含硫醚结构均苯型聚酰亚胺的合成及表征

以4,4′-二氨基二苯硫醚(SDA)和均苯四酸酐(PMDA)为原料,通过溶液缩聚法-热酰亚胺/化学酰亚胺化的方法制备了一种含硫醚结构均苯型聚酰亚胺.利用高级旋转流变仪建立了在线跟踪反应进程的方法,采用热失重分析仪研究反应条件对热酰亚胺化及化学酰亚胺化法的影响,这些方法的建立为进一步制备高性能的聚酰亚胺提供有效的实验手段.采用小角激光光散射法、红外光谱、元素分析、接触角仪、DSC等方法对聚合物的结构与性能进行表征.结果显示,硫醚结构的引入,可有效改善聚合物薄膜的表面性能,其与铜箔之间的粘附功明显大于传统聚酰亚胺,在无胶挠性线路板应用方面显示出较好的应用前景.所获聚合物的Mw为(6.7±1.6)×104,分解温度均高于560℃;DSC的结果显示所制备的两种酰亚胺化聚合物均具有较高的玻璃化转变温度,相比之下,化学酰亚胺化更有利于获得高酰亚胺化程度的聚合物,产物的玻璃化转变温度也更高.     

Cu(0)/Selectfluor体系催化的邻芳基磺酰亚胺的串联环化/芳构化反应：一种简便合成6H-菲啶的方法（英文）

发展了Cu(0)/Selectfluor体系催化的邻芳基磺酰亚胺的串联环化/芳构化反应,于温和的反应条件下以中等到良好的产率简便、高效地构建了一系列6H-菲啶类化合物.机理研究表明,反应的关键步骤经历了由Cu(0)/Selectfluor体系现场原位产生XCuOH (X=F, BF4)物种,进而诱导对C=N键的羟铜化反应和分子内C—H键胺化反应,从而合成了6H-菲啶类化合物.     

长链聚酰胺酸的热环化动力学

利用GPC、原位FTIR测定了长链聚酰胺酸PAA(由双酚A二酐与 4 ,4′ 二 (4 胺基苯氧基 )二苯酚制备 )的热环化过程 .结果表明 ,在升温热环化的初始阶段 ,聚合物环化的同时其分子链断裂成酐、胺端基分子链 ,相对数均分子量降低 ,薄膜渐脆 ;随着温度进一步的升高 ,酐、胺端基链又重新链合 ,相对数均分子量回升 ,薄膜重具韧性 ;恒温热环化存在两个明显的阶段 ,初期的快速阶段和后期的慢速阶段 ,表现出动力学中断的现象 .采用两步、一级动力学模型研究热环化并得出相关的动力学参数 (速率常数、活化能、指前因子等 ) .针对恒温热环化 ,建立动力学中断时亚胺化程度与温度的关联式 ,从构象转化与自由体积两个方面对动力学中断现象提出解释 ,并由实验数据得到了该关联式的相关参数     

聚苯并双噁唑酰亚胺的热分解动力学研究

采用二步法合成了以2,6-二(对-氨基苯)苯[1,2-d;5,4-d’]二噁唑和1,4-二(3,4-二苯氧基)苯四甲酸二酐(HQDPA)为单体的聚苯并双噁唑酰亚胺.该聚酰亚胺的预聚体聚酰胺酸的黏度为1.70 dL/g,经过热环化后能够生成浅黄色的聚酰亚胺薄膜.通过热重分析法研究了聚苯并双噁唑酰亚胺在N2气氛中的热降解机理.采用Flynn-Wall-Ozawa和Friedman法计算了聚苯并双噁唑酰亚胺热降解表观活化能,分别为356.36kJ/mol和370.54 kJ/mol,平均值为363.45 kJ/mol;反应级数为4.22,指前因子为6.44×1016s-1.采用Coast-Redfern法和Phadnis-Deshpande法研究了聚苯并双噁唑酰亚胺的热降解固相反应机理,认为该聚酰亚胺的热降解机理属于反曲线(A3)机理,是成核和增长模式(Avrami equation 2方程)控制的热降解反应,积分形式为g(X)=[-ln(1-X)]3.     

