茂基稀土胺化物的合成及其作为单组份引发剂引发极 性单体聚合的研究

综述了近年来我们在茂基稀土胺化物的合成、结构及其催化极性单体,包括甲基丙烯酸甲酯、甲基丙烯酸N,N-二甲氮乙酯、异氰酸苯酯的聚合和ε-己内酯开环聚合的研究结果。讨论了茂基稀土胺化物的结构与催化活性的关系,提出了可能的聚合反应机理。     

二氮双环阳离子游离基中N,N'-三电子键

用从头算HF/3-21+G^*优化了二氮双环[m,n,l]游离基阳离子(m,n,l≥2～5)。分子[4,4,4]和[2,2,2]^+.,[3,3,3]^+.,[4,4,4]^+.游离基阳离子的优势构型有D3对称性,而其它游离基阳离子的优势构型为非对称性。通过比较这些阳离子几何构型,HOMO和NHOMO(即NextHOMO和HOMO-1),和由MNDO计算确定的原子对作用能,表明当二氮双环游离基阳离子的桥链(CH2)n的n≥3时,桥头氮原子通过空间相互用用形成了一个弱的N,N'-三电子σ键。形成的三电子键强度不随环的扩大而增强。而三电子键强度被两个因素影响：一个是桥头氮原子间的p轨道重叠的取向;另一个是它们相应p轨道成分。     

Synthesis and Characterization of Multi-layered Core/Shell Particles by Sequential Emulsion Polymerization

A series of core/shell particles were prepared by sequential emulsion polymerization. The core/shell particles consisting of poly(methyl methacrylate) core grafted with using rubbery layer [poly(butyl acrylate)co-(styrene)] and then glassy layer [poly(methyl methacrylate)-co-(ethyl acrylate)] were prepared. The conditions which led to controlled particle size and morphology were discussed. A highly cross-linked structure was formed in both the cores and the shells by using a cross-linking agent, which could prevent the migration of hydrophobic shells to the inside of the particles. The core/shell particles were characterized by Fourier-transform infrared spectroscopy, solid state ¹³C-NMR. Thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC) were used to determine the thermal stability and glass transition temperature of the core/shell particles, respectively. Results of the particle size analysis indicate that particle sizes were decreased when there is a rubbery layer as outer layer (0.44 μm) whereas it increases when there is a glassy layer as outer layer (324 μm). Scanning electron microscopy (SEM) also confirms the multi-layers formation in the polymer.     

Synthesis of poly(butylene succinate) nanocomposites via in-situ interlayer polymerization: thermo-mechanical properties and morphology of the hybrid fibers

A series of poly(butylene succinate) (PBS) nanocomposites with the organoclay C₁₂PPh-Mica were synthesized by using the in-situ interlayer polycondensation of 1,4-butanediol with succinic acid. The PBS nanocomposites were melt-spun to produce monofilaments with various organoclay contents and draw ratios (DRs). The thermo-mechanical properties and morphologies of the PBS nanocomposites were determined using differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray diffraction, transmission electron microscopy, and a universal tensile machine. Some of the clay particles were found to be well dispersed in the PBS matrix, with some agglomerated at a size level greater than approximately 20 nm. The thermal degradation properties of undrawn PBS hybrid fibers were found to improve with increasing clay content. The ultimate tensile strengths and initial moduli of the hybrid fibers increased with increasing clay content at DR = 1. However, the ultimate strengths were found to decrease markedly with increases in DR from 1 to 6. In contrast to the trend for the tensile strengths, the initial moduli of the hybrid fibers increased only slightly with increases in DR up to 6.     

POLYMERIZATION OF N,N′-(PYROMELLITOYL)-BIS-L-LEUCINE DIACID CHLORIDE WITH HYDANTOIN DERIVATIVES BY MICROWAVE IRRADIATION

Facile and rapid polycondensation reactions of N,N′-(pyromellitoyl)-bis-L-leucine diacid chloride 1 with eight different derivatives of hydantoin compounds 2a-h were developed by using a domestic microwave oven in the presence ora small amount of polar organic medium such as o-cresol. The polycondensation reactions proceeded rapidly, compared with the conventional solution polycondensation, and was completed within 7-10 min, producing a series of novel optically active poly(amide-imide)s 3a-h with high yield and inherent viscosity of 0.35-0.65 dL/g. All of the above polymers were fully characterized by FT-IR, elemental analyses, inherent viscosity (ηiaa), solubility test and specific rotation. Some structural characterization and physical properties of these optically active poly(amide-imide)s are reported.     

