应用激光解吸电离飞行时间质谱法研究芳香聚硫醚醚砜环状低聚物

应用激光解吸电离飞行时间质谱法对芳香环状聚硫醚醚砜低聚物结构进行了分析,比较了四种不同基质对环状物结构分析结果的影响,发现1,8,9-蒽三酚为此类芳香环状低聚物的有效基质。探讨了金属阳离子对此类芳香环状低聚物的影响,认为三氟乙酸银是此种芳香环状低聚物的有效阳离子剂。     

芳香环状低聚物组分分布与单体结构关系的研究

根据Jacoson-Stockmayer(J-S)环化理论,应用基质辅助激光解吸离子化飞行时间质谱(MAIDL-TOFMS),对一系列芳香环状低聚物组分分布进行分析,研究了芳香环状低聚物的组分分布与单体结构的关系,结果表明,在芳香聚酯、聚膦酸酯及芳香聚醚环状低聚物系列中,Incn与Inn呈良好的线性关系,符合J-S理论分布,在环状聚酯及聚膦酸酯系列中,低聚物的组分分布受双酚单体的中心键角影响,单体的中心键角在100°～120°之间,其中心键角愈小,γ值愈大,而在聚醚系列中,在固定一种单体的前提下,环化物的组分分布受另一单体键角的影响与环状聚酯和聚膦酸酯相一致.     

MALDI-TOFMS表征均聚芳香硫酚环状低聚物

采用基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)对4种合成的均聚芳香硫酚环状低聚物进行了质谱表征;并且对4种合成产物的组成、结构进行了分析及确认;得到了均聚芳香硫酚环状低聚物的相对分子质量及其分布信息;研究结果显示：MALDI-TOF MS是分析均聚芳香硫酚环状低聚物的有效工具。     

芳香环状聚酯二聚体的结构表征

通过基质辅助激光解析电离飞行时间质谱以及核磁共振技术对芳香环状聚酯二聚体的结构进行了表征.质谱分析结果发现除了目标化合物的质子化分子离子峰外,未出现更多的碎片峰,而核磁共振结果对芳香环状齐聚物的氢以及碳的位置给予了确认.从而为芳香环状齐聚物的结构分析提供了一种新的分析方法.     

基质辅助激光解吸电离-飞行时间质谱表征6氟双酚A芳香环状聚醚酮(砜)

应用基质辅助激光解吸电离飞行时间质谱,在不同阳离子剂的存在下,对6氟双酚A聚芳醚酮(砜)环状低聚物的结构进行了确认,研究了环状化合物对金属离子的选择性及激光质谱表征含氟环状低聚物的适宜条件.     

基质辅助激光解吸电离—飞行时间质谱表征6氟双酚A芳香环状聚醚酮（砜）

应用基质辅助激光解吸电离飞行时间质谱,在不同阳离子剂的存在下,对６氟双酚Ａ聚芳醚酮（砜）环状低聚物的结构进行了确认,研究了环状化合物对金属离子的选择性及激光质谱表征含氟环状低聚物的适宜条件。     

含酚酞结构的聚芳醚酮环状齐聚物的激光质谱表征

在“拟高稀”条件下，以酚酞与甲基酚酞为双羟基型单体，与活性双氟基芳香化合物合成了聚芳醚酮环状齐聚物。通过基质辅助激光解吸电离飞行时间质谱对其环状结构进行了表征。     

用MALDI-TOF-MS法表征系列环状预聚体

应用基质辅助激光解吸电离飞行时间质谱（MALDI－TOF－MS）技术对系列环状预聚体进行了表征,分别确定了系列环状预聚体各自不同的聚合度,同时对它们的结构进行了确认,获得了满意的结果。实验结果表明MALDI－TOF－MS是分析环状预聚体准确、快速工具之一。     

基质辅助激光解吸电离飞行时间质谱对环状芳香多硫寡聚物的研究

采用基质辅助激光解吸电离飞行时间质谱(MALDI TOF-MS)对环状芳香硫醚的寡聚产物进行了测定和分析,首次确定了这类采用其它传统方法难以分析的难溶多硫环状芳香硫醚寡聚物的结构;研究了芳香烃部分随聚合度不同的分布规律和芳香烃部分相同的条件下S原子数目不同而引起的组分变化的规律;讨论了4种基质的辅助解吸电离效果和离子化试剂对测定结果的影响,探索出测定这类寡聚物的最佳条件.     

