Article Cite This: Macromolecules XXXX, XXX, XXX−XXX
pubs.acs.org/Macromolecules
Precise Synthesis of Polymer Particles Spanning from Anisotropic Janus Particles to Heterogeneous Nanoporous Particles Wenzhong Zhai,†,‡ Yongyang Song,‡,§ Zhinong Gao,*,† Jun-Bing Fan,*,‡ and Shutao Wang*,‡,§
Macromolecules Downloaded from pubs.acs.org by UNIV AUTONOMA DE COAHUILA on 04/18/19. For personal use only.
†
Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 Hubei, P. R. China ‡ CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, CAS Center for Excellence in Nanoscience, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China § University of Chinese Academy of Sciences, Beijing 100049, P. R. China S Supporting Information *
ABSTRACT: Precise synthesis of polymer particles with topology and surface chemistry spanning from isotropy to anisotropy is critically needed for the fundamental research and industrial production. Herein, we report a seed wettability-manipulated emulsion interfacial polymerization to precisely synthesize polymer particles spanning from anisotropic Janus particles to spherical heterogeneous nanoporous particles. The variation of seed wettability from hydrophobicity to hydrophilicity allows a topological transition of obtained polymer particles from anisotropic Janus particles to spherical heterogeneous nanoporous particles, along with the distribution of surface chemistry. This large-span evolution of topology and surface chemistry of obtained particles is due to the shifting of the initially polymerizable emulsion interface from oil-in-water (O/W) to water-in-oil-in-water (W/O/W) driven by osmotic pressure. This seed wettability-manipulated emulsion interfacial polymerization is applicable to a variety of hydrophobic/hydrophilic monomer pairs, allowing flexible fabrication of diverse Janus particles and heterogeneous nanoporous particles.
■
uniform Janus particles from bread to pistachio shapes.29 Benefiting from topology and surface chemistry, these Janus particles have shown remarkable capacity in oil−water separation in comparison with their homogeneous particles.30 Different from the classical seed swelling polymerization, in our emulsion interfacial polymerization, we used noncross-linked polystyrene (PS) seeds to fabricate Janus particles.31 We demonstrated that noncross-linked PS seeds could not only tune the uniformity of obtained particles but also tune the interfacial growth toward the formation of Janus particles.31 However, the role of surface physicochemical features (e.g., wettability) of these seeds during the polymerization process of polymer particles remains unclear. Herein, we demonstrated that the role of seed wettability in the emulsion interfacial polymerization and merely manipulating seed wettability could precisely tune the topology and surface chemistry of polymer particles spanning from anisotropy to isotropy. By regulating seed wettability from hydrophobicity to hydrophilicity via a sulfonation reaction, the obtained polymer particles gradually shifted from anisotropic Janus particles to spherical heterogeneous nanoporous
INTRODUCTION Polymer particles, including isotropic spherical particles and anisotropic particles, are of particular utility and interest that have long been motivated by their commercial applications in chromatographic separation,1,2 drug delivery,3,4 tissue engineering,5 biological recognition and imaging,6 paints/coatings,7 solid surfactants,8−10 and self-assembly materials.11,12 These applications largely depend on topology and surface chemistry of polymer particles.13−18 Emulsion polymerization, as a traditionally leading synthetic strategy, has been industrially used to fabricate spherical polymer particles in large-scale.19−22 In recent years, based on the concept of phase separation, seed swelling polymerization is proposed to produce anisotropic particles by introducing cross-linked seeds into emulsion polymerization.23−25 During polymerization, seeds are first swollen with the hydrophobic monomer and then elastically collapsed to extrude an additional lobe.26 However, owing to the uniform collapse,27,28 seed swelling polymerization usually forms dumbbell- or snowman-shaped particles, which limits the flexibility to precisely tune the diverse topologies of obtained particles. Therefore, an efficient way is greatly desired to precisely synthesize polymer particles with topology and surface chemistry spanning from isotropy to anisotropy. More recently, we have developed an emulsion interfacial polymerization approach, achieving large-scale synthesis of © XXXX American Chemical Society
