Showing papers on "Polytetrahydrofuran published in 2005"

Preparation of star block co-polymers by combination of cationic ring opening polymerization and atom transfer radical polymerization

Abstract: The synthesis of star block co-polymers with polytetrahydrofuran (PTHF) core and poly(tert-butyl acrylate) (PtBA) shell was performed using a dual initiator, 4-hydroxy butyl bromoisobutyrate, by combination of cationic ring-opening polymerization (CROP) and atom transfer radical polymerization (ATRP). The in situ reaction of the hydroxyl groups originating from the dual initiator with trifluoromethane sulfonic anhydride provides a triflate ester initiating group for the CROP of THF. PTHF star polymers having three arms with tertiary bromide end groups (PTHF)3 have been prepared by reaction of living PTHF chains with tris(2-aminoethyl)amine (TAEA) in the presence of 2,2,6,6-tetramethylpiperidine (TMP) as a proton trap. Subsequently, the star polymers were used as macroinitiators for the ATRP of tBA using the CuBr/N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA) catalyst system to obtain the tri-armed star block co-polymers (PTHF-b-PtBA)3. The polymers were characterized with gel-permeation chromatograph...

Cross-linked polytetrahydrofuran-containing polyurethanes

Abstract: The invention relates to a cross-linked polyurethane, which contains, in an integrated manner, at least one polytetrahydrofuran and one polyisocyanate mixture, to cosmetic or pharmaceutical agents containing a polyurethane of the aforementioned type, and to the use of these polyurethanes.

Conducting copolymers of polytetrahydrofuran and their electrochromic properties

Abstract: Living polytetrahydrofuran (PTHF) was terminated with sodium thiophene methonate to yield a polymer with a thiophene group at one end. Copolymerizations of PTHF with pyrrole and thiophene were achieved in water-p-toluene sulfonic acid and acetonitrile-tetrabutylammonium tetrafluoroborate (TBAFB) solvent-electrolyte couples via constant potential electrolyses. Characterizations of the samples were performed by NMR, cyclic voltammetry, FT-IR, thermal analyses, and scanning electron microscopy. Electrical conductivities were measured by the four-probe technique. PTHF/PTh film that was deposited on ITO-glass in a dichloromethane-TBAFB solvent-electrolyte couple was found to exhibit electrochromic behavior and it electrochemically switches between blue oxidized and red reduced states. Optical analyses were carried out to investigate the electronic structure of PTHF/PTh electrochromic copolymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1014–1023, 2005

Process for preparing water-soluble copolyester

Abstract: The water soluble copolyester is prepared with polytetrahydrofuran in number average molecular weight of 350-20000 as the fourth component, and metaphthalate-5-sodium sulfonate, metaphthalate dihydroxyethyl-5-sodium sulfonate, metaphthalate dimethyl-5-potassium sulfonate, or other metaphthalate type sulfonate as the third component, and through polycondensation in PTA or DMT path. Compared with the copolyester with polyglycol and other aliphatic flexible compound as the fourth component, the present invention is water soluble and has better crystallizing performance. The product produces no adhesion during drying, and may be blended with conventional polyester slice to obtain POY sea island cotton with flexible elastic process to raise the spinnability and processibility of sea island fiber.

Synthesis and Characterization of N-Polyethylene Glycol Monomethyl Ether Substituted Polyurethane

Abstract: Poly(N-substituted urethane)s with different molecular weights of polyethylene glycol monomethyl ether side chain were synthesized form sodium hydride, chlorinated polyethylene glycol monomethyl ether (PEGMME), and polyether and poly ester urethane containing polytetrahydrofuran or polycaprolactone/toluene diisocyanate and 1,4-butanediol. The chemical structures were characterized with FTIR and FT-1H NMR. To investigate the effect of different MW of N-substituted side chain on the morphology, thermal property and particle size distribution of the final product, we used differential scanning calorimetry and laser light scattering. N-Substitution of polyurethane had significant influences on thermal properties and solubility of the resulting material. Tg of the N-substituted urethane decreases with N-substitution and gradually increases with increasing molecular weight of the substituted side chain. This is more obvious in higher molecular weight. The particle size of final water borne PU emulsion also decreases with increasing MW of PEGMME. The decreasing particle size may be due to increased chain flexibility and or hydrophilicity of N-substituted polyurethanes.

Thermoplastic polyurethanes containing polytetrahydrofurans of vaarious molecular weights

Abstract: The invention relates to thermoplastic polyurethanes made from polytetrahydrofuran, whereby the polytetrahydrofuran is a mixture (i) with a number average molecular weight between 1200 g/mol and 1500 g/mol, the weight proportion of the polytetrahydrofurans with a polymerisation degree of less than or equal to 14 is greater than 21 wt.% with relation to the total weight of the polytetrahydrofurans in the mixture and the weight proportion of the polytetrahydrofurans with polymerisation degree of greater than 40 is less than 40 wt.%, with relation to the total weight of the polytetrahydrofurans in the mixture.

Polytetrahydrofuran- and dendrimer- based novel sol-gel coatings for capillary microextraction (cme) providing parts per trillion (ppt) and parts per quadrillion (ppq) level detection limits in conjunction with gas chromatography and flame ionization detection (fid)

Abstract: xx Chapter One : Solid Phase Microextraction-A Solvent-Free Sample Preparation Technique 1 1.

Advances in production technology for polytetrahydrofuran and consideration about R&D in China

Abstract: Five processes for production of polytetrahydrofuran are introduced as follows:catalyzed by ①perchloric acid,②flurosulfonic acid,③Nafion resin,④activated montmorillonite,and ⑤heteropolyacids.The superiorities and defects of various technologies are analyzed,and their development trends are summarized.Though China has become the largest producer and consumer of polytetrahydrofuran,over many years of RD,these processes have not yet achieved a commercial scale of production in China.The causes are analyzed and means for resolution is suggested.