窄分布脂肪醇聚氧乙烯醚的合成研究

在KOH和窄分布专用均相催化剂作用下,分别合成了2种不同平均EO加合度的AEO。根据合成过程中EO的消耗量计算得到理论平均EO加合度,气相色谱法分析了产品组成分布,对常规及窄分布AEO的EO分布、平均EO加合度对分子量分布的影响等进行了研究。结果表明,窄分布AEO气相色谱图中C_(12)(EO)_7的峰面积很小,基本看不到C_(14)(EO)_7的峰;对于常规及窄分布AEO,AEO2组分中游离脂肪醇质量分数低于AEO_(1.85),EO加合度为1～4组分的总质量分数则高于AEO1.85;窄分布AEO组分中游离脂肪醇和EO加合度大于4组分的质量分数明显低于常规AEO,而EO加合度为1～4组分的质量分数明显高于常规AEO,分子量分布呈泊松分布,表现出明显的窄分布特点。     

Synthesis of hydroxy-terminated polytetrahydrofuran by photoinduced process

Summary This paper describes the preparation of hydroxy-functional telechelics by photoinduced decomposition of polytetrahydrofuran possessing terminal pyridinium ions in THF solution. Hydroxyl functionality was evidenced by end capping and polycondensation with isocyanates.     

新型聚四氢呋喃多元醇的合成及表征

以丙三醇或水为共引发剂,三氟化硼乙醚（BF₃·OEt₂）为引发剂,引发四氢呋喃阳离子开环聚合,合成了一种新型聚四氢呋喃三元醇（PTHF-T）及聚四氢呋喃二元醇（PTMG/PTHF-D）。研究了丙三醇、丙三醇/水、水、反应时间等对聚合反应的影响。用傅里叶变换红外光谱法（FTIR）表征PTHF结构,凝胶渗透色谱法（GPC）、黏度法测定分子量,端基滴定法测定羟值。结果表明,不同丙三醇/水比例,可定量获得不同官能度的聚四氢呋喃多元醇（PTHF）;丙三醇为共引发剂能得到产率高且分子量分布窄的PTHF;同时得出PTHF重均分子量M_w与黏均分子量M_h的关系式。该PTHF-T可用于聚氨酯快速吸附材料的制备。     

Synthesis and reactions of polytetrahydrofuran with thiolanium end groups

Living polytetrahydrofuran can be terminated with thiolane to form the corresponding thiolanium-terminated polymers. The thus obtained monotelechelic or ditelechelic polymers are unreactive towards water, but can selectively couple with charged nucleophiles by a nucleophilic ring-opening reaction of the terminal thiolanium ions. This process has been used to prepare well-defined homopolymers such as star polymers, segmented polymers or model networks.     

窄分布低分子质量端羟基聚四氢呋喃的合成与研究

以三氟化硼乙醚配合物(BF3·OEt2)为催化剂,环氧丙烷(PO)为起始剂,二氯甲烷(CH2 Cl2)作溶剂,通过四氢呋喃的阳离子开环聚合合成了窄分子质量分布(Mw/Mn＜1.3)的端羟基聚四氧呋喃(PTHF).研究了三氟化硼乙醚配合物用量、溶剂用量、起始剂用量、反应时间对PTHF分子质量(Mn)及其分布(Mw/Mn)...     

Synthesis of silicon nanoparticles with a narrow size distribution: A theoretical study

This work presents a study of the processes involved in synthesis of narrowly distributed silicon nanoparticles from the thermal decomposition of silane. Two models are proposed, one which simultaneously solves the kinetic mechanism of Swihart & Girshick (1999, Journal of Physical Chemistry B 103, 64–76) while adjusting the sintering parameters; and another which adjusts the kinetic and surface growth mechanisms while neglecting coagulation and sintering. The models are applied to simulate the centreline of the hot-wall reactor and process conditions of Körmer et al. (2010, Journal of Aerosol Science 41, 998–1007). Both models are shown to give good agreement with experimental PSDs at a range of process conditions. However, it is reported that an unphysical sintering process is obtained when attempting to use Swihart & Girshick's kinetic mechanism, while solving for the sintering parameters. The model with adjusted gas-phase and surface growth processes gives better quantitative and qualitative agreement with experimental results. It is therefore recommended that further study into the kinetic and heterogeneous growth mechanisms be conducted in order to better understand the fundamental processes occurring in this hot-wall reactor.     

