Ethylene oxide terminator

Reed 332) has reported that reaction of ethylene oxide with the a,(a-dilithiumpoly-butadiene in predominantly hydrocarbon media (some residual ether from the dilithium initiator preparation was present) produced telechelic polybutadienes with hydroxyl functionalities (determined by infrared spectroscopy) of 2.0 + 0.1 in most cases. A recent report by Morton, et al.146) confirms the efficiency of the ethylene oxide termination reaction for a,ta-dilithiumpolyisoprene functionalities of 1.99, 1.92 and 2.0j were reported (determined by titration using Method B of ASTM method E222-66). It should be noted, however, that term of a, co-dilithium-polymers with ethylene oxide resulted in gel formation which required 1-4 days for completion. In general, epoxides are not polymerized by lithium bases 333,334), presumably because of the unreactivity of the strongly associated lithium alkoxides641 which are formed. With counter ions such as sodium or potassium, reaction of the polymeric anions with ethylene oxide will effect polymerization to form block copolymers (Eq. (80) 334 336>). 

Scheme 1. Idealized sketch of a protein resistant gold surface with specific affinity for an analyte (a protein) prepared by chemisorption of a mixed hydroxylic-terminated alkylthiol and a oligo(ethylene oxide)-terminated alkylthiol having an end-attached affinity Ugand [107].

Reed has reported that reaction of ethylene oxide with the a,(a-dilithiumpoly-butadiene in predominantly hydrocarbon media (some residual ether from the dilithium initiator preparation was present) produced telechelic polybutadienes with hydroxyl functionalities (determined by infrared spectroscopy) of 2.0 + 0.1 in most cases. A recent report by Morton, et al. confirms the efficiency of the ethylene oxide termination reaction for a,ta-dilithiumpolyisoprene functionalities of 1.9, 1.92 - i reported (determined by titration using Method B of ASTM... 

Quirk and co-workers [25] evaluated the amount of chain transfer to monomer during the alkyl lithium initiated polymerisation of 1,3 cyclohexadiene. This was achieved by characterisation of the products from ethylene oxide termination. The products were separated by SEC, thin layer chromatography, proton magnetic resonance spectroscopy and MALDI-ToF spectroscopy. 

Oligomeric ethylene oxide terminated with l,2,4-triazoline-3,5-dione has been grafted onto polybutadiene at room temperature in a mixture of tetrahydrofuran and ethylene chloride (53). The product had a broad molecular weight distribution, and energy absorption maxima related to the glass transition temperature of each polymer were apparent. 

When poly(siloxane-ethylene oxide) terminated with acrylate end caps (for example. Figure 11.5) is used as a polymer matrix, after cross-linking and... 

A block copolymer of PS and an oxazoline was obtained from an OTs-terminated PS, which was obtained by ethylene oxide termination of PSLi in THE at —78°C followed by addition of tosylchloride. The OTs-terminated polymer served as a cationic macroinitiator for EOz (Mn per block 10-20 kg/ mol, Mw/Mn = 1.3—1.5), which means that control of the EOz polymerisation is limited [145]. Another oxazoline block copolymer was obtained via the polymerisation of EO by a potassium difunctional initiator under /THE/ KPDP/RT//MSC1/ conditions. The a, co-acetal-methylsulfone-terminated PEO was used as a macroinitiator for the cationic polymerisation of 2MOz in nitromethane to yield acetal-terminated PEO-P2MOz, which was hydrolysed to removed the acetyl side chains to yield PEO-PEI (M = 3.2kg/mol MJMn = 1.04 for the PEO 5 < Mn/(kg/mol) < 10.5 1.35 < MJM < 1.56 for the PEO-PEI) [146]. 

Poly(ethylene oxide), terminal functional groups, linear... 

Poly(ethylene oxide)s [25372-68-3] are made by condensation of ethylene oxide with a basic catalyst. In order to achieve a very high molecular weight, water and other compounds that can act as chain terminators must be rigorously excluded. Polymers up to a molecular weight of 8 million are available commercially in the form of dry powders (27). These must be dissolved carefliUy using similar techniques to those used for dry polyacrylamides. Poly(ethylene oxide)s precipitate from water solutions just below the boiling point (see Polyethers, ethylene oxide polymers). 

The major use of 4-cumylphenol is as a chain terminator for polycarbonates. Its use in place of phenol gives a polycarbonate with superior properties (33). Eor a low molecular weight polycarbonate used for injection-molding appHcations, the use of 4-cumylphenol as a chain terminator significantly lowers the volatiHty of the resin. Other uses of 4-cumylphenol include the production of phenoHc resins, some of which have appHcations in the electronics industry (34). Another appHcation of 4-cumylphenol involves its reaction with ethylene oxide to form a specialty surfactant. 

