structure is formed in the initiation process Monomer addition...
The transformation of a transected axonal tip into a growth cone (GC) after axotomy is a critical step in the cascade of events leading to regeneration. However, the mechanisms underlying it are largely unknown. In earlier studies we reported that axotomy of cultured Aplysia neurons leads to a transient and local increase in the free intracellular Ca2+ concentration, calpain activation, and loc...
Selective adsorption of L- and D-amino acids on calcite: Implications for biochemical homochirality.
The emergence of biochemical homochirality was a key step in the origin of life, yet prebiotic mechanisms for chiral separation are not well constrained. Here we demonstrate a geochemically plausible scenario for chiral separation of amino acids by adsorption on mineral surfaces. Crystals of the common rock-forming mineral calcite (CaCO(3)), when immersed in a racemic aspartic acid solution, di...
ion of the proton from the amino group of the monomer (phenyl 4-(alkylamino)benzoate) by the base, the reactivity of the phenyl ester moiety is deactivated, which prevents monomers from reacting with each other. The anion produced by proton abstraction from the monomer will only react with initiator, leading to an activated monomer that possesses a more reactive phenyl ester moiety compared to ...
Hyperbranched macromolecules (HMs, also called hyperbranched polymers) are highly branched three-dimensional (3D) structures in which all bonds converge to a focal point or core, and which have a multiplicity of reactive chain-ends. This review summarizes major types of synthetic strategies exploited to produce HMs, including the step-growth polycondensation, the self-condensing vinyl polymeriz...
The use of photoinitiated polymerization is continuously growing in industry as reflected by the large number of applications in not only conventional areas such as coatings, inks, and adhesives but also high-tech domains, optoelectronics, laser imaging, stereolithography, and nanotechnology. In this Perspective, the latest developments in photoinitiating systems for free radical and cationic p...
The aim of this study was to enhance the bond strength of one-step bonding agents to dentin. In particular, the focus was on using Catabrush the applicator system of AQ Bond Plus. Catabrush was supplemented with N-phenylglycine and aromatic sulfinate as polymerization accelerators, as N-phenylglycine was reportedly beneficial in improving the bond strength to dentin. The results indicated that ...
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