Effects and measurements of polyoxyethylene block length in polyoxyethylene-polyoxybutylene copolymers

Block copolymer surfactants, made from 1,2-butylene oxide (BO), propylene oxide (PO) and ethylene oxide (EO), exhibit wide ranges of properties and performance. In particular, BO/EO block copolymers exhibit improved surfactant performance with respect to PO/EO analogs. One interesting difference between these two classes of surfactants is the EO capping efficiency of polyoxypropylene (POP) vs. polyoxybutylene (POB) hydrophobe secondary hydroxyl groups. In this regard, nuclear magnetic resonance measurements have shown that POP secondary diols react more readily with EO than POB diols. For the case of ethoxylated POB polymers, the amount of unethoxylated secondary hydroxyl is proportional to the average length of the polyoxyethylene (POE) blocks. Differential scanning calorimetry was used to observe crystallinity of POE blocks. For a given POB hydrophobe molecular weight and weight percentage EO, surfactant performance properties can be augmented by affecting POE block length in the ethoxylation process.     

KINETIC ANALYSIS OF COMPLEX REACTION SYSTEMS-METHANOL CONVERSION TO LOW MOLECULAR WEIGHT OLEFINS

An analysis of the selectivity data when converting methanol to low molecular weight hydrocarbons suggests that methane, propylene and propane are formed by the primary reaction of methanol decomposition, Ethane, carbon monoxide and dimethyl ether are formed by primary reactions and participate in secondary reactions. Carbon dioxide and ethylene are produced by secondary reactions.     

KINETIC ANALYSIS OF COMPLEX REACTION SYSTEMS-METHANOL CONVERSION TO LOW MOLECULAR WEIGHT OLEFINS

An analysis of the selectivity data when converting methanol to low molecular weight hydrocarbons suggests that methane, propylene and propane are formed by the primary reaction of methanol decomposition, Ethane, carbon monoxide and dimethyl ether are formed by primary reactions and participate in secondary reactions. Carbon dioxide and ethylene are produced by secondary reactions.     

Regioselective Alkoxylation of 2,2,4-Trimethyl-1,3-pentanediol

An efficient procedure for the regioselective synthesis of secondary alcohol alkoxylates from 2,2,4-trimethyl-1,3-pentanediol (TMPD) is described. TMPD was reacted with propylene oxide followed by ethylene oxide in the presence of a catalytic amount of alkali metal hydroxide to form secondary alcohol alkoxylates. Instead of a mixture of compounds resulting from the reaction of TMPD and propylene oxide, the primary hydroxyl group of the TMPD reacted to form predominantly 2,2,4-trimethyl-3-hydroxypentylpropoxylate as the major product. On further ethoxylation the less hindered secondary hydroxyl group of the 2,2,4-trimethyl-3-hydroxypentylpropoxylate reacted predominantly. ¹³C NMR indicated that the secondary hydroxyl group (96.2 mol%) of TMPD remained unreacted during alkoxylation.     

Tetrahydrofuran-propylene oxide copolymers: 1. End-group analysis by 13C n.m.r. and the mechanistic inferences

The boron trifluoride catalysed copolymerization of tetrahydrofuran and propylene oxide in the presence of 1,4-butanediol leads to linear, difunctional copolymers. The ¹³C n.m.r. spectra of these copolymers are exceptionally informative in that the compositions, the molecular weights and the types of end-groups can all be obtained independently from both regions of the spectrum. The types of end-groups were identified by an off-resonance and a gated decoupling technique. No tetrahydrofuran end-groups were found. Only propylene oxide end-groups with a 2:1 ratio of secondary alcohol to primary alcohol were observed, regardless of the composition or the molecular weight of the polymer. The propylene oxide end-groups of the copolymer are considered to be formed by initial propagation reactions. These reactions are the attack of either monomer on the protonated propylene oxide to open the oxirane ring and form a cyclic oxonium ion. Attack on protonated tetrahydrofuran is thought not to lead to initiation. 1,4-Butanediol serves as a chain transfer agent and thereby regulates the molecular weight of the copolymer. Polymerization stops when all propylene oxide has been consumed because no new chains can be initiated by the remaining tetrahydrofuran.     