Received: January 29, 2019 Revised: March 19, 2019
A
DOI: 10.1021/acs.macromol.9b00199 Macromolecules XXXX, XXX, XXX−XXX
Article
Macromolecules
Figure 1. Seed wettability-manipulated emulsion interfacial polymerization. (a) Hydrophilic seeds with −SO3H groups can be fabricated by sulfonation reaction between hydrophobic seeds and sulfuric acid. (b) Schematic of hydrophobic seed-manipulated emulsion interfacial polymerization. (c,d) SEM images of the hydrophobic seed and correspondingly obtained anisotropic Janus particle. (e) HRTEM image of the anisotropic Janus particle cut by microtome and stained with phosphotungstic acid. (f) Schematic of hydrophilic seed-manipulated emulsion interfacial polymerization. (g,h) SEM images of the hydrophilic seed and the correspondingly obtained spherical heterogeneous nanoporous particle. (i) HRTEM image of the heterogeneous nanoporous particle cut by a microtome and stained with phosphotungstic acid. Synthesis of Anisotropic Janus Particles. Anisotropic Janus particles were synthesized by hydrophobic seed-manipulated emulsion interfacial polymerization. In brief, 0.2 g of hydrophobic seeds (with size of 1.22 ± 0.02 or 1.48 ± 0.03 μm) was first dispersed in 20.0 mL of aqueous sodium dodecyl sulfate (SDS) solution (0.25% w/v). Then, the hydrophobic seed solution was mixed with 10.0 mL of 1chlorodecane (1% v/v)-in-water emulsion containing 0.25% (w/v) SDS at 40 °C for 20 h. Subsequently, 1.5 mL of St, 1.0 mL of divinyl benzene (DVB), 0.5 mL of acrylic acid (AA), and 40.0 mg of 2,2′azoisobutyronitrile were dispersed in 10.0 mL of aqueous SDS solution (0.25% w/v), and then the mixture was emulsified to prepare hydrophobic monomer-in-aqueous hydrophilic monomer emulsion. The monomer emulsion was added into the aforementioned seed solution, and their mixture was subsequently stirred for 6 h at 40 °C. Finally, 5.0 mL of aqueous poly(vinyl alcohol) solution (1% w/v) was added to the aforementioned system. After deoxygenation bubbled with N2 for 15 min, the polymerization reaction was carried out for 14 h at 70 °C. For the hydrophobic seed (with the size of 0.44 ± 0.01 μm) manipulated emulsion interfacial polymerization, 0.1 g of hydrophobic seeds, 0.5 mL of St, 0.25 mL of DVB, and 0.5 mL of AA were added. For the hydrophobic seed with the size of 2.06 ± 0.03 μm manipulated emulsion interfacial polymerization, 0.1 g of hydrophobic seeds, 1.0 mL of St, 0.5 mL of DVB, and 0.5 mL of AA were added. The other reaction conditions were the same as the hydrophobic seed with the size of 1.22 ± 0.02 μm manipulated emulsion interfacial polymerization. Synthesis of Heterogeneous Nanoporous Particles. Spherical heterogeneous nanoporous particles were synthesized by hydrophilic seed-manipulated emulsion interfacial polymerization. Except for seeds, the other polymerization conditions were performed as same as the hydrophobic seed manipulated emulsion interfacial polymerization, including feed volume of hydrophobic and hydrophilic monomers, polymerization temperature, time, and initiator. Three-Phase Contact Angle of Seeds. The three-phase contact angle (CA) of seeds at oil−water interface was carried out by a gel trapping technique.34 First, a hot aqueous gellan solution (2.0 wt %) was added in a Petri dish at 50 °C. Then, prewarmed liquid paraffin was layered on the top of the gellan solution. A mixture of seed
particles. We demonstrated that the shifting of the initially polymerizable emulsion interface from oil-in-water (O/W) to water-in-oil-in-water (W/O/W) is responsible for the largespan variation of topology and surface chemistry of polymer particles. Meanwhile, a large variety of Janus particles and heterogeneous nanoporous particles can be precisely synthesized by changing different hydrophobic/hydrophilic monomer pairs and concentration of hydrophobic/hydrophilic monomers.