二氧化碳参与的环化反应最新研究进展

二氧化碳是一种储量丰富且廉价易得的可再生碳一资源.将二氧化碳高效转化成高附加值化学品的有机合成方法学研究目前已经成为最为活跃的研究方向之一.由于环化反应种类的多样性以及环化产物在众多生物活性分子结构中的广谱性,二氧化碳参与的环化反应也深受广大研究者重视.综述了最近二氧化碳参与的环化新反应合成内酰胺、内酯、邻苯二甲酰亚胺、环状酸酐、苯并噻唑及苯并咪唑等杂环化合物,同时也介绍了一些二氧化碳作为反应底物但不参与成环过程合成环状羧酸的新反应.     

(±)-茶螺烷酮的合成

在超声辐射下,β-环柠檬醛与丙酮经加成反应制得中间体3;3经硼氢化钠还原、硫酸氢钾催化脱水环化、N-羟基邻苯二甲酰亚胺/乙酰丙酮亚钴(Ⅱ)[NHPI/Co(acac)2]催化氧化烯丙位碳合成了(±)-茶螺烷酮,总收率54.5%,其结构经1HNMR,IR,MS和元素分析表征。     

单向拉伸聚酰亚胺薄膜

分别以聚酰胺酸法和部分酰亚胺化的“凝胶法”研究了均苯二酐/二苯醚二胺(PMDA/ODA)和联苯二酐/对苯二胺(BPDA/PPD)体系聚酰亚胺薄膜在制膜过程中对单向拉伸比的影响,研究了薄膜在热膨胀系数和力学性能方面的差别。结果表明,“凝胶法”薄膜可以有较高的拉伸比,可以使薄膜有较低的热膨胀系数(对于PMDA/ODA,由35.1×10-6/℃降低到12.5×10-6/℃),可以明显提高拉伸方向的强度和模量,PMDA/ODA可以分别达到236MPa和1.7GPa;BPDA/PPD可以分别达到613MPa和9.3GPa,但伸长率有所降低。     

改性八面沸石上结炭的红外光谱研究——Ⅳ.骨架硅铝比对结炭的影响

随着Si/Al比的增加,1-已烯逐渐与小笼羟基发生作用,至Si/Al为8.87时,可完全作用,这与吡啶吸附实验结果一致。低Si/Al比时,1-已烯可与部分剩余超笼羟基作用形成“氢键”,在约3300cm~(-1)产生吸收谱带;在高Si/Al比时,1-已烯亦可与硅终端羟基作用,使其伸缩振动谱带发生位移,在3700cm~(-1)处产生红外吸收。结炭过程中,1-已烯首先脱氢、环化形成低环芳烃,并进一步发生加成、环化反应;到结炭反应后期,环缩合、氢转移和支链化反应加强,使焦炭发生“老化”,具有了多支链、贫氢、多环芳烃的性质。随着Si/Al比的增加,结炭反应变缓,饱和结炭量减少,焦炭的“老化”程度降低。     

耐高温高塑性应变高聚物及其酰亚胺化特征

本文介绍了最近研制成功并用于材料热强度应变测量、耐热300℃、灵敏系数K>1.85和应变极限ε>8％,具有独特力学性能的耐高温高塑性(大)应变胶粘剂。以Ⅳ号胶为代表着重研究了这些溶液型共聚-共混聚酰胺酸在热酰亚胺化为最终产物过程中,各个阶段的特征及对性能的影响。结果发现,急剧酰亚胺化(155℃附近)之后,聚合物的T(>280℃)便已接近最大值,认为继续的酰亚胺化反应至完全(225℃附近)是在软玻璃态中进行的。文中确定了该胶粘剂呈现优良应变特性和粘结性的热-酰亚胺化温度是250—260℃。     

百部叶碱核心骨架新合成策略探索:含三个连续手性中心双环中间体的对映选择性构筑

本文研究了百部叶碱核心骨架新合成策略中一个含三个连续手性中心双环中间体的对映选择性构筑.以本实验室发展的(S)-苹果酰亚胺为手性源,后者经三步反应转化为氮上带亲核性烯丙基硅烷取代基的苹果酰亚胺.正丁基格氏试剂对上述苹果酰亚胺的加成区域选择性地引入百部叶碱的C-3侧链.关键的环化反应为三氟化硼合乙醚引发的分子内氮杂Sakurai反应.该反应能高产率地进行,但生成4个非对映立体异构体.通过细致的二维核Overhauser效应(NOESY)研究确定了上述4个非对映立体异构体中两新形成手性中心的立体化学,并确定了主要立体异构体(产率:35%)为合成百部叶碱天然对映体所需. Wacker氧化生成标题化合物及少量区域异构体(醛),比例为18:1,合并产率50%.     

