Free-Standing Nanomaterials from Block Copolymer Self-Assemblyllye88 化学所Main ReferenceOutlineIntroduction Experimental Part Results and Discussion Conclusions Innovations and Problems References1. IntroductionAmphiphilic block copolymers (BCs) could control material interfaces . The 3D construction is directed by the assembly of BCs micelles prepared in situ during the spin-coating of the block copolymer solution. BCs in selective solvent lead to the preparation of core -shell micelles with a dense insoluble core and a diffuse shell partially swollen by the solventa dense insoluble core内核micellesa diffuse corona核冠In this work，the preparation of stable nanostructure assemblies in one step from homogeneous solutions of ABA triblock copolymers. The success of this strategy is essentially due to the design of very stable micelles prepared and self- assembled in situ in few seconds by solvent evaporationSelf-Assembly NanomaterialsThe glassy PSAN blocks will enable the formation of compact aggregates constraining the micelles to be kinetically frozen at room temperature whereas the flexible PEO block will enable the dynamic transitions between looped and bridged chain conformations.looped bridged Photon Cross Correlation SpectroscopyPhoton Cross Correlation Spectroscopy（PCCS），光子交叉相 关光谱法 PCCS已用于纳米颗粒粒径测量,其技术日益成熟并成为纳米 颗粒粒径测量的有效方法。其测量原理是建立在颗粒的布朗 运动之上。随着颗粒的布朗运动,散射光强围绕某一平均值 不断起伏涨落。 PCCS可以直接测试高浓度试样而不需要稀释。测量结果完全 真实的反映了被测试样品的实际粒度及分布状态 PCCS测定的参数为：平均粒径和多分散指数吴立敏，王晓艳. 纳米、亚微米颗粒粒度的测量光子相关光谱法,上海计量测试 ， 2003年 30卷 3期2.Experimental PartpSythesis of the Triblock Copolymer a. Esterification PEO+Acryloyol Chloride（丙烯酰氯） PEO-acrylate(I) b. Intermolecular Radical Addition I+MAMA-SGI alkoxyamine macroalkoxyamine-based PEO(II) c. Preparation of Triblock CopolymerII+Styrene+Arylonitrile P(St317-co-AN262)-b-PEO795-b-P(St-co-AN) pPreparation of Polymer Films a. Dissolving the Triblock Copolymer in a DMF/toluene mixture b. Spin-coating the homogeneous solution onto a Si wafer evaporate solventSynthetic Producure3.Results and DiscussionpSythesis of the Triblock Copolymer Precursor pPreparation of Particle Nanomaterial pPreparation of “Spider Web” Nanomterial3.1 Preparation of Particle Nanomaterial The preparation of superstructure homogeneous solution : PSAN-b-PEO-b-PSAN selective solution： DMF/toluene (50/50 v/v) , 100 mg/mLspin-coated on Si wafer No micelle could be detected in the solution by PCCS, even after increasing the concentration up to 200 mg/mL, which seems to indicate a high CMC in this solvent system. Beyond this concentration, the polymer solution was too viscous to be analyzed.选择性溶剂 DMF，二甲基甲酰胺，极性非质子性溶剂 Toluene，甲苯，非极性溶剂Figure 2(A) . Self-standing nanoparticle superlattice film prepared from a DMF/toluene (50/50, v/v) copolymer solution. AFM top view of the superstructure and size distribution of particle diameter determined by a picture analysis over 100 particles.Diameter：c.a. 50nmNarrow size distribution AFM imagea Large-scaled AFM image of the nanoparticle film top surface. b,c 3D AFM images showing the high regularity in roughness with Z value(21.3nm) close to the Radius(c.a. 25nm) of one polymer particle.A dense packing of nanoparticlesLarge-scaled AFM imageFigure 2 (B) SEM top, bottom, and cross sectional view of a stretched nanoparticle film. stretching the film can take place without forming cracks. (C) Crack free stretched nanoparticle film. (D) Enlargement of the cross-section showing a homogeneous nanoparticle morphology.SEM image The water contact angle (WCA) of the nanoparticle film was measured to be 35, which confirms the presence of hydrophilic PEO on the particle film surface. The hydrophobic PSAN core is “shielded” by the PEO corona ，so the surface properties of the material is only related to the thin PEO layer.推断不溶性的PSAN嵌段：内核（micellar core）spherical micelle可溶的的PEO嵌段：核冠（micellar corona）A dense packing of nanoparticlesFilmFormation Mechanisim利用水触角测量仪进行电晕处理聚合物薄膜的试验方法Formation Mechanisim of Nanoparticle FilmFigure 3. the self-assembly of PSAN-b-PEOb-PSAN into nanoparticle filmABA Triblock Copolymer After the appearance of micelles, the solvent evaporation leads to a progressive decrease of the micelle-to-micelle distance. When micelles are close enough to interact, dynamic association could take place through bridged conformations of the ABA polymer chains，which leads to permanent nanomaterials. First solubilized the copolymer in DMF (100 mg/mL) followed by a slow addition of water. Dialyze remove DMF In this case, micelles were detected in PCCS in high concentration with a hydrodynamic diameter of 110 nm, which confirms the ability of the BC to be assembled into micellar morphology.DMF/water This alternative strategy seems to be less efficient in terms of particle organization. loose During the spincoating of the water-based dispersion, micelles c