階層結(jié)構(gòu)復(fù)合微球的制備、組裝與表面潤濕性研究.pdf

1、The development of polymer microspheres has great influence on our economy and life. It has become an increasingly important subject to achieve desirable physical properties for coatings, light-sensing materials, bio-med

2、icine, and so on.Furthermore, the morphology and size of particles are key factors to determine potential applications of polymer microspheres. So that, great interest has been focused on the morphology control of polyme

3、r microspheres, and the microspheres with different novel morphologies have been prepared. Amongst, the hierachical microspheres have attracted more and more attention because of their wide range of applications, e.g. su

4、rface enhanced Raman scattering (SERS), heterogeneous catalysts, and most importantly, fabrication of superhydrophobic materials. As we know, the raspberry hybrid particle possesses well-defined hierarchical structure,wh

5、ich consists of a microsized core decorated with nanoscaled particles on the surface. Thus, nowadays, raspberry hybrid particles have been intensively employed by more and more researchers to prepare superhydrophobic fil

6、ms with a dual-size hierarchical structured surface.
　　 This study aims at the preparation of raspberry, core-shell and triangle particles with controllable morphologies by different emulsion system (seed emulsion,

7、r>　　miniemulsion) based on the interface physical chemistry theory, and the assembly of these particles to fabricate particulate surface with particular wettability. The main content is as follows:
　　 1. raspberry-l

8、ike SiO2/PS particles were prepared by introducing of MPS-modified SiO2 particles into radiation miniemulsion polymerization of St. MPS modification with a lower cover density of 0.90 molecules/nm2 on the surface of SiO2

9、 is a crucial step to form a raspberry-like structure. The WSt/o-SiO2 (weight ratio of St to o-SiO2) and surfactant concentration also influence the morphology and wettability of the resultant SiO2/PS hybrid particles. T

10、he optimum WSt/o-SiO2 and SDS concentration for well-defined raspberry SiO2/PS particles is 50 and 6.94 mM, respectively. When the raspberry SiO2/PS partieles were deposited on a glass substrate from ethanol dispersion,

11、a film with dual-size roughness on the surface can be obtained. The surface of the film exhibites superhydrophobic property with a water contact angle of 151°and a large contact angle hysteresis(～116°). Compared with the

12、 traditional superhydrophobic surface, the as-prepared layer shows strong adhesion to water. The mechanism of the superhydrophobilicity and high adhesion to water produced on the raspberry SiO2/PS particulate film was co

13、nsidered to be the Gecko's state because of the van der Waals force between water and PS nanospheres on the film surface and the large density of the PS nanoparticles contacted with water(～1.55×107/mm2).This kind of supe

14、rhydrophobic particulate film can be used as a “mechanical hand” for transportation of small water droplets without lost, thus it may have potential applications in industrial field.
　　 2. Submicron-sized polystyrene

15、/polyacrylonitrile(PS/PAN) hybrid particles were
　　prepared by Υ-ray-induced seeded polymerization, in which the mono-disperse poly
　　(acrylic acid) (PAA)-functionalized PS particles were used as seed particles a

16、nd
　　acrylonitrile (AN) as the second monomer. The morphology of the PS/PAN hybrid
　　particles could be easily controlled by the pH value of seeded emulsion system. In
　　particular, with the increase of pH va

17、lue from 4 to 9.6, the morphology of the
　　corresponding PS/PAN hybrid particles gradually changed from core-shell to well-defined raspberry-like structure. The result of X-ray photoelectron spectroscopy
　　(XPS)

18、spectrum revealed the existence of PAN on the surface of the resultant hybrid particles. In addition, the particulate films were constructed by assembling these raspberry-like particles on glass substrates. Without any t

19、reatment, superhydrophilic surfaces can be obtained and the contact angle of water on the dual-sized structured surface is highly influenced by the micro/nano surface structure of raspberry-like particles.
　　 3. It i

20、s well know that silica must be modified with silane coupling agent, such as MPS, to improve the affinity of SiO2 particles to organic components before they can be used as carrier to load polymer. However, recently, we

21、have successfully prepared raspberry silica/polyacrylonitrile (SiO2/PAN) hybrid particles by Υ-ray radiation induced seeded polymerization using unmodified SiO2 particles (590 nm) as seeds.The surface morphologies of the

22、 obtained SiO2/PAN can be easily adjusted by the weight ratio of AN to SiO2 seeds. Most importantly, superhydrophilic surfaces can be obtained by assembling these raspberry-like SiO2/PAN particles on glass substrates, an

23、d the contact angle of water on the dual-sized structured surface is greatly influenced by the micro/nano surface structure of raspberry-like particles.
　　 4. PS/silica hybrid microspheres with core-shell and raspber

24、ry-like structure were prepared respectively with different sol-gel reaction catalysts (NH3·H2O,
　　diethanolamine, triethylolamine and triethylamine) in the presence of PS microspheres. The PS microspheres were prepa

25、red by dispersion polymerization using poly(vinylpyrrolidone) (PVP) as the stabilizer. Since the seed PS microspheres contain PVP molecules on the surface, which was facilitated to give perfect location of silica on PS m

26、icrospheres. After calcination of the core/shell structured particles at
　　800 ℃, hollow silica microspheres were successfully prepared. The formation of hollow silica particles strongly indicates that PVP-stabilized

27、 PS microspheres prepared by dispersion polymerization can be successfully employed to the fabrication of a well-defined silica layer due to the existence of PVP molecules on the surface. The wettability of the PS and PS

28、/SiO2 microspheres was also characterized by measuring the water contact angle of the corresponding particulate film. Furthermore,a novel strategy has been designed for the preparation of triangle polystyrene/SiO2 (PS/Si

29、O2) hybrid particles using radiation-induced seeded emulsion polymerization from above PS/SiO2 seed particles. The triangle particles can be fabricated in relatively high yield when the weight ratio of monomer/seed parti

30、cles (WSt/PS) is 5. Moreover, the size of the protruded PS bulbs of the triangle particles obviously increases with the weight ratio of monomer/seed particles from 1.25 to 5. This novel method is applicable to the prepar

31、ation of anisotropic hybrid particles from polymer/inorganic core-shell particles.
　　 5. Polystyrene (PS) microspheres with hydrophilic β-cyclodextrin (β-CD) shell were fabricated one-step via Υ-ray radiation induced

32、 emulsion polymerization in a simple ternary system of styrene/β-CD/water (St/β-CD/water) at room temperature.The solid inclusion complex of St and β-CD (St/β-CD IC) particles formed at the St droplets-water interface ac

33、t in-situ as the surfactant not only to stabilize the emulsionbut also make contribution to the formation of a hydrophilic β-CD shell on the prepared PS microspheres, which was observed by TEM and XPS investigation. The

34、average size of the PS particles is dependent on the weight ratio of β-CD to St(Wβ-CD/St), which increases from 186 nm to 294 nm as Wβ-CD/St rises from 5％ to12.5%. The water contact angle (CA) of the obtained PS latex fi

35、lm was measured to study the hydrophilic property of PS microspheres. The results show that all the CA of the obtained PS latex film are lower than 90°, and reduce with the content of β-CD even t0 36°. Thus, this work pr