反相非水乳液法制备聚酰亚胺微球

在N,N-二甲基甲酰胺(DMF)/Pluronic-F127、十二烷基苯磺酸钠(SDBS)/液体石蜡(LP)反相非水乳液体系中,以均苯四甲酸二酐(PMDA)和4,4′-二氨基二苯醚(ODA)为单体合成聚酰胺酸(PAA),采用吡啶/乙酸酐脱水剂,对PAA化学酰亚胺化,并进一步热酰亚胺化,制得PI耐热微球.产物通过红外、热重、扫描电镜表征.结果表明,较高的固含量和良好的乳液分散性有利于PI微球的形成;反相非水乳液体系稳定的配比条件是,VDMF∶VLP为1∶4,MF127∶MSDBS为3:2,乳化剂用量为9 wt%;在此配比条件下,当固含量为20%,热酰亚胺化温度不高于330℃时,可制得分散良好、球形规整、高热稳定性的PI微球,其粒径约为10μm.     

芳香甲（乙）酯）铵盐的酰胺化与酰亚胺化

用热分析方法得出,由芳香酸甲酯或乙酯与4,4’-二氨基二苯甲烷制备的铵盐的酰胺化,酰亚胺化反应,较芳香酸的铵盐更易进行,反应温度和表观活化能均比四酸铵盐时低。由铵盐生成的聚酰亚胺具有很好的热氧化稳定性。     

Structure and properties of polyimide films during a far‐infrared‐induced imidization process

The conversion of poly(amic acid) into polyimide (PI) was achieved with far‐infrared radiation (FIR) and conventional thermal treatments. The structure and properties of PI films during different stages of imidization were studied with Fourier transform infrared spectroscopy, weight‐loss analysis during imidization, tensile property measurements, and dynamic mechanical thermal analysis. The effects of the imidization degree, postimidization, and solvent on the thermal and mechanical properties of PI films were quantitatively investigated. The corresponding structural changes were also examined. The experimental results showed that the imidization process proceeded more quickly and more completely in an FIR oven than in a conventional oven. A prolonged FIR treatment at a lower temperature (25–100 °C) accelerated the imidization process. The tensile stress–strain curves had a fanlike distribution with the development of the FIR imidization process and a fishtail distribution with conventional thermal imidization. During FIR imidization, the best tensile properties were obtained at 340 °C, and thermooxidative degradation occurred at about 420 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2490–2501, 2004     

Effects of monomer structure and imidization degree on mechanical properties and viscoelastic behavior of thermoplastic polyimide films

Two thermoplastic polyimides based on a common diamine (3,4′-ODA) were synthesized using different dianhydrides, namely ODPA and BPDA by a two step method. Molecular weight was controlled by using PA as an end capping agent. Effects of imidization degree on the mechanical properties and viscoelastic behavior of thermoplastic polyimide films were investigated. Film samples with varying degrees of imidization were characterized using FTIR, DMTA and tensile properties testing. It was found that two polyimides have different rates of imidization because of difference in monomer reactivity and molecular structure. It was observed that with an increase in imidization degree there was a decrease in thermoplastic response and a change in viscoelastic behavior from liquid-like to solid-like. With increase in imidization degree the tensile modulus and tensile strength of the films were increased, whereas elongation at break and tensile breaking energy were found to decrease after a certain imidization temperature.     

Residual stress and optical properties of fully rod-like poly(p-phenylene pyromellitimide) in thin films: Effects of soft-bake and thermal imidization history