窄分子量分布端羟基环氧乙烷-四氢呋喃共聚醚的合成及表征

用三氟化硼乙醚络合物(BF3.OEt2)为催化剂,乙二醇(EG)为起始剂,甲苯作溶剂,通过阳离子开环聚合制备出了窄分子量分布(w/n<1.3)的端羟基环氧乙烷-四氢呋喃(TEO)共聚醚,探讨了聚合温度、时间、反应介质、加料方式、起始剂及单体配比对分子量及其分布的影响,采用凝胶渗透色谱-多角度激光散射联用仪(SEC-MALLS)对其分子量及分布进行准确的测定,并用IR和1HNMR对共聚醚结构进行了表征。研究表明:有EG存在时,采用一次加料的方式,以甲苯为溶剂,温度为0℃,单体配比为11,∶反应时间为5 h的条件下制得的共聚醚具有分子量分布较窄的特点。     

聚四氢呋喃合成催化剂研究进展

论述了近期文献报导的能催化四氢呋喃开环聚合的各类催化体系, 并对不同催化体系的优缺点进行了评述。     

Synthesis and characterization of air‐stable magnetic Fe composites microspheres of narrow size distribution

Air‐stable Fe magnetic nanoparticles entrapped within carbon and porous crosslinked polystyrene microspheres of narrow size distribution were prepared by the following sequential steps: (1) Polystyrene/poly(divinyl benzene) and polystyrene/poly(styrene‐divinyl benzene) uniform micrometer‐sized composite particles were prepared by a single‐step swelling of uniform polystyrene template microspheres dispersed in an aqueous continuous phase with emulsion droplets of dibutyl phthalate containing the monomers divinyl benzene and styrene and the initiator benzoyl peroxide. The monomers within the swollen polystyrene template microspheres were then polymerized by raising the temperature to 73°C; (2) Porous poly (divinyl benzene) and poly(styrene‐divinyl benzene) uniform crosslinked microspheres were prepared by dissolution of the polystyrene template part of the former composite particles; (3) Uniform magnetic poly(divinyl benzene)/Fe and poly(styrene‐divinyl benzene)/Fe composite microspheres were prepared by entrapping Fe(CO)₅ within the porous crosslinked microspheres, by suction of the Fe complex into the dried porous particles, followed by decomposition of the encapsulated Fe(CO)₅ at 200°C in Ar atmosphere; (4) Uniform magnetic air‐stable C/Fe composite microspheres were prepared similarly, apart from changing the decomposition temperature from 200 to 600°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Conducting copolymers of polypyrrole/polytetrahydrofuran

Summary Bifunctional living polytetrahydrofuran (PTHF) was terminated with potassium salt of pyrrole to yield polymers with electrochemically active end groups. These polymers were employed in the second stage to obtain conducting polypyrrole/polytetrahydrofuran block copolymers with short and long polytetrahydrofuran segments by potentiostatic anodic polymerization of pyrrole in different electrolytic media. Syntheses of block copolymers were achieved in media where tetrabutylammonium fluoroborate, sodium perchlorate and sodium p-toluenesulfonate were used as the supporting electrolytes. Characterizations were based on DSC, TGA, SEM, FTIR, and CV analyses. No significant effect of the chain length of polytetrahydrofuran segments on the properties of the copolymers was observed; however, thermal, electrochemical behaviors, and surface morphologies of the films were greatly affected by the supporting electrolytes. Received: 5 January 1998/Revised version: 25 March 1998/Accepted: 27 March 1998     

均相钕系催化剂合成窄相对分子质量分布的高顺式-1，4-聚丁二烯

考察了由Nd(vers),(简称Nd)、Al(i-Bu)2H(简称Al)争Al(i-Bu)2Cl(简称Cl)组成的均相催化剂体系在5L釜中于70℃聚合丁二烯的反应规律,并在2m3装置上进行了放大试验.结果表明,该均相钕系催化剂具有高的稳定性;Al/Nd(摩尔比)是影响相对分子质量分布的重要因素,当Al/Nd低于20时,产物的相对分子质量分布在3.00以下;改变Nd/Bd(摩尔比)或使用不同组成的Al,可改变聚合产物的门尼黏度,但对相对分子质量分布无明显影响.在2m3装置上,采用均相钕系催化荆可以得到收率大于90%、相对分子质量分布小于3.00和顺式-1,4-结构摩尔分敷大于97.0%的聚丁二烯.     

用均相钕系催化剂合成具有窄相对分子质量分布的顺式-1,4-聚丁二烯

在丁二烯存在及50℃下,使钕系化合物,如新癸酸钕、异辛酸钕以及异辛酸改性的膦酸钕与Al（i-Bu）2H反应,再与Al（i-Bu）2Cl作用,可形成均相稳定的钕系催化剂体系。结果表明,该催化剂不仅对丁二烯聚合具有高的催化活性及立体定向性（顺式-1,4-结构质量分数大于96％）,而且具有单一活性中心的特征,可合成相对分子质量分布指数接近于2．00的聚丁二烯。     

Cohesive energy density of polytetrahydrofuran

Measurements have been conducted on radiation-crosslinked polytetrahydrofuran (PTHF) of stress-strain and of swelling coefficients in simple esters. For the linear polymer, measurements have been made of density and intrinsic viscosities in the esters. [η] was also determined under the θ conditions of 33.5°C. in diethyl malonate. The results have been incorporated into several (sometimes interdependent) approaches towards the evaluation of the solubility parameter δ_p of PTHF. The mean of the nine values obtained is 8.55 (cal./cc.)^1/2, whence the cohesive energy density is 5.17 kcal./mole. Seventeen experimental values of the Flory interaction parameter χ are also reported.     

