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91.
在讨论(v,k,1)光正交码存在性的几个条件的基础上,利用组合学的知识及方法解决(v,k,1)光正交码的存在性,并给出一些结果。 相似文献
92.
本文合成了一系列聚砜—聚酯类嵌段共聚物。研究了这些共聚物的结构与性能的关系。发现这些共聚物的溶液性质,热性能及力学性能与共聚体中二元醇的结构有关。共聚物系由非晶相聚砜为连续相与晶相聚酯为分散相组成的两相体系。 相似文献
93.
研究了解析函数空间HL_ρ~P的Hadamard乘积,得到了HL_ρ~P的特征。特别,本文也得到了Bloch函数的一个特征。 相似文献
94.
95.
Costa AC Composto RJ Vlcek P Geoghegan M 《The European physical journal. E, Soft matter》2005,18(2):159-166
Using neutron reflectometry, the adsorption of diblock copolymers from a neutral polystyrene (PS) matrix is studied as a function
of substrate type and non-adsorbing block degree of polymerization. The block copolymer is poly(deutero styrene)-block-poly(methyl methacrylate) and the substrates are silicon oxide, SiOx, and SiOx functionalized with (3-aminopropyl)triethoxysilane (APTES). We have determined the equilibrium volume fraction-depth profiles
for such films, and compared them with volume fraction profiles generated by self-consistent mean-field (SCMF) theory and
find good agreement between the experimental and theoretical data. SCMF calculations show that the segmental interaction energy
between PS matrix chains and APTES is two orders of magnitude stronger than that between PS and SiOx. 相似文献
96.
分析我国现行生态保护建设政策,指出以往政策使用效果上的不足和补偿机制的对生态产品生产的激励作用,阐述了生态建设中资源转移对效率的关系,通过模型论证生态产品生产中为提高生产效率和社会福利对资源进行转移的必要性,探讨建立生态补偿机制的实现途径,并提出相应的政策建议。 相似文献
97.
Juan Rodriguez-Hernandez Emmanuel Ibarboure Eric Papon 《European Polymer Journal》2011,47(11):2063-2068
We describe the surface segregation of polypeptide-based block copolymer micelles to produce stimuli-responsive nanostructures at the polymer blend/air interface. Such structures were obtained by simultaneous surface migration and self assembly at the surface of diblock copolymer/homopolymer blends. We employed blends composed of homopolymer (PS) and an amphiphilic block copolymer polystyrene-b-poly(l-glutamic acid) (PS-b-PGA). The surface was functionalized based on the preferential segregation to the polymer blend/air interface of the hydrophilic PGA block of the diblock copolymer upon annealing to water vapor. The surface migration of the diblock copolymer to the interface was demonstrated both by XPS and contact angle measurements. As a consequence, the PGA interfacial attraction leads to a large surface excess on diblock copolymer which in turn, through macrophase and microphase separation, produced separated domains at the surface with regions composed either of homo or block copolymer. Herein we demonstrate that the use of asymmetric diblock copolymers with a higher content in PS lead to spherical micellar assemblies randomly distributed at the surface. As observed by AFM imaging the blend composition, i.e. the amount of block copolymer within the blend influences the density of micelles at the surface. Finally, when exposed to water, the pH affects the surface morphology. The PGA segments are collapsed at low pH values and extended at pH values above 4.8, thus inducing variations on the topography of the films at the nanometer scale. 相似文献
98.
Novel polyesteramide-based di- and triblock copolymers: From thermo-mechanical properties to hydrolytic degradation 总被引:1,自引:0,他引:1
Gaëlle Deshayes Cécile Delcourt Ingrid Verbruggen Lise Trouillet-Fonti Franck Touraud Etienne Fleury Philippe Degée Mathias Destarac Rudolph Willem Philippe Dubois 《European Polymer Journal》2011,(1):98-110
Two types of biodegradable poly(ε-caprolactone (CLo))-co-poly(ε-caprolactam (CLa)) copolymers were prepared by catalyzed hydrolytic ring-opening polymerization. For the first type of materials, the respective cyclic comonomers were added simultaneously in the reaction medium leading to the formation of copolymers having a random distribution of co-units within the polyesteramide sequence, as evidenced by 1H and 13C NMR. For the second type of copolymers, the cyclic comonomers were added sequentially in the reaction medium yielding diblock polyesteramides, again evidenced by NMR. The thermal and thermo-mechanical properties of the copolymers were investigated by DSC and DMA and correlated with the copolymer topology and composition. The copolymers were characterized by a storage modulus and α transition temperature intermediate to the modulus and Tg of the corresponding homopolymers. The chemical composition and molecular weight of the copolymers proved to have only a limited effect on the thermo-mechanical properties of the materials. The hydrolytic degradation of random copolymers was studied in a phosphate buffer at 60 °C and discussed in terms of chemical composition and molecular weight of the copolymers. 相似文献
99.
Houjian Gong Guiying Xu Hui Ding Xiaofeng Shi Yebang Tan 《European Polymer Journal》2009,45(9):2540-2548
The block polyethers with various branch structure, such as TEPA[(PO)36(EO)100]7, TEPA[(PO)36(EO)100(PO)36]7, and TEPA[(PO)36(EO)100(PO)56]7 were synthesized. Moreover, the aggregation behavior was investigated via the measurements of equilibrium surface tension, dynamic surface tension, and surface dilational viscoelasticity, in order to probe the effect of the block structure on the property of the branched block polyethers. The surface tension results show that the efficiency and effectiveness of the block polyethers to lower surface tension increase with the increase of the PO group numbers. The maximum surface excess concentration (Γmax) values and the minimum occupied area per molecule at the air/water interface (Amin) values of the branched block polyethers obtained from Gibbs adsorption equations increase and decrease with the increases of the PO group numbers, respectively. The dynamic parameters n and t* representing the diffusion speed of the polyether molecules from bulky solution to the subsurface and from the subsurface to the air/water surface are obtained according to the equation proposed by Rosen. The results show that the n values firstly increase and then decrease and t* values decrease with the increase of the polyether concentrations. The results of surface dilational viscoelasticity show that the dilational modulus of TEPA[(PO)36(EO)100(PO)56]7 is the largest among the three block copolymers at the low concentration (<1 mg L−1) but that of TEPA[(PO)36(EO)100]7 is the largest at the high concentration (>1 mg L−1). 相似文献
100.
嵌段共聚物在乳液聚合和分散聚合中的应用 总被引:4,自引:0,他引:4
综述了嵌段共聚物在乳液聚合和分散聚合中作为稳定剂应用的进展,主要讨论了共聚物化学组成,比例,分子量,浓度以及胶束形成等因素对聚合体系的影响。 相似文献