A soluble poly(amic acid) precursor solution of fully rod-like poly(p-phenylene pyromellitimide) (PMDA-PDA) was spin cast on silicon substrates, followed by soft bake at 80–185°C and subsequent thermal imidization at various conditions over 185–400°C in nitrogen atmosphere to be converted to the polyimide in films. Residual stress generated at the interface was measured in situ during imidization. In addition, the imidized films were characterized in the aspect of polymer chain orientation and ordering by prism coupling and X-ray diffraction. The soft-baked precursor film revealed a residual stress of 16–28 MPa at room temperature, depending on the soft bake condition: higher temperature and longer time in the soft bake gave higher residual stress. The stress variation in the soft-baked precursor film was not significantly reflected in the final stress in the resultant polyimide film. However, the residual stress in the polyimide film varied sensitively with variations in imidization process parameters, such as imidization temperature, imidization steps, heating rate, and film thickness. The polyimide film exhibited a wide range of residual stress, −7 MPa to 8 MPa at room temperature, depending on the imidization condition. Both rapid imidization and low-temperature imidization generated high stress in the tension mode in the polyimide film, whereas slow imidization as well as high temperature imidization gave high stress in the compression mode. Thus, a moderate imidization condition, a single- or two-step imidization at 300°C for 2 h with a heating rate of < 10 K/min was proposed to give a relatively low stress in the polyimide film of < 10 μm thickness. However, once a precursor film was thermally imidized at a chosen process condition, the residual stress–temperature profile was insensitive to variations in the cooling process. All the films imidized were optically anisotropic, regardless of the imidization history, indicating that rod-like PMDA-PDA polyimide chains were preferentially aligned in the film plane. However, its degree of in-plane chain orientation varied on the imidization history. It is directly correlated to the residual stress in the film, which is an in-plane characteristic. For films with residual stress in the tension mode, higher stress films exhibited lower out-of-plane birefringence, that is, lower in-plane chain orienta-tion. In contrast, in the compression mode, higher stress films showed higher in-plane chain orientation. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1261–1273, 1998     

Thermal imidization and structural evolution of thin films of poly(4,4'-oxydiphenylene p-pyromellitamic diethyl ester)

The evolution of chemical composition and structure during the thermal imidization of an ester-type polyimide precursor, poly(4,4'-oxydiphenylene p-pyromellitamic diethyl ester), in micrometer scale films were studied for a heating rate of 2.0 degrees C/min with time-resolved synchrotron X-ray diffraction, in-situ infrared spectroscopy, and modulated differential scanning calorimetry. Our analyses show that the precursor polymer undergoes imidization in a two-step process. In the first step, the precursor polymer is decomplexed from the residual solvent molecules, and in the second step, it undergoes imide ring formation with the release of ethanol as a byproduct. The imidization reaction starts around 210 degrees C and continues up to 320 degrees C. The thermal imidization reaction induces the structural evolution of the film. As the imidization reaction proceeds, the coherent length along the polymer chain axis increases. This imidization-induced structural evolution was found to occur via three steps: (i) initiation, (ii) the first crystallization, and (iii) the second crystallization. The initiation step is necessary prior to the evolution of the crystalline structure to increase the chain mobility of the precursor polymer chains, and it requires thermal heating up to at least 238 degrees C at which point 22.5% of the imidization is complete. Thereafter, the first crystallization occurs up to 310 degrees C, at which point 98.3% of the imidization is complete. In the range 310-380 degrees C, the second crystallization occurs and produces almost complete imidization of the polymer chains.     

Copolyimide imidization induced by far‐infrared radiation

The copolyimides derived from 3,4′‐oxidianiline (ODA), 4,4′‐oxydiphthalic anhydride (ODPA) and 3,3′,4,4′‐biphenyl dianhydride (BPDA) were synthesized in N,N‐dimethyl acetamide (DMAc) by a two‐step method. To control molecular weight, phthalic anhydride (PA) was used as an end‐capping reagent. The effect of far‐infrared radiation (FIR) on imidization of copolyimides was investigated by Fourier transform infrared spectroscopy (FT‐IR) and Thermogravimetric analysis (TGA), and was compared to conventional electrothermal imidization. The effect of imidization time and film thickness on weight loss of imidization process was also studied. The results show that the FIR can accelerate the imidization process of copolyimides compared with the conventional electrothermal treatment especially during the primary curing period. Weight loss of thin film is faster than that of thick film. In addition, molecular weight will influence the imidization process. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2154–2160, 2005     

聚醚型氨酯酰亚胺/二氧化硅杂化材料的合成与性能研究

利用Sol Gel共聚合反应制备出聚醚型氨酯酰亚胺 (PUI) /二氧化硅 (SiO2 )杂化材料 .利用NMR、FTIR、TG、DSC及SEM等测试手段对性能进行了基本表征 .FTIR研究结果发现在 10 0℃下能同时完成有机相PUI的亚胺化和无机相SiO2 凝胶网络的Sol Gel转变 .TG及SEM发现SiO2 含量为 9wt%时SiO2 聚集相粒径在 0 2～1 0 μm之间 ,耐热性明显提高并达到最佳 ;发现SiO2 含量的增加其颗粒粒径不断增大 ,并不断聚集成大粒径SiO2 相 ,有机和无机相分离明显 .DSC研究显示 ,SiO2 相的引入 ,对杂化材料聚醚软段富集相的Tg 不产生明显影响 .