The determination of adjacent oxypropylene–oxyethylene units in propylene oxide–ethylene oxide adducts by infrared spectroscopy

A study of several base-catalyzed propylene oxide—ethylene oxide adducts of glycerin and certain model compounds has shown that an infrared absorption band at 10.30 μ can be associated with a structural entity represented by an oxyethylene unit attached to an oxypropylene unit at the secondary position. Coupled with other information such as total oxyethylene content and primary hydroxyl content, this finding has proved most useful in differentiating average molecular structure for commercial polyether polyols used in the manufacture of polyurethanes.     

Synthesis and characterization of polystyrene-poly(ethylene oxide) graft copolymers

Amphiphilic graft copolymers have been synthesized. The grafting reaction proceeds by anionic deactivation of a ‘living’ monofunctional poly(ethylene oxide) onto a partly chloromethylated polystyrene backbone. The copolymers are well-defined compounds (molecular weight of the backbone, number and length of the grafts are known), which exhibit narrow molecular weight distribution and are shown to be homogeneous in composition. The degree of grafting is high. Light scattering, vapour pressure osmometry, ultra-violet spectroscopy, nuclear magnetic resonance, differential refractometry and gel permeation chromatography were used for an accurate characterization of the structure of these copolymers.     

Oxypropylation of fatty alcohols,and the sulfation products

Reaction of propylene oxide, rather than ethylene oxide, with fatty alcohols, gives a higher yield (50%) of mono-oxyalkylation product because the secondary alcohol formed is less reactive than the primary alcohol formed with ethylene oxide. Rate of further reaction is about half the rate of the parent primary alcohol. Distributuon of propylene oxide reaction products follows the Weibull-Nycander equation. Analysis of reaction products was accomplished by gas-liquid chromatography of the acetylated ether alcohol mixtures. Pure mono-oxypropylated alcohols ROCH₂CHOHCH₃ and in some cases dioxypropylated alcohols R[OCH₂CH(CH₃)]₂OH were separated by fractional distillation. Individual ether alcohols and products with a known average number of oxypropyl groups were sulfated and evaluated in terms of Krafft point, critical micelle concentration, detergency, foam height and lime soap dispersing properties. Incorporation of one oxypropyl group was more effective than the same degree of oxyethylation, and improved solubility with no significant loss in foaming and detergency. Ether alcohol sulfates from propylene oxide are stable to alkaline hydrolysis and nearly equal to the sulfates from ethylene oxide in their stability to acid hydrolysis. Presented at the AOCS Meeting in Cincinnati, 1965. E. Utiliz. Res. Dev. Div., ARS. USDA.     

Generation of microcellular polyurethane foams via polymerization in carbon dioxide. I: Phase behavior of polyurethane precursors

On investigating the generation of microcellular polyurethane foam via reaction in carbon dioxide, we have observed that common polyurethane precursors are CO₂ miscible, whereas typically fluorinated compounds or specially designed surfactants are needed to solubilize polymers in CO₂. Both isocyanates and polyols are CO₂-miscible at workable pressures and temperatures and in useful concentrations to allow generation of polyurethane foams in CO₂. By characterizing the phase behavior of several series of propylene oxide and ethylene oxide polyols, we have observed that the combined effects of molecular weight and hydroxyl number fix the location of the phase separation pressures. In general, lower molecular weights and lower hydroxyl mole fractions produce phase boundaries at relatively lower pressures in carbon dioxide. It also has been shown that CO₂-soluble compounds may have a com̀patibilizing effect on less CO₂-soluble materials.     

