波聚合制备聚(天然橡胶-接枝-丙烯酰胺)吸水膨胀橡胶

采用波聚合工艺快速制备了聚(天然橡胶-接枝-丙烯酰胺)吸水膨胀橡胶.该波聚合过程能够在45℃左右被引发,最高波温达到112℃,波速0.3~1.0 cm·min-1.与传统间歇聚合工艺相比,波聚合制备样品的接枝效率达到51.8%,是传统间歇聚合制品的2.8倍;最大吸水倍率为7.66 g·g-1,是传统聚合制品的1.6倍;聚合时间为传统间歇聚合的1/8.扫描电镜观测发现,波聚合制备的吸水膨胀橡胶呈现均匀分布的蜂窝状微孔结构,孔直径在4~10μm之间,该结构有利于橡胶在保持高强度和弹性的同时,提高吸水性能;而传统间歇聚合制品内则以小于2μm的微孔为主,同时有少数近毫米级的条形大孔存在.     

波聚合体系、引发、过程及应用

波聚合是一种通过局部反应区域向未反应区域连续移动将单体转化为聚合物的反应模式,具有简便快速、节能降耗和产物性能优异等优势,是化学合成、功能材料与结构材料制备的新方法。本文对波聚合反应体系、引发、过程、应用及存在问题等方面进行综述。重点评述了新型波聚合体系如二元或多元体系、离子液体体系、深共晶溶剂体系等;新型引发剂如光引发剂和离子液体引发剂等特殊引发剂;波聚合反应体系中的助剂如填料、交联剂、链转移剂、活化剂、增稠剂、表面活性剂和催化剂等对聚合过程和产物结构性能的影响;新发展的引发方式如紫外线、水、等离子体和耦合引发等;以及特殊波聚合过程。最后,展望了波聚合存在问题和商业化应用的研究方向。     

A Zn(Ⅱ) Coordination Polymer Based on a Flexible Polycarboxylate Ligand 5-(4-Hydroxypyridinium-1-ylmethyl)-isophthalic Acid: Synthesis,Structure, and Property

A Zn(Ⅱ) supramolecular coordination polymer, {[Zn_2(L)_2(m-bix)(H_2O)]·6 H_2O}n(1), with an interesting 1 D→2 D polythreading array from a flexible and angular organic aromatic polycarboxylate ligand 5-(4-hydroxypyridinium-1-ylmethyl)isophthalic acid(H2 L), and N-donor ligand 1,3-bis(imidazol-1-ylmethyl)benzene(m-bix), has been obtained under hydrothermal conditions and characterized by elemental analysis, powder X-ray diffraction(PXRD), IR, thermal gravimetric analyses(TGA) and single-crystal X-ray diffraction. In 1, the Zn(Ⅱ) center has two coordination geometries. One exhibits a trigonal bipyramidal coordination sphere, and the other is a tetrahedral geometry; L2-has two different coordination modes, with one connecting three Zn(Ⅱ) ions through two monodentate carboxylate groups and the monodentate hydroxyl group, and the other bridging two Zn(Ⅱ) ions through two carboxylate groups. The L2-anions connect the Zn(Ⅱ) centers forming an infinite 1 D tubular structure. These 1 D tubes are interconnected by the m-bix spacers to form a 2 D framework. Such 2 D layers are further assembled into a 3 D supramolecular network via hydrogen bonds. Meanwhile, the luminescent property of 1 has also been investigated in detail.     

Amberlite XAD-2000树脂固相萃取富集-火焰原子吸收法测定水中痕量铅

用Amberlite XAD-2000树脂键合8-羟基喹啉固相萃取富集水中痕量铅,然后用火焰原子吸收法测定。实验了pH,样品处理速度,洗脱剂的类型、用量、浓度、处理速度等因素对铅回收率的影响。在最优条件下,树脂对铅的最大吸附量7.2 mg Pb/g树脂,回收率92%;且该方法抗干扰能力强,可用于环境水样检测和干扰离子存在下（如海水中）痕量铅的检测。