■
EXPERIMENTAL SECTION
Synthesis of Hydrophobic Seeds. Hydrophobic noncrosslinked PS seeds were synthesized by soap-free emulsion polymerization.32 In the synthesis of hydrophobic PS seeds with a size of 1.22 ± 0.02 μm, 6.5 mL of styrene (St), 0.1 g of sodium chloride, and 70.0 mg of ammonium persulfate (APS) were first dispersed in 60.0 mL of deionized water at room temperature. After deoxygenation bubbled with N2 for 30 min, the polymerization was performed at 70 °C for 24 h. The obtained hydrophobic seeds were washed with ethanol and deionized water for four times. Finally, these hydrophobic seeds were redispersed in deionized water and freeze-dried for 24 h. The other hydrophobic seeds with sizes of 0.44 ± 0.01, 1.48 ± 0.03, and 2.06 ± 0.03 μm were synthesized by feeding 1.0 mL of St and 70.0 mg of APS, 7.5 mL of St and 70.0 mg of APS, 6.0 mL of St and 40.0 mg of APS, respectively, while the other reaction conditions were the same as the synthesis of the hydrophobic seeds with the size of 1.22 ± 0.02 μm. Preparation of Hydrophilic Seeds. Hydrophilic sulfonated PS (SPS) seeds were prepared by sulfonation reaction between hydrophobic seeds and sulfuric acid under magnetic stirring.33 The sulfonation degree of SPS seeds could be regulated by controlling sulfonation time. In brief, 1.0 g of hydrophobic seed powder was well dispersed in 30 mL of sulfuric acid at 40 °C for a certain time. Subsequently, the obtained SPS seeds were washed with ethanol and deionized water four times. Finally, these SPS seeds were redispersed in deionized water and freeze-dried for 24 h. The sulfonation time of SPS-1 seeds, SPS-2 seeds, SPS-3 seeds, and SPS-4 seeds was 1, 2, 10 min, and 4 h, respectively. B
DOI: 10.1021/acs.macromol.9b00199 Macromolecules XXXX, XXX, XXX−XXX
Article
Macromolecules
Figure 2. Precise synthesis of polymer particles spanning from anisotropic Janus particles to spherical heterogeneous nanoporous particles by merely manipulating seed wettability in emulsion interfacial polymerization. Seed wettability can be regulated by controlling sulfonation time. (a−j) SEM images of seeds and their corresponding three-phase CA (θ). (a,f) PS-0 seeds. (b,g) SPS-1 seeds. (c,h) SPS-2 seeds. (d,i) SPS-3 seeds. (e,j) SPS-4 seeds. (k) Three-phase CA of seeds with different wettabilities. (l) Zeta potential of seeds with different wettabilities. (m) Sulfur atom content and sulfonation degree of seeds with different wettabilities. (n) Interfacial activity of seeds with different wettabilities. (o−s) SEM images, and (t−x) HRTEM images show polymer particles gradually change from the anisotropic Janus particle to the spherical heterogeneous nanoporous particle. (AutoPore IV 9500, USA) was used to measure the porosity of heterogeneous nanoporous particles.
solution (0.25 mL, 0.2 wt % seeds) and 2-propanol (0.25 mL) was slowly injected close to the liquid paraffin−water interface and kept for 6 h at 50 °C, allowing seeds to completely spread on the oil−water interface. After that, the mixture was cooled to room temperature to allow the gellan gel to solidify. Subsequently, a bubble-freed mixture of polydimethylsiloxane (PDMS) and the curing agent with a feed ratio of 10:1 was poured over the gellan gel surface after slowly removing liquid paraffin, and the system was cured for 48 h at room temperature. Finally, the solidified PDMS elastomer was peeled off the gellan gel surface and was washed in a water bath at 95 °C for 5 min to remove the residual gellan gel. Characterizations. Scanning electron microscopy (SEM, SU8010, Japan) was used to characterize the morphology of particles and those gel-trapped seeds. High-resolution transmission electron microscopy (HRTEM, FEI Tecnai G2 20, USA) was used to characterize the slice of polymer particles. An optical microscope (Nikon Ti-E, Japan) was used to observe the droplets and growth process of polymer particles. Zetasizer Nano ZS (Zen 3600, UK) was used to measure the zeta potential of seeds. X-ray photoelectron spectra (XPS, ESCALAB 250Xi, USA) were used to measure the content of −SO3H groups of SPS seeds. A mercury porosimetry
■