This is a particularly troublesome competing reaction when the olefin oxide, eg, ethylene oxide, produces the more reactive terminal primary hydroxy group. Glycol ethers are used as solvents ia lacquers, enamels, and waterborne coatings to improve gloss and flow. 

Carboxylic Acid Esters. In the carboxyflc acid ester series of surfactants, the hydrophobe, a naturally occurring fatty acid, is solubilized with the hydroxyl groups of polyols or the ether and terminal hydroxyl groups of ethylene oxide chains. 

Polyall lene Oxide Block Copolymers. The higher alkylene oxides derived from propjiene, butylene, styrene (qv), and cyclohexene react with active oxygens in a manner analogous to the reaction of ethylene oxide. Because the hydrophilic oxygen constitutes a smaller proportion of these molecules, the net effect is that the oxides, unlike ethylene oxide, are hydrophobic. The higher oxides are not used commercially as surfactant raw materials except for minor quantities that are employed as chain terminators in polyoxyethylene surfactants to lower the foaming tendency. The hydrophobic nature of propylene oxide units, —CH(CH2)CH20—, has been utilized in several ways in the manufacture of surfactants. Manufacture, properties, and uses of poly(oxyethylene- (9-oxypropylene) have been reviewed (98). 

The experimental setup used for the first bipolar or wireless NEMCA study is shown in Figure 12.6.8 An YSZ disc with two terminal Au electrodes and one Pt catalyst film deposited on one side and a reference Au electrode on the other side is placed in a single-chamber reactor. Ethylene oxidation on the Pt catalyst film was chosen as a model reaction.8... 

Figure 12.8. Transient effect of an applied potential, UAP, between the two terminal gold electrodes (30 V) on the catalytic rate of ethylene oxidation (expressed in mol O/s) for dotted (filled circles) and multi-striped (open circles) platinum configuration.10 Reprinted with permission from Elsevier Science.

Paraformaldehyde/DMSO dissolves cellulose rapidly, with neghgible degradation, and forms the hydoxymethyl (methylol) derivative at Ce [ 140-142]. Therefore, cellulose derivatives at the secondary carbon atoms are easily obtained after (ready) hydrolysis of the methylol residue. Additionally, fresh formaldehyde may add to the methylol group, resulting in longer methylene oxide chains, that can be functionahzed at the terminal OH group, akin to non-ionic, ethylene oxide-based surfactants [143,144]. 

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. 

The living nature of PCL obtained in the presence of Zn(OAl-(OPri)2)2 has been used to prepare both di- and triblock copolymers of e-caprolactone and lactic acid (42,43). Treatment of the initial living PCL with dilactide afforded a PCL-PLA diblock with M /Mn = 1.12, with each block length determined by the proportions of the reactants, i.e., the ratio of [monomer]/[Zn]. While the living diblock copolymer continued to initiate dilactide polymerization, it failed to initiate e-caprolactone polymerization. To obtain a PCL-PLA-PCL triblock, it was necessary to treat the living PCL-PLA-OAIR2 intermediate with ethylene oxide, then activate the hydroxy-terminated PCL-PLA-(OCH2CH2)nOH with a modified Teyssie catalyst (Fig. 5). 

II. B polyethylene glycol, ethylene oxide, polystyrene, diisocyanates (urethanes), polyvinylchloride, chloroprene, THF, diglycolide, dilac-tide, <5-valerolactone, substituted e-caprolactones, 4-vinyl anisole, styrene, methyl methacrylate, and vinyl acetate. In addition to these species, many copolymers have been prepared from oligomers of PCL. In particular, a variety of polyester-urethanes have been synthesized from hydroxy-terminated PCL, some of which have achieved commercial status (9). Graft copolymers with acrylic acid, acrylonitrile, and styrene have been prepared using PCL as the backbone polymer (60). 

The sterilization processes described in the Ph Eur are preferred, especially terminal sterilization in the final container alternative processes have to be justified. All sterilization processes will need to be described and appropriate in-process controls and limits included. Where Ph Eur prescriptions are followed, there should be a statement to this effect in the application. Most of this information should be discussed in the development pharmaceutics section. Reference is made to the specific guidelines on ethylene oxide sterilization and irradiation sterilization, which are discussed further below. The possibility of parametric release for terminal processes such as saturated steam and irradiation is mentioned (see below). For all sterile products there should be a sterility requirement included in the finished product specification regardless of the outcome of validation studies. 

PS-fr-PBd) star-block copolymers were synthesized by the macromonomer technique in combination with anionic polymerization and ROMP [ 158], following the procedure outlined in Scheme 83. The macromonomers were prepared with two different methods. In the first the living diblock copolymer was reacted with ethylene oxide to reduce the nucleophihcity of the living end followed by termination with 5-carbonyl chloride bicycle (2.2.1) hept-2-ene, while in the second method the functional initiator 5-lithiomethyl bicycle... 

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