6FAPE基含氟聚酰亚胺的结构与性能研究

利用含氟二胺单体4,4'-双(4-氨基-2-三氟甲基苯氧基)二苯醚(6FAPE),分别与1,2,3,4-环丁烷四酸二酐(CBDA)、3,3',4,4'-二苯醚四酸二酐(ODPA)、3,3',4,4'-联苯四酸二酐(BPDA)、3,3',4,4'-二苯甲酮四羧酸二酐(BTDA)和均苯四甲酸二酐(PMDA)进行低温缩聚反应,经热酰亚胺化制备出5种聚酰亚胺(PI)薄膜,考察了其光学透明性和热性能,研究了聚酰亚胺分子结构与性能的关系.结果表明,CBDA基含氟PI薄膜在可见光波长范围内(400～700nm)具有优异的光学透明性,450nm处的透光率为84.6%,且5种含氟PI薄膜在光通讯波段(1.30μm和1.55μm)均无明显吸收;除CBDA外,含氟PI薄膜均具有良好的热稳定性,5%热失重温度超过530℃;5种含氟PT薄膜的玻璃化转变温度Tg均在200℃以上,且CBDA基舍氟PI薄膜的Tg最高,达到265.5℃.     

无色透明耐高温聚酰亚胺薄膜的制备与性能研究

分别采用两种联苯型二酐单体,对称结构的3,3',4,4'-联苯四甲酸二酐(s-BPDA)以及不对称结构的2,3,3',4'-联苯四甲酸二酐(a-BPDA)与含氟芳香族二胺1,4-双(4'-氨基-2'-三氟甲基苯氧基)联苯(TFDAB)通过两步缩聚法制备了两种聚酰亚胺材料PI-1(s-BPDA/TFDAB)与PI-2(a-BPDA/TFDAB).研究结果表明,不对称结构可以显著增加PI薄膜在可见光区的透明性.25μm厚的PI-2薄膜在450nm处的透光率达到93%,而同样厚度的PI-1薄膜的透光率只有67%.此外,在PI分子结构中引入不对称结构不会牺牲材料的耐热稳定性、力学性能与介电性能.     

含螺环结构的二胺及其聚酰亚胺的合成与性能

首先,以双酚A和甲磺酸反应合成出3,3,3',3'-四甲基-6,6'-二羟基-1,1'-螺旋双茚满,然后与2-氯-5-硝基三氟甲苯反应得到3,3,3',3'-四甲基-6,6'-双[4-硝基-2-三氟甲基苯氧基]-1,1'-螺旋双茚满,最后在Pd/C-水合肼还原作用下得到3,3,3',3'-四甲基-6,6'-双[4-氨基-2-三氟甲基苯氧基]-1,1'-螺旋双茚满。采用上述二胺单体分别与1,2,3,4-环丁烷四酸二酐、均苯四甲酸二酐、联苯二酐、3,3',4,4'-二苯醚四酸二酐、3,3',4,4'-二苯酮四酸二酐和六氟二酐通过两步法制备出6种含螺环结构的聚酰亚胺(PI)。采用核磁、红外光谱、X射线衍射、紫外-可见光谱、热重分析、差示扫描量热分析和溶解性测试等手段表征了所得化合物和PI的结构与性能。研究结果表明,这些含螺环的PI主要表现为非晶结构和较大的分子链间距离,且具有良好的溶解性、光学性能和热性能。     

共聚物链结构对共聚型含氟聚酰亚胺薄膜性能的影响

以4,4'-二氨基-2,2'-双三氟甲基联苯(TFMB)、4,4'-(六氟异丙烯)二酞酸酐(6FDA)和3,3',4,4'-联苯四甲酸二酐(BPDA)为反应单体,改变非含氟BPDA单体在二酐中的配比和加料方式制备出一系列共聚型含氟聚酰亚胺(PI)薄膜并表征和分析其性能,研究了共聚物链结构对其性能的影响。结果表明,BPDA单体的加料方式及其在二酐单体中的比例均影响薄膜的性能。共聚型含氟PI薄膜在室温下均溶于非质子极性溶剂,且在可见光范围内有较高的透光率。随着非含氟二酐单体BPDA含量的提高薄膜的光学性能略有降低而其热性能和力学拉伸性能提高。非含氟二酐单体占二酐单体的比例为68.97%的共聚型PI薄膜,在500 nm处的透过率达到96.01%;非含氟二酐单体占二酐单体比例为35.71%的共聚型PI薄膜失重10%的热分解温度为595.23℃,拉伸强度为100.98 MPa。同时,BPDA加料方式的改变对共聚型PI薄膜的光学性能、热学性能和力学拉伸性能均有不同程度的影响。     

含氟半脂环透明聚酰亚胺薄膜的制备和性能

分别将脂环族二酐单体1,2,3,4-环丁烷四酸二酐(CBDA,Ⅰ)、1,2,4,5-环戊烷四酸二酐(CPDA,Ⅱ)和1,2,4,5-环己烷四酸二酐(CHDA,Ⅲ)与芳香族含氟二胺1,4-双(4-胺基-2-三氟甲基苯氯基)苯(6FAPB,a)和4,4′-双(4-胺基-2-三氟甲基苯氧基)联苯(6FBAB,b)反应制备两个系列的含氟半脂环族聚酰亚胺(PI),研究了PI薄膜的热性能和光学性能.结果表明,制备出的PI薄膜具有良好的热稳定性,在氮气中起始热分解温度超过450℃、玻璃化转变温度超过250℃,在可见光范围内(400-700 nm)具有优良的透明性,450 nm处的透过率超过88%.两类PI薄膜在光通讯波段(1.30μm与1.55μm)均没有显著的吸收.     