RESULTS AND DISCUSSION Seed Wettability-Manipulated Emulsion Interfacial Polymerization. Hydrophobic PS seeds were synthesized by soap-free emulsion polymerization, while hydrophilic SPS seeds were fabricated by sulfonation reaction between hydrophobic PS seeds and sulfuric acid (Figure 1a). As shown in Figure 1b, for a hydrophobic seed-manipulated emulsion interfacial polymerization, the polymerization allowed the formation of anisotropic poly(styrene-co-DVB) ⊃ poly(acrylic acid) (PSDVB ⊃ PAA) Janus particles (the symbol “⊃” represents the orientation of the hydrophobic concave surface and the hydrophilic convex surface of the Janus particles) (Figure 1c,d). The HRTEM image of the Janus particle revealed obvious two layers, through which the thickness of the hydrophilic PAA layer was 72.5 ± 10.2 nm (Figure 1e), while for a hydrophilic seed-manipulated emulsion interfacial polymerization (Figure 1f), the polymerization C
DOI: 10.1021/acs.macromol.9b00199 Macromolecules XXXX, XXX, XXX−XXX
Article
Macromolecules
(Figure 2o,t,p,u). When three-phase CA increased to 102.3 ± 2.3°, nanoporous particles with a small opening “mouth” were formed (Figure 2q,v). Further increasing the three-phase CA, the opening “mouth” of the obtained polymer particles closed and finally, spherical heterogeneous nanoporous particles were fabricated (Figure 2r,w,s,x). Correspondingly, the average pore sizes of these spherical heterogeneous nanoporous particles were approximately 42.6 and 16.5 nm, when hydrophilic SPS-3 and SPS-4 seeds were used in the polymerization system. Notably, the surface chemistry with respect to the amphiphilicity of the obtained particles also changed accompanying with their topology. Therefore, by merely manipulating seed wettability in emulsion interfacial polymerization, polymer particles spanning from anisotropic Janus particles to spherical heterogeneous nanoporous particles could be precisely synthesized. Mechanism of Seed Wettability-Manipulated Emulsion Interfacial Polymerization. To explore the mechanism of seed wettability-manipulated emulsion interfacial polymerization, we carefully observed the growth process of anisotropic Janus particles and heterogeneous nanoporous particles at different polymerization times using optical microscopy. In the hydrophobic seed (with size of 2.06 ± 0.04 μm) manipulated emulsion interfacial polymerization, before polymerization, homogeneous spherical oil microdroplets with the size of 5.06 ± 0.12 μm were observed (Figures 3a,b and S5a1). During the polymerization process, we observed a particle nucleus was first formed inside the oil microdroplet at 15 min (Figure S5a2), and then, the particle nucleus would move toward the O/W interface to initiate the polymerization of the hydrophilic monomer in the external water phase (Figure S5a3). Finally, anisotropic Janus particles were obtained (Figure S5a4), which was in accordance with our previous report.29 In the hydrophilic seed (with size of 2.04 ± 0.03 μm) manipulated emulsion interfacial polymerization, before polymerization, inhomogeneous spherical oil microdroplets with the size of 6.05 ± 0.08 μm were observed (Figures 3a,e and S5b1). Inside the oil microdroplet, many nanodroplets undergoing Brownian motion were observed (Movie S1). With the polymerization proceeding, the motion of these nanodroplets began to slow down, suggesting the polymerization of hydrophobic/hydrophilic monomers. Finally, heterogeneous nanoporous particles were obtained (Figure S5b2−b4). In our previous work, we have shown that the introduced noncross-linked hydrophobic PS seeds could be dissolved in St and DVB monomers to form free PS chains inside oil microdroplets.31 In this study, we speculated that these hydrophilic seeds would also be dissolved into free amphiphilic SPS chains (PS chains with −SO3H groups) inside oil microdroplets, like the surfactant. To verify our speculation, we respectively dissolved 2 mg of hydrophobic seeds and 2 mg of hydrophilic seeds in 4.0 mL of St monomer (stained by oil red), and then mixed with 1.0 mL of water to emulsify them by vigorously shaking. As shown in Figures 3c,d,f,g and S6, the mixtures of St−water with dissolved hydrophilic seeds could be emulsified to form stable W/O emulsions, while the mixtures of St−water with dissolved hydrophobic seeds could not be emulsified. During the dissolving process of hydrophilic seeds, because of strong hydrophilicity of −SO3H groups in the SPS chains, water molecules and the hydrophilic monomer would diffuse from the external water phase into oil microdroplets to form W/O/ W emulsion, inside which hydrophilic monomer−water nanodroplets stabilized by amphiphilic SPS chains could be
allowed the formation of spherical nanoporous