Hydroxyl-terminated

Uses. The largest uses of butanediol are internal consumption in manufacture of tetrahydrofuran and butyrolactone (145). The largest merchant uses are for poly(butylene terephthalate) resins (see Polyesters,thermoplastic) and in polyurethanes, both as a chain extender and as an ingredient in a hydroxyl-terminated polyester used as a macroglycol. Butanediol is also used as a solvent, as a monomer for vadous condensation polymers, and as an intermediate in the manufacture of other chemicals. 

Condensation siHcone materials are based on hydroxyl-terminated polydimethylsiloxane and are made in the form of two paste or paste—Hquid catalyst systems. 

Tirrell et al. [42,43] studied the role of interfacial chains in a more detailed fashion. Tirrell et al. [42,43] used a crosslinked PDMS cap in contact with a silicon wafer on to which a,o)-hydroxyl terminated PDMS chains are tethered by adsorption from a solution. The molecular weight of the narrow disperse PDMS samples was in the range of 20,000-700,000. The surface chain density was given by27 yj g e 0 is the volume fraction of PDMS in solution. 

Common crosslinkers for hydroxyl-terminated PUD s are water-dispersible isocyanates and melamines. Unlike other crosslinkers, melamine crosslinkers usually have good stability in water. Two major drawbacks are associated with melamine crosslinking. In the first place, the bond must be heated. It will not... 

TPU is usually made from hydroxyl-terminated polyether or polyester diols, diisocyanates, and bifunctional chain extenders. Since the composition, the synthetic method, molecular weight, and its distribution are all changeable, there are numerous types of TPUs available, and their prices and properties vary significantly. 

Apart from poly(ethylene glycol), other hydroxyl-terminated polymers and low-molecular weight compounds were condensed with ACPC. An interesting example is the reaction of ACPC with preformed poly(bu-tadiene) possessing terminal OH groups [26]. The reaction was carried out in chloroform solution and (CH3CH2)3N was used as a catalyst. MAIs based on butadiene thus obtained were used for the thermally induced block copolymerization with styrene [26] and dimethyl itaconate [27]. 

Generation of radicals by redox reactions has also been applied for synthesizing block copolymers. As was mentioned in Section II. D. (see Scheme 23), Ce(IV) is able to form radical sites in hydroxyl-terminated compounds. Thus, Erim et al. [116] produced a hydroxyl-terminated poly(acrylamid) by thermal polymerization using 4,4-azobis(4-cyano pentanol). The polymer formed was in a second step treated with ceric (IV) ammonium nitrate, hence generating oxygen centered radicals capable of starting a second free radical polymeriza-... 

The isocyanate group is more reactive than the epoxy group in that it will react at room temperature with water and hydroxyl groups as well as with amine groups. However, the latter reaction is too fast to be practicable so the standard two-pack coatings are based on isocyanate and polyhydroxyl prepolymers such as hydroxyl terminated polyesters or polyethers as in the last example given in the section on epoxy resins. 

Brosse, J.-C., Derouet, D., Epaillard, F., Soutif, J.-C., Legeay, G. and Dusek, K. Hydroxyl-Terminated Polymers Obtained by Free Radical Polymerization. Synthesis, Characterization, and Applications. Vol. 81, pp. 167—224. 

Block copolymers with materials such as a polyester (PE) (qv) can be prepd by the reaction of diisocyanate-terminated polyesters with hydroxyl-terminated PMMA according to Wilkes and Grezlak (Ref 21). The basic structure was found to be PMMA-PE-FMMA, with a mw of from 7500 to 47000. The purpose of the work was to produce a stronger copolymer (in terms of stress-strain) by tailoring the amt of each monomer used to produce the copolymer Further information on polymerization can be found in Refs 2a 6a... 

Polystyrene-Woc -polysulfone-/ /oc -polystyrene and poly(butyl acrylate)-Woc -polysulfone-/ /oc -poly(butyl acrylate) triblock copolymers were prepared using a macroinitiator.214 The hydroxyl-terminated polysulfone was allowed to react with 2-bromopropionyl bromide, an atomic transfer radical polymerization (ATRP) initiator, in the presence of pyridine. The modified macroinitiator could initiate die styrene polymerization under controlled conditions. 

Multiblock polyethylene-polydimethylsiloxane copolymers were obtained by the reaction of silane terminated PDMS and hydroxyl terminated polyethylene oligomers in the presence of stannous octoate as the catalyst 254). The reactions were conducted in refluxing xylene for 24 hours. PDMS block size was kept constant at 3,200 g/mole, whereas polyethylene segment molecular weights were varied between 1,200 and 6,500 g/mole. Thermal analysis and dynamic mechanical studies of the copolymers showed the formation of two-phase structures with crystalline polyethylene segments. 

Waste PETP was depolymerised by glycolysis to give hydroxyl-terminated oligomers(DPET), which were used in the synthesis of urethane oils. The effect of depolymerisation temps., the type of glycol and the amount of catalyst on the yield and composition of the depolymerisation products was studied. The physical properties of the urethane oils were compared with those of a commercially-available product. The reaction of DPET with isocyanates produced random linkage between different molecules with or without terephthaloyl groups. 15 refs. 