单分散的还原态和中间氧化态聚苯胺齐聚物的合成与紫外光谱研究

提出了一条合成苯胺齐聚物的新路线:由高氧化态的苯胺四聚体与二苯胺或N-苯基-1,4-对苯二胺反应合成苯基封端的苯胺五聚体和六聚体,用红外、质谱、核磁共振、基底辅助激光解吸质谱(MALDI-MS)进行了表征.提出一条可能的机理,即高氧化态的苯胺四聚体与二苯胺或N-苯基-1,4-对苯二胺在酸性溶液中混合时,四聚体、二苯胺和N-苯基-1,4-对苯二胺的分子中均形成阳离子自由基,四聚体的阳离子自由基与后二者的阳离子自由基耦合形成苯胺五聚体和六聚体.还原态的苯胺齐聚物氧化成中间氧化态的苯胺齐聚物,使用硫酸铵和六水和三氯化铁等氧化剂能打断苯胺五聚体和六聚体的分子链.实验发现,氧化银是将还原态苯胺齐聚物氧化成中间氧化态的齐聚物的最好的氧化剂.用紫外可见光谱对中间氧化态的五聚体和六聚体进行了研究,对其分子中醌环的数目进行了讨论.     

SYNTHESIS, CHARACTERIZATION AND RING-OPENING POLYMERIZATION OF CYCLIC (ARYLENE PHOSPHONATE) OLIGOMERS

INTRODUCTIONThe use of cyclic oligomers as macrocyclic precursors for the preparation of high performance polymers byring-opening polymerization (ROP) has sparked much interest in recent years. It could produce a revolutionarychange in the preparation of advanced composite materials, and is of great importance in the polymerizationprocess yielding polymers such as the reinforced reactive injection model (RRIM) and the resin transfer model(RTM) etc. Within the last 10 years, the synthes…     

Lipase-catalyzed transformation of poly(lactic acid) into cyclic oligomers

Enzymatic transformations into cyclic oligomers were carried out with the objective of developing chemical recycling of poly(lactic acid)s, such as poly(D,L-lactic acid) (PDLLA), poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA), which are typical biodegradable polymers. They were degraded by lipase in an organic solvent to produce the corresponding cyclic oligomer with a molecular weight of several hundreds. PDLLA (with a Mw of 84,000) was quantitatively transformed into cyclic oligomers by lipase RM (Lipozyme RM IM) in chloroform/hexane at 60 degrees C. PLLA (with a Mw of 120,000) was transformed into cyclic oligomer by lipase CA (Novozym 435) at a higher temperature of 100 degrees C in o-xylene. The oligomer structure was identified by 1H and 13C NMR spectroscopy and MALDI-TOF (matrix assisted laser desorption/ionization-time-of-flight) mass spectrometry.     

MALDI-TOF质谱表征聚芳醚酮环状低聚物及其组分分布

应用介质辅助激光解吸离子化飞行时间质谱(MALDI-TOFMS),以二羟基苯甲酸为介质、N₂(337nm)为激光源,对两种聚芳醚酮环状低聚物的结构进行了确认,研究了环状低聚物不同聚合度组分的分布规律,并且与GPC质量分析法作了比较,实验结果表明,MALDI-TQF质谱是分析环状低聚物的准确、快速的工具之一.     

Cyclo-depolymerization of poly(propylene terephthalate): some ring-opening polymerizations of the cyclic oligomers produced

We report the cyclo-depolymerization of poly(propylene terephthalate) to give a mixture of cyclic oligomers in 94% yield, the characterization of the mixture by ¹H-NMR spectroscopy, matrix assisted laser desorption ionization time of flight mass spectrometry and gel permeation chromatography. The major cyclic oligomer in the mixture was shown to be the cyclic dimer. It was isolated and its X-ray crystal structure determined. Some entropically-driven ring-opening polymerizations of the cyclic oligomers were carried out. So too were some copolymerizations using mixtures of the cyclic oligomers and those derived similarly from poly(ethylene terephthalate) and poly(butylene terephthalate). ¹³C-NMR spectroscopic analysis showed that the copolymers were random. Copyright © 2003 John Wiley & Sons, Ltd.     