Oligomeric Composition of Polyols From Fatty Acid Methyl Ester: The Effect of Ring‐Opening Reactants of Epoxide Groups

Commercial availability of fatty acid methyl ester (FAME) from palm oil targeted for biodiesel offers a good feedstock for the production of structurally well‐defined polyols for polyurethane applications. The effect of molecular weight (MW), odd and even carbon numbers, and the linear and branched structure reactants used in the ring‐opening reaction of epoxidized fatty acid methyl ester (E‐FAME) on the properties of polyols was investigated. Conversions of E‐FAME to PolyFAME polyols were confirmed by Fourier transform infrared analysis, oxirane oxygen content, and hydroxyl number. Gel permeation chromatography (GPC) calibrated against polyether polyols as a standard and vapor pressure osmometry were used for MW determination. GPC chromatograms of PolyFAME polyols clearly demonstrated the formation of oligomers during ring‐opening reactions. MW, and odd and even carbon numbers in a structure of linear diols and branched diol used in the syntheses of PolyFAME polyols did not have an effect on crystallinity, glass transition, or melt temperatures measured using Differential scanning calorimetry (DSC). PolyFAME polyols ring‐opened with water, methanol, and 1,2‐propanediol contained secondary hydroxyl groups, whereas PolyFAME polyols ring‐opened with linear diols contained a mixture of primary and secondary hydroxyl groups. It was found that the concentration of primary hydroxyl groups increased significantly by increasing the number of carbons from C2 to C3 in the linear diols. The viscosity of PolyFAME polyols also increased with the MW of linear diols used in the E‐FAME ring‐opening reaction. These findings would be beneficial for formulators in choosing the most cost effective polyols for polyurethane formulations.     

Polymerization of tetrahydrofuran initiated by heteropolyacid in the presence of substituted oxirane

Both propylene oxide and epichlorohydrin could effectively promote the polymerization of tetrahydrofuran initiated with a heteropolyacid, H₃PW₁₂O₄₀, in low concentration. Water or butylene glycol was used to control the molecular weight of the product in the range of 1000–3000. The promotion activity of propylene oxide was similar to that of ethylene oxide and better than that of epichlorohydrin, especially when water was introduced. The polymerization started upon addition of propylene oxide or epichlorohydrin. After the polymerization stopped, it could be reinitiated with the addition of a new portion of propylene oxide or epichlorohydrin. The products were found to be copolyether glycol with hydroxyl groups at both ends. The melting point of the polymer obtained by using propylene oxide promoter was about 20°C lower than that of polytetramethylene ether glycol having the same molecular weight. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3239–3246, 2000     

Synthesis of urethane oils from waste poly(ethylene terephthalate) bottles

Waste poly(ethylene terephthalate) (PET) bottles were glycolyzed by propylene glycol (PG) at a weight ratio of PET to PG of 37.5 : 62.5 using zinc acetate as a catalyst. The glycolyzed product, consisting of oligomeric diols with a number‐average molecular weight range of 458–844, was obtained. It was further reacted with soybean oil and toluene diisocyanate to obtain urethane oils at hydroxyl to isocyanate ratios from 1 : 1 to 1 : 0.7, with and without methanol acting as a blocking agent. All the synthesized urethane oils were yellowish, transparent, low‐viscosity liquids of low molecular weights. A lower diisocyanate content and the presence of a blocking agent resulted in higher viscosity, higher molecular weight, and shorter drying time. The films of all synthesized urethane oils exhibited good hardness and adhesion. They also showed excellent water and acid resistance but only fair alkali resistance. However, these prepared urethane oils had lower flexibility and poorer wear resistance compared to those of the commercial urethane oil. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3040–3045, 2004     

树枝状聚醚表面活性剂的合成与性质

以1.0G乙二胺为核的树状大分子聚酰胺-胺为起始剂,氢氧化钾为催化剂,分别与环氧丙烷(PO)、环氧乙烷(EO)反应合成了一系列二嵌段树枝状聚醚表面活性剂(DPE)。采用端基滴定法测定了产品的羟值,并根据理论结构计算出聚醚的相对分子质量;通过吊环法测定聚醚的表面张力,并探讨了化学结构对其性能的影响。结果表明这类具有新型化学结构的聚醚具有良好的表面活性,树枝状聚醚的表面活性随PO比率的提高而增强,而当聚醚的结构(EO/PO)相同时,相对分子质量对其表面活性的影响不大。     

Polymerization of ethylene oxide by the activated monomer mechanism

The Polymerization of ethylene oxide catalysed by protonic acids and proceeding via the activated monomer mechanism differs from the polymerizations of substituted epoxides like propylene oxide and epichlorohydrin. The kinetics of ethylene oxide polymerization were investigated and compared with the kinetics of model reactions, namely addition of oligomers of ethylene oxide to ethylene oxide. The mechanism of polymerization involves, besides the addition of monomer to the terminal hydroxyl groups, the addition to the polymer ether groups. This reaction does not take place for substituted oxiranes, most probably because of steric hindrance.     