可溶性透明含氟聚酰亚胺薄膜的合成与性能

利用3种二胺单体1,4-双(4-氨基-2-三氟甲基苯氧基)苯、4,4’-双(4-氨基-2-三氟甲基苯氧基)二苯醚和4,4’-双(4-氨基-2-三氟甲基苯氧基)六氟丙烷分别与3种二酐单体1,2,3,4-环丁烷四酸二酐(CBDA)、均苯四甲酸二酐(PMDA)和3,3’,4,4’-二苯醚四酸二酐(ODPA)进行低温溶液缩聚反应,再经热酰亚胺化制备出9种聚酰亚胺(PI)薄膜。结果表明,这些PI具有较好的溶解性,可溶解于氨型强极性溶剂,在弱极性溶剂中也有一定的溶解性;CBDA和ODPA基PI在450 nm处的透光率超过80%,且CBDA基PI的紫外截止波长为310 nm,更接近无色,但其热稳定性最差,5%热分解温度在420℃左右,而PMDA和ODPA基PI的热稳定性较好。     

热和化学亚胺化对ODPA/ODA聚酰亚胺薄膜性能的影响

以4,4'-二胺基二苯醚(ODA)和3,3',4,4'-二苯醚四酸二酐(ODPA)为单体,采用两步法,分别经热亚胺化和化学亚胺化过程制备了两种聚酰亚胺(PI)薄膜,并对两种薄膜的性能进行了表征.傅立叶红外光谱(FT-IR)表明两种薄膜均已完全亚胺化.化学亚胺化的PI薄膜的玻璃化温度、热稳定性均高于热亚胺化的薄膜.拉伸性能测试表明热亚胺化的薄膜具有较高的断裂伸长率,而化学亚胺化的薄膜的拉伸强度、弹性模量较大.     

双胺芴基聚酰亚胺的合成及性能

以9,9-双(4-氨基苯基)芴(BAF)为二胺,分别与6种二酐单体——均苯四甲酸二酐(PMDA)、3,3’,4,4’-二苯醚四甲酸二酐(ODPA)、3,3’,4,4’-二苯甲酮四甲酸酐(BTDA)、3,3’,4,4’-联苯四甲酸二酐(BPDA)、4,4'-(六氟异丙烯)二酞酸酐(6FDA)和1,2,3,4-环丁烷四甲酸二酐(CBDA),经室温溶液缩聚反应得到聚酰胺酸溶液,再经化学酰亚胺化反应得到芴基聚酰亚胺(PI)。采用红外光谱、差示扫描量热分析、热重分析、溶解性测试及气体分离性能测试等手段对PI的结构和性能进行了表征。所合成的PI在N-甲基吡咯烷酮(NMP)等强极性溶剂中均具有良好的溶解性,且表现出良好的热性能,玻璃化转变温度(Tg)均在300℃以上,芳香族PI的起始热分解温度也均超过500℃,经600℃热处理的芴基PI,表现出了较好的气体渗透性能,但PI-CBDA膜的气体通量最小。     

高透明度可溶性聚酰亚胺共聚物的合成与表征

将含有柔性异亚丙基团的4,4'-(4,4'-异亚丙基二苯氧基)双苯酐(BSAA)与3,3',4,4'-二苯醚四酸二酐(ODPA)共同作为二酐单体与4,4'-二氨基二苯砜(DDS)共聚得到含砜基的聚酰亚胺,研究了共聚物在多种常用溶剂中的溶解性,并检测了共聚物薄膜的可见光透过性能和玻璃化转变温度,探讨了共聚物的溶解性、光透过性能以及玻璃化转变温度与柔性单体含量之间的关系.     

砜基取代高折射率高透明性聚酰亚胺的合成与性能

首先合成了同时含有砜基与硫醚键的二胺单体,4,4′-双(4-胺基苯硫基)二苯砜(BADPS).采用BADPS分别与4种二酐单体,3,3′,4,4′-联苯四羧酸二酐(BPDA)、3,3′,4,4′-二苯醚四羧酸二酐(ODPA)、4,4′-双(3,4-二羧基苯硫基)二苯硫醚二酐(3SDEA)以及1,2,3,4-环丁烷四羧酸二酐(CBDA)通过两步聚合工艺制备了一系列聚酰亚胺(PI).制备的PI薄膜具有优良的综合性能,包括良好的热稳定性、可见光波长范围内优良的透明性以及高折射率与低双折射.10mm厚的PI薄膜在450nm处的透光率超过80%.全芳香族PI(PI-1～PI-3)的折射率＞1.70,双折射＜0.02.     