Recently Sahoo and Bhowmick [75] synthesized hydroxyl-terminated POSS in their laboratory starting from (3-aminopropyl) triethoxysilane (APS) and phenylglycidylether (PGE) and used it as a curative in carboxylated nitrile mbber (XNBR). This has been a newer class of material where the nanofiller simultaneously cures the mbber and promotes solvent resistance, as well as mechanical and dynamic mechanical properties. Table 3.3 illustrates some of these findings. 

Polyether-based thermoplastic copolyesters show a tendency toward oxidative degradation and hydrolysis at elevated temperature, which makes the use of stabilizer necessary. The problem could be overcome by incorporation of polyolehnic soft segments in PBT-based copolyesters [31,32]. Schmalz et al. [33] have proposed recently a more useful technique to incorporate nonpolar segments in PBT-based copolyesters. This involves a conventional two-step melt polycondensation of hydroxyl-terminated PEO-PEB-PEO (synthesized by chain extension of hydroxyl-terminated hydrogenated polybutadienes with ethylene oxide) and PBT-based copolyesters. 

Singer S.M. and Allot M.T., Thermoplastic polyurethane elastomer based on a saturated hydroxyl terminated polyol, difunctional aromatic chain extender and 1,5-naphthalene diisocyanate, US Patent 5 599 874, 1997. 

Recently, Cohn and Salomon synthesized and characterized a series of PLCL thermoplastic bioelastomers by two-step synthesis procedure. First, ring-opening polymerization of L-lactide initiated by the hydroxyl terminal groups of the PCL chain. Second, chain extension polymerization of these PLA-PCL-PLA triblocks initiated by the hexamethylene diisocyanate (HDl). 

Liquid rubbers In order to improve the flexibihty of short glass fiber-reinforced epoxy composites, Kaynak et al. [53] modified the epoxy resin matrix with hydroxyl-terminated polybutadiene (HTPB) liquid mbber. A silane coupling agent was also used to improve the interfacial adhesion between glass fibers and epoxy matrix. However, Humpidge et al. [54] reported some unique processing problems for the resulting pasty mixmres when short textile fibers were incorporated in a hquid mbber medium. 

The effects of the feed ratio in the lipase CA-catalyzed polymerization of adipic acid and 1,6-hexanediol were examined by using NMR and MALDI-TOF mass spectroscopies. NMR analysis showed that the hydroxyl terminated product was preferentially formed at the early stage of the polymerization in the stoichiometric substrates. As the reaction proceeded, the carboxyl-terminated product was mainly formed. Even in the use of an excess of the dicarboxylic acid monomer, the hydroxy-terminated polymer was predominantly formed at the early reaction stage, which is a specific polymerization behavior due to the unique enzyme catalysis. 

Poly(methyl 3-(l-oxypyridinyl)siloxane) was synthesized and shown to have catalytic activity in transacylation reactions of carboxylic and phosphoric acid derivatives. 3-(Methyldichlorosilyl)pyridine (1) was made by metallation of 3-bromopyridine with n-BuLi followed by reaction with excess MeSiCl3. 1 was hydrolyzed in aqueous ammonia to give hydroxyl terminated poly(methyl 3-pyridinylsiloxane) (2) which was end-blocked to polymer 3 with (Me3Si)2NH and Me3SiCl. Polymer 3 was N-oxidized with m-ClC6H4C03H to give 4. Species 1-4 were characterized by IR and H NMR spectra. MS of 1 and thermal analysis (DSC and TGA) of 2-4 are discussed. 3-(Trimethylsilyl)-pyridine 1-oxide (6), l,3-dimethyl-l,3-bis-3-(l-oxypyridinyl) disiloxane (7) and 4 were effective catalysts for conversion of benzoyl chloride to benzoic anhydride in CH2Cl2/aqueous NaHCC>3 suspensions and for hydrolysis of diphenyl phosphorochloridate in aqueous NaHCC>3. The latter had a ti/2 of less than 10 min at 23°C. 

We can make polyurethanes via one- or two-step operations. In the single-stage process, diols and isocyanates react directly to form polymers. If we wish to make thermoplastic linear polymers, we use only diisocyanates. When thermosets are required, we use a mixture of diisocyanates and tri- or polyisocyanates residues of the latter becoming crosslinks between chains. In the first step of the two-stage process, we make oligomers known as prepolymers, which are terminated either by isocyanate or hydroxyl groups. Polymers are formed in the second step, when the isocyanate terminated prepolymers react with diol chain extenders, or the hydroxyl terminated prepolymers react with di- or polyisocyanates. 

We create polyurethanes from prepolymers by chain extension. In the case of hydroxyl-terminated prepolymers the chain extender is an isocyanate. If we use a diisocyanate, the resulting polymer is linear. If we substitute some or all of the diisocyanate with a tri- or... 

The compound was examined as a propellant explosive, it proved easily detonable and more sensitive than ammonium perchlorate. A formulation with hydroxyl terminated poly butadiene binder ignited spontaneously at room temperature [1]. Other workers have found it more tractable [2]. 

There are now a number of techniques which may be used to prepare elastomeric networks of known structure Q-8). Two particularly useful and convenient ones involve the multi-functional end-linking of hydroxyl-terminated (4-16) or vinyl-terminated polydimethylsiloxane (PDMS) chains (3,17-21), and the cross-linking of PDMS chains through vinyl side groups present in known amounts and in known locations along the chains (4,18,22-25). A typical reaction of this type is... 

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