Viscosity characteristics of aqueous solutions of block copolymers of propylene and ethylene oxides

Brookfield viscosity measurements were made on aqueous solutions of surface-active agents composed of block copolymers of propylene and ethylene oxides in which the molecular weights of the polymers varied from 1100 to over 15,000. The hydrophobia bases were polyoxypropylene glycols varying in molecular weight from 940 to 4000. To these were added varying amounts of ethylene oxide so that the polyoxyethylene hydrophil comprised from 15 to 80% of the surfactant total weight. This work has materially expanded previous viscosity studies of aqueous solutions of nonionic surfactants by using a unique type of hydrophobe, two ethylene oxide chains, and far higher molecular weights of hydrophobe and of hydrophil, up to 280 moles of ethylene oxide. The surface-active agents with hydrophobe base molecular weights from 940 to 1100, and in which the polyoxyethylene sections comprised from 15 to 80% of the total weight, did not form gels in aqueous solution. Some surfactants with a hydrophobe base molecular weight of 1750 to 2750, to which varying amounts of polyoxyethylene were added, formed gels in water at a surfactant concentration range of 40% to 80%. With a hydrophobe molecular weight of 3250, gels formed at from 30% to 90% surfactant concentration, while with one nonionic derived from a 4000 molecular weight hydrophobe, a gel formed at only 20% polyol concentration. Two viscosity maxima were found in some cases, as reported occasionally for other systems. An increase in temperature from 0C to 50C generally reduced the viscosity of systems based on hydrophobes of 1175 and lower molecular weights, and increased it in systems based on hydrophobes of 1750 and higher molecular weights. The behavior of these surfactants in forminggels is explained on the basis of hydrogen bonding, micellar aggregation and water entrapment. The moles of water per ethylene oxide group in the adduct varied with the hydrophobe base weight and with the polyoxyethylene hydrophil, and within systems showing maximum viscosities, ranged from 0.3 to 17.1, at 25C, which is much higher than observed in other nonionics.     

单官能度端伯,仲羟基聚丁二烯的研制

本文较详细地研究以ｎ－ＢｕＬｉ为引发剂，丁二烯为单体，抽余油为溶剂，四氢呋喃为１，２－结构调节剂，环氧乙烷和环氧丙烷为羟基化试剂，单官能度端伯、仲羟基聚丁二烯的合成。实验表明，丁羟胶的分子量为２０００～８０００可调；１，２－结构含量可控制在２５％以下，也可随意提高至４０％以上；分子量分布＜１．１，平均官能度接近１。此外，对所得样品采用ＶＰＯ、ＧＰＣ、ＩＲ、Ｈ’－ＮＭＲ等仪器和化学方法进行表征。     

Interphase Reaction of Isocyanates with Epoxy Resins Containing Functional Groups of Different Reactivity

Interphase reactions between cured epoxy resins and isocyanates are investigated. The epoxy resins contain secondary hydroxyl groups as reactive groups only or secondary hydroxyl plus amine. The isocyanate diffuses into the epoxy resin forming an interphase with a thickness of some micrometers. Depending on the functional groups available in the epoxy resin, urethane and urea groups are formed in the interphase. If a monofunctional isocyanate is used, no difference between both kinds of epoxy resin could be detected regarding the formation of urethane. If the epoxy resins react with bifunctional isocyanates a crosslinked interphase is formed. Due to the higher reactivity between amine and isocyanate compared to hydroxyl and isocyanate, the urea is formed first. The resulting cross‐links restrict the further diffusion of isocyanate into the epoxy resin. The consequence is a lower urethane content in the interphase and a thinner interphase compared to the epoxy resin containing hydroxyl only. If a prepolymer with isocyanate end groups is used as isocyanate the formation of the interphase is slower compared to the low molecular weight isocyanate. This is due to the reduced mobility of the prepolymer.     