Hydroxyl radical-mediated advanced oxidation processes for textile dyes: a comparison of the radiolytic and sonolytic degradation of the monoazo dye Acid Orange 7

Acid Orange 7, a textile azo dye, has been partially mineralized and degraded using -radiolysis and sonolysis. These two different advanced oxidation processes (AOP) are effective in producing OH radicals and cause complete destruction of the chromophore. The reaction mechanism of dye degradation has been probed by analyzing the reaction products with HPLC. In both cases, the final end products of degradation are oxalate and formate ions. The intermediates observed are all similar. While hydroxybenzenesulfonic acid is the major observed reaction intermediate in the oxidation processes, the pulse radiolysis studies indicate that the OH radical initiated pathway for attack occurs via the initial formation of 1,2-naphthaquinone and subsequent breakdown into oxalic acid.     

二甲基二烯丙基氯化铵反相乳液聚合动力学及机理的研究

研究以异构烷烃混合物为连续相,以丁二酸二(2-乙基)己酯磺酸钠(Sodium-di-2-ethylhexylsulfosuccinate,CH~3CH~2CH~2CH~2CH(C~2H~5)CH~2OCOCH(SO~3Na)CH~2COOCH~2CH(C~2H~5)-CH~2CH~2CH~2CH~3,AOT)和山梨糖醇单油酸酯(SMO)为乳化剂,以偶氮二异庚腈(ADVN)为引发剂的二甲基二烯丙基氯化铵的反相乳液聚合,得到了R~P~,~0=kc^0^.^4~Ⅰ~,~0c^0^.^5~A~O~Tc^-^0^.^4~S~M~Oc^3^.^0~M~,~0的表观动力学表达式。首次提出并研究了反相乳液聚合中单体在单体液滴和胶束中的分配系数对聚合动力学的影响,成功地解释了初始聚合反应速度和单体浓度三次方成正比的原因。通过对胶粒(latex)直径、单体在油相中的溶解度、聚合反应速度与AOT浓度及搅拌速度间的关系的测定,证明聚合反应是通过胶束(micelle)成核机理而进行的。通过对不同单体浓度下的^1H NMR盐效应的研究,证明溶液聚合的速度和单体浓度二次方成正比不是由于生成双分子π配合物,而是由静电屏蔽效应和粘度的改变引起的。     

二乙炔及其衍生物的聚合和光学性能的量子化学研究

主要报道利用半经验分子轨道方法PM3研究的五个二乙炔衍生物的结构, 并预计了其分子晶体的光学和聚合性能。这些化合物的几何构型参数以及由此形成的晶体的堆积参量均用能量梯度方法优化。同时, 从实验上研究了其中三个化合物的晶体在热和光环境下的聚合状况。理论预计和实验结果基本吻合。计算表明, 可聚合晶体应具有适当的堆积距d(～0.55nm)和倾斜角θ(～50°)。     

五元体系Li^+, Na^+, K^+, Mg^2^+/SO~4^2^- - H~2O 25℃相关 系的研究

用等温溶解平衡法研究了五元体系Li^+,Na^+,K^+,Mg^2^+/SO~4^2^--H~2O25℃溶解度,测得了平衡溶液的密度,获得了该五元体系25℃溶解度相图的十个无变量点和十种平衡固相。十个单盐结晶区分别对应于原始组分K~2SO~4,Li~SO~4.H~2O,MgSO~4.7H~2O,水合物Na~2SO~4.10H~2O,复盐3K~2SO~4.Na~2SO~4,Na~2SO~4.MgSO~4.4H~2O,Li~2SO~4.3Na~2SO~4.12H~2O,2Li~2SO~4.Na~2SO~4.K~2SO~4,Li~2SO~4.K~2SO~4和K~2SO~4.MgSO~4.6H~2O,此外没有产生新的复盐或固溶体。用现代电解质溶液理论---Pitzer模型校验该体系的溶解度测定值,结果令人满意。     

内消旋和外消旋2,3-二氰基-2,3-二苯基丁二酸二乙酯对苯乙烯聚合反应的影响

测定了题目化合物立体异构体在80℃和90℃引发苯乙烯的自由基聚合反应。在相同条件下, 较活泼的meso-体为引发剂时, 聚合速率大, 产物分子量小; 而较稳定的dl-体则聚合速率小, 产物分子量大。且在所有反应条件下分子量均随反应时间增长。研究结果认为它们不同的聚合性能主要与异构体热分解速率对聚合动力学的影响有关。