Effect of chain length distribution on thermal characteristics of model polytetrahydrofuran (PTHF) networks

A series of model polytetrahydrofuran (PTHF) networks were synthesized via end-linking reactions of α, ω-allyl PTHF oligomers with a stoichiometric tetrafunctional crosslinker. The telechelic PTHF oligomers were synthesized by living cationic ring-opening polymerization of tetrahydrofuran followed by a termination reaction with allyl alcohol. Networks thus prepared have well-controlled architecture in terms of the inter-crosslink chain length (M_c) and chain length distribution: resulting in unimodal, bimodal and clustered structures. Unimodal network was prepared by using polymer chains of same molecular weight, bimodal networks were synthesized by using two groups of polymer chains with different average molecular weights, and the clusters are prepared by incorporating clusters of networks with small molecular weight chains in a network matrix made of longer chains. Thermal characteristics of these model networks were investigated as a function of crosslink density, as well as inhomogeneities of crosslink distribution using DSC. We demonstrate that glass transition temperature (T_g) and crystallization behavior (melting temperature and crystallinity) of the networks are both strongly influenced by crosslink density (M_c). By comparing the unimodal, bimodal and clustered networks with similar average M_c, the effects of inhomogeneities in the crosslink distribution on the thermal properties were also investigated. Results show that inhomogeneities have trivial influence on T_g, but strongly affects the crystallization behavior. Moreover, the effects of the content ratio and length ratio between long and short chains, and the effects of cluster size and size distribution on the thermal characteristics were also studied.     

High ethoxylated alcohols with narrow distribution of homologues

Homologue distributions of alcohol ethoxylates obtained with an unconventional calcium-based catalyst and NaOH as the conventional catalyst are studied in the range of average polyaddition degree from 8 to 15. The fractional compositions of those high molecular weight derivatives of dodecanol and other technical alcohols, Lial 125 and Radianol 1724, are determined as peak area percentages from HPLC chromatograms. Some physico-chemical characteristics of the products as well as by-product contents are also presented. It is shown that the differences in fractional contents between the broad and narrow homologue distributed equivalents remain very significant in that range of higher ethoxylation grades. Consequently, the influence of homologue distributions on some properties of the products can be expected in their practical applications.     

Diffusion in dilute polytetrahydrofuran solution

The diffusion coefficients of four polymer-solvent mixtures at 34.0‡C were measured using a Mach-Zehnder diffusiometer. Monodisperse (M_w/M_n <1.05) polytetrahydrofuran (PTHF) with and without OH-end group were chosen for this work to study the effects of association of polymer molecules on the diffusion coefficient. In order to minimize the interaction between solvent and polymer molecules, bromobenzene having no hydrogen bond-forming capability was employed as a solvent. The experimental results showed that the OH end group indeed affected diffusion property of dilute polymer solution. An association model was developed in this work and the experimental results were interpreted based on the model.     

窄分布聚醚合成用催化剂的研究

研究了不同碱催化剂催化合成聚氧乙烯(PEG)与聚氧乙烯-丙烯共聚醚(PEPG)的反应,考察了镁铝复合氧化物的制备条件对催化性能的影响,通过凝胶色谱仪(GPC)对产品分子量及分布情况进行了分析。结果表明,催化制备聚氧乙烯研究中,以KOH、镁铝复合氧化物的催化效果较好;催化制备氧化乙烯-氧化丙烯共聚醚研究中,以NaOH、镁铝复合氧化物的催化效果较好;制备镁铝复合氧化物催化剂时,当以Na2CO3,NaOH为共沉淀剂,镁铝物质的量比3∶1,煅烧温度550℃时,制备的镁铝复合氧化物催化剂催化性能最佳。     

聚四氢呋喃催化合成研究进展

主要论述和归纳了目前文献报道的能够催化四氢呋喃开环聚合的各类催化体系,并对不同催化体系的优缺点进行了评述     

Poly(acrylonitrile) microspheres with a narrow size distribution: Synthesis by single-step swelling and properties

Poly(acrylonitrile)-poly(styrene) micrometer-sized composite particles with a narrow size distribution are prepared by single-step swelling of poly(styrene) uniform template microspheres in emulsion droplets of methylene chloride containing an acrylonitrile monomer and a benzoyl peroxide initiator. Methylene chloride is carefully evaporated with subsequent polymerization of acrylonitrile at a temperature of 70°C inside the shrunken template particles. Acrylonitrile is also polymerized at the particle surface due to the interaction of surface poly(acrylonitrile) oligoradicals with acrylonitrile dissolved in the aqueous phase. Uniform poly(acrylonitrile) particles with a larger surface area are formed by dissolving template poly(styrene) of the composite particles. The surface and bulk properties of the particles are investigated using Fourier transform IR (FTIR) spectroscopy, elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction, X-ray photoelectron spectroscopy (XPS), contact-angle measurements, optical microscopy, scanning electron microscopy (SEM), and cross-sectional transmission electron microscopy (TEM).Original Russian Text Copyright © 2005 by Fizika i Khimiya Stekla, Boguslavsky, Margel.