Novel initiators for the synthesis of propylene oxide oligomers by anionic ring opening polymerization

A series of potassium alcoholates was obtained from the reaction between KOH and ethylene glycol, resorcinol, 4,4′-bisphenol A, 4,4′-(1,3 phenylenediisopropylidene)-bisphenol, 4,4′-sulfonyldiphenol. These salts were employed to initiate the anionic ring opening polymerization of propylene oxide (PO). The molecular weight distribution of the propylene oxide oligomers prepared by this method and the initiator structure were correlated. These oligomers were characterized through Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR) spectroscopies and size exclusion chromatography (SEC). It was found that the molecular weight and polydispersity of the synthesized poly(propylene oxide) (PPO) is highly dependant on the initiator structure and solubility in the reactive medium. The oligomers obtained using di-potassium resorcinolate exhibited a molecular weight distribution more polydisperse than that of PO oligomers synthesized by means of di-potassium ethylene glycolate. In the case of the PO polymerizations started by the potassium salts of 4,4′-bisphenol A, 4,4′-(1,3 phenylenediisopropylidene)-bisphenol and 4,4′-sulfonyldiphenol, the oligomer chains showed very broad molecular weight distributions. In general, lower solubility and augmentation of the polymer polydispersity were observed when the number of aromatic rings in the initiator structure increased. The experimental results were contrasted with those obtained from quantum chemical semiempirical calculations at AM1 level. The peculiar behavior exhibited by the initiators with an aromatic structure could be explained in terms of different reactivities of the initiation sites. The theoretical studies revealed that the ring in the aromatic initiators promotes an unsymmetrical growing when the PPO chains are formed. In contrast, the identical reactivity of both initiation sites in the ethylene glycolate produces a symmetrical growing during the PO polymerization.     

Unsaturated polyesters from PET waste: Kinetics of polycondensation

PET waste was glycolyzed by propylene glycol at different weight ratios. The glycolyzed products were analyzed for hydroxyl value, number average molecular weight, and the amount of free glycol. The glycolyzed products were reacted with maleic anhydride at a hydroxyl to carboxyl ratio of 1.1. The control resin was a general purpose unsaturated polyester prepared by reacting phthalic anhydride, maleic anhydride, and propylene glycol. The heating schedule of the polyesterification was comparable to that normally employed in the industrial process, with two isothermal plateau of 3–4 h at 180 and 200°C. The rate of reactions and rate constants were determined separately at 180 and 200°C. The kinetics of the PET-based unsaturated polyesters was compared with that of the general purpose resin. It was found that the PET waste could be depolymerized by propylene glycol to a molecular weight range of 276–480. The polyesterification reactions followed a third-order kinetics. The rates of polyesterification of PET based systems were higher than that of the general purpose resin. PET-based systems were higher than that of the general purpose resin. PET-based systems took about 10 h to reach an acid value of 32 mg KOH/g whereas the general purpose resin took about 25 h to reach the same acid value.     

大气压离子化质谱技术研究N-聚氧乙烯醚衍生物

利用大气压离子化质谱技术 ,采用直接进样方式研究了N 聚氧乙烯醚衍生物的氧乙烯链聚合度 (EO数 )分布 ,并对O 聚氧乙烯醚衍生物及壬基酚聚氧乙烯醚进行了测定。当化合物的分子质量小于 1 0 0 0u时 ,采用大气压化学离子源和大气压电喷雾离子源两种离子化质谱技术均可得到正态的EO数分布曲线 ,最大n值与根据环氧乙烷加入量计算出的平均加成数基本吻合。采用直接进样质谱技术可同步分析含氧乙烯链的不同结构化合物的EO数分布曲线。选择大气压化学离子源检测时 ,样品与溶剂间的极性差异越小越好 ;而采用大气压电喷雾离子源时 ,溶剂极性对EO数的正态分布影响较小。对于EO数较大的化合物 ,宜采用大气压电喷雾源离子化 ,并可观察到多电荷体系 ;调节质谱参数将影响多电荷体系的分布。直接进样质谱技术为含氧乙烯链化合物的EO数分布提供了一条快速、简捷的分析途径。