检定和校准证书的异同与应用

本文介绍了检定和校准以及证书的两点相同、五点不同之处,说明了对检定证书和校准证书的正确应用。     

Heat and Mass Transfer and Modeling and Prediction of Environmental Catastrophes

Basic definitions and concepts of the physicomathematical theory of natural catastrophes are given. Possibilities of mathematical modeling of natural and technogenic catastrophes are discussed in the context of the theory of heat and mass transfer and the mechanics of reacting media. The importance of taking into account conjugate heat and mass exchange in modeling catastrophes is emphasized. A formula for evaluating the probability of a collisional catastrophe is given.     

Multi-ferroic and magnetoelectric materials and interfaces

The existence of multiple ferroic orders in the same material and the coupling between them have been known for decades. However, these phenomena have mostly remained the theoretical domain owing to the fact that in single-phase materials such couplings are rare and weak. This situation has changed dramatically recently for at least two reasons: first, advances in materials fabrication have made it possible to manufacture these materials in structures of lower dimensionality, such as thin films or wires, or in compound structures such as laminates and epitaxial-layered heterostructures. In these designed materials, new degrees of freedom are accessible in which the coupling between ferroic orders can be greatly enhanced. Second, the miniaturization trend in conventional electronics is approaching the limits beyond which the reduction of the electronic element is becoming more and more difficult. One way to continue the current trends in computer power and storage increase, without further size reduction, is to use multi-functional materials that would enable new device capabilities. Here, we review the field of multi-ferroic (MF) and magnetoelectric (ME) materials, putting the emphasis on electronic effects at ME interfaces and MF tunnel junctions.     

CellML and associated tools and techniques

We have, in the last few years, witnessed the development and availability of an ever increasing number of computer models that describe complex biological structures and processes. The multi-scale and multi-physics nature of these models makes their development particularly challenging, not only from a biological or biophysical viewpoint but also from a mathematical and computational perspective. In addition, the issue of sharing and reusing such models has proved to be particularly problematic, with the published models often lacking information that is required to accurately reproduce the published results. The International Union of Physiological Sciences Physiome Project was launched in 1997 with the aim of tackling the aforementioned issues by providing a framework for the modelling of the human body. As part of this initiative, the specifications of the CellML mark-up language were released in 2001. Now, more than 7 years later, the time has come to assess the situation, in particular with regard to the tools and techniques that are now available to the modelling community. Thus, after introducing CellML, we review and discuss existing editors, validators, online repository, code generators and simulation environments, as well as the CellML Application Program Interface. We also address possible future directions including the need for additional mark-up languages.     

Synthesis and luminescent properties of alkali-metal and ammonium fluorosulfatozirconates and fluorosulfatohafnates

We have synthesized a variety of alkali-metal and ammonium fluorosulfatometallates (titanates, zirconates, and hafnates). The alkali fluorosulfatozirconates and fluorosulfatohafnates have been shown to exhibit efficient roentgenoluminescence (RL) in the UV through visible spectral region, with a maximum at 390–440 nm. Their RL spectra depend significantly on their composition (cation, anion, and water content), coordination of KF and K₂SO₄, and relative amounts of fluorine and SO₄ groups. We have examined the effect of heat treatment on the RL of these compounds. The rubidium and cesium fluorosulfatozirconates Rb₃Zr₂F₉SO₄ · 2H₂O, Cs₂ZrF₂(SO₄)₂ · 2H₂O, Cs₈Zr₄F₂(SO₄)₁₁ · 16H₂O, and Cs₂ZrF₄SO₄ offer the most efficient RL.     

The shape and stability of wall-bound and wall-edge-bound drops and bubbles

The behavior of wall-bound drops and bubbles is fundamental to many natural and industrial processes. Key characteristics of such capillary systems include interface shape and stability for a variety of gravity levels and orientations. Significant solutions are in hand for axisymmetric pendent drops for a variety of uniform boundary conditions along the contact line with gravity acting normal to a planar wall. The special case of a wall-bound drop or bubble that is also pinned at an edge (i.e. a ‘wall-edge-bound’ drop) is considered here where numerical solutions are obtained for interface shape and stability as functions of drop volume, contact angle, fluid properties, and uniform gravity vector. For a semi-infinite zero-thickness planar wall (plate), a critical contact angle is identified below which wall-edge-bound drops are always stable. The critical contact angle is computed as a function of the gravity vector. The numerical procedure, which makes no account for contact angle hysteresis, predicts that such wall-edge-bound drops are unconditionally unstable for any gravity field with a component that is tangent to the wall while inwardly normal to the edge. Select experiments are conducted that support the conclusions drawn from the numerical results.