نتایج جستجو برای: ring opening polymerization
تعداد نتایج: 195988 فیلتر نتایج به سال:
Herein, we report the use of acid/base complexes for the ring opening polymerization of (L)-lactide. The salt formed from an equimolar reaction of benzoic acid and DBU produced a catalyst capable of controlled polymerizations allowing for targeted molecular weights and narrow polydispersities. The use of computational analysis suggests a bifunctional catalytic mechanism wherein both the monomer...
a mild, green and highly efficient route for regio-selective amination of oxiranes was developed via incorporation of mn(ii), fe(ii), co(ii), ni(ii), cu(ii) and zn(ii) cations onto the surface of hydroxyapatite-encapsulated γ-fe2o3 nanoparticles (γ-fe2o3@hap). among six magnetically recoverable catalytic systems denoted as [γ-fe2o3@hap-mii], the catalyst in which m designated as fe(ii) showed t...
polydimethylsiloxane (pdms) has been synthesized by ring-opening polymerization of octamethylcyclotetrasiloxane (d4) in microemulsion with acidic catalyst. the structure and properties of microemulsion were characterized by transmission electron microscopy (tem), fourier transform infrared spectroscopy (ft-ir), photo correlation spectroscopy (pcs). the effect of the variation in ph value, amoun...
Sulfonylaziridines have been identified as excellent monomers for living ring-opening polymerization initiated by nucleophilic sulfonylamides. The resulting polymers exhibit low polydispersities and controllable molecular weights. The enantiopurity of the monomer plays a key role: racemic samples yield soluble polymers of target molecular weights, while enantiopure samples produce insoluble pol...
In this paper we report on the preparation of calix[8]arene functionalized polyglycerol nanogels by miniemulsion polymerization. The gel macromonomers were prepared by anionic ring-opening multibranching polymerization of glycidol using calix[8]arene as initiator. 1,1 ,3,3,3 ,3 -hexamethyl-2,2 -indotricarbocyanine iodide (HITC) red fluorescent dye was used as a guest molecule. Photobleaching up...
The uranyl aryloxide, [UO(2)(OAr)(2)(THF)(2)], and uranyl chloride, [UO(2)Cl(2)(THF)(3)] or [UO(2)Cl(2)(THF)(2)](2) act as pre-catalysts for the ring opening polymerization of propylene oxide and cyclohexene oxide. Coordination of the monomers has been investigated using (1)H EXSY spectroscopy and kinetic and thermodynamic parameters reported. NMR analyses of the polymers suggest a bimetallic m...
Epoxide-amine oligo-adducts were synthesized via a one-pot microwave assisted heterogeneous catalytic transfer hydrogenation. Accordingly, 4-nitroanisole was reduced under microwave conditions to give 4-aminoanisole which reacted immediately with the diglycidyl ether of bisphenol A in an addition polymerization reaction to yield oligo(amino alcohol)s. The hydroxy groups of the new formed oligom...
Polyesters, especially poly(lactide) (PLA), are used widely as biodegradable and biocompatible materials, yet their controllable synthesis, especially the stereoselective synthesis of polyesters, is still a challenge. Recently some excellent Lewis pair catalysts for ring-opening polymerization (ROP) of lactide and related cyclic esters have emerged. This review article will highlight the key ad...
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