Short carbon fiber reinforced aromatic polydisulfide derived from cyclic (4,4′‐oxybis(benzene)disulfide) via ring‐opening polymerization

Morphology, mechanical and thermal properties of short carbon fiber reinforced poly(arylene disulfide) synthesized by ring‐opening reaction of cyclic(arylene disulfide) oligomers were studied. These macrocyclic oligomers were prepared from 4,4′‐oxybis(benzenethiol) by oxidation coupling cyclization. Ring‐opening polymerization (ROP) was carried out by in situ melt molding in air. Oxidation reaction during the ROP was detected using the Raman spectrum technique. Three‐point bending tests were performed to determine the flexural properties of neat polymers and the composites. The results showed that the flexural strength and modulus of poly(arylene disulfide)/carbon fiber composites were greatly enhanced with the carbon fiber addition. The maximum weight loss peak temperatures of the composites increased with increasing short carbon fiber content. Good adhesion between carbon fiber and the matrix was observed using scanning electron microscopy (SEM) technique. Copyright © 2005 John Wiley & Sons, Ltd.     

Cyclic(arylene ether) oligomers containing the phenylphosphine oxide moiety

A series of cyclic(arylene ether) oligomers containing the phenylphosphine oxide moiety has been synthesized by reaction of bis(4-fluorophenyl)phenylphosphineoxide with dihydroxy compounds 1a–d as well as 1,2-dihydro-4-(4-hydroxyphenyl) (2H)phthalazin-1-one in DMF in the presence of anhydrous K₂CO₃ under high dilution conditions. These cyclic oligomers are amorphous and have high solubility in organic solvents. The MALDI-TOF-MS technique has been used as a powerful tool to analyze these cyclic systems. The cyclic(arylene ether) oligomers readily undergo anionic ring-opening polymerization in the melt at 350°C by using potassium 4,4′-biphenoxide as the initiator, affording linear, high molecular weight poly(arylene ether)s containing the phenylphosphine oxide moiety. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 519–526, 1998     

Synthesis and ring‐opening polymerization of macrocyclic (arylene thioether ketone) oligomers

Macrocyclic (arylene thioether ketone) oligomers together with a linear poly(phenylene sulfide ketone) oligomer were synthesized by a one‐step reaction. The macrocycles and linear oligomer were fully characterized by ¹³C‐NMR, H‐NMR, matrix assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS), differential scanning calorimetry (DSC) and FT‐IR. Uncatalyzed, simultaneously ring‐opening polymerization (ROP) of the macrocycles and the mixture of macrocycles and linear oligomer were carried out under dynamic heating conditions. The ROP temperature of the macrocycles decreased upon mixing it with the linear oligomer. The ROP conditions and mechanism were investigated and discussed. The macrocycles and their mixture show potential applications in high temperature adhesives and sealants. Copyright © 2006 John Wiley & Sons, Ltd.     

Isolation and identification of the linear and cyclic oligomers of poly(ethylene terephthalate) and the mechanism of cyclic oligomer formation

Chromatographic techniques are described which can be used to isolate and identify the linear and the cyclic oligomers of poly(ethylene terephthalate). Extraction of the oligomers from high molecular weight polymer produces at least eight different cyclic species, some of which are isolated and identified. The cyclic dimer, the cyclic trimer, and the cyclic tetramer of poly(ethylene terephthalate) have also been prepared by acid chloride esterification and transesterification. Similar materials can be isolated from the ethylene glycol distillate obtained from the polymer melt. The mechanism of cyclic oligomer formation has been studied by determining the rate of formation of the cyclic oligomers during polymerization and during melt extrusion of polyesters which did not initially contain cyclic oligomers. The rate of formation depends upon the concentration of hydroxyl groups; hence, the cyclic oligomers are formed by transesterification from the chain ends or cyclodepolymerization. Therefore oligomers are inevitably produced during polymerization.