末端化聚酰胺和交联剂及光酸产生剂所组成的三元负型光敏支化聚酰胺

研究了由未端化支化聚酰胺、交联剂(MBHP)和光酸产生剂(PTMA)所组成的三元负型光敏聚合物体系.其中,不对称ABB′型单体4-(2,4-二氨基苯氧基)苯甲酸3在亚磷酸三苯酯(TPP)和吡啶(Py)的存在下,通过缩合聚合得到支化聚酰胺a,由其1H-NMR数据计算得支化度(DB)为0.36.接着用肉桂酰氯对支化聚酰胺进行末端化.采用IR,1H-NMR,GPC,TG/DTA对支化聚酰胺和末端化支化聚酰胺b的结构和性能进行了表征.由85wt%末端化支化聚酰胺b、10wt%交联剂(MBHP)和5wt%光酸产生剂(PTMA)所组成的光敏聚合物体系,在100℃预烘10min,采用436nm(g-line)紫外光曝光,随后在25℃于二甲基甲酰胺中显影10s,用水漂洗,110℃后烘3min后,得到负型图案,边界清晰且分辨率达40μm.     

New Synthetic Reactions Based on the Onium Salts of Aza-Arenes [New synthetic methods (29)]

Effective syntheses employing 2-halogenated pyridinium, benzoxazolium, benzothiazolium, and pyridinium salts have been accomplished in the absence of strong acids and bases. Activation of carboxylic acids or alcohols with these onium salts leads to 2-acyloxy and 2-alkoxy intermediates which can be transformed into esters, amides, thiol esters, (macrocyclic) lactones, acid fluorides, olefins, allenes, carbodiimides isocyanates, isothiocyanates, nitriles, and isocyanates. The possibility of performing stereospecific syntheses (involving configurational inversion) with onium salts deserves attention.     

Morphological similarity of road networks and cracks

An investigation was made regarding to what extent road network patterns are reproduced by a crack model from a viewpoint that they seem to resemble crack patterns in morphology. A desiccation model using double-layered cellular meshes was considered with the parameters representing the anisotropy of the material and the coarseness of grains, together with the introduction of singularities in points and in lines. The model can generally reproduce the real crack patterns and the road network patterns of cities with characteristic morphology by appropriately choosing the values of parameters, indicating that the similar mechanism acts on the formation of road networks and cracks of material although the relevant scales of space time differ from each other. Factors which make the road networks more complex and irregular in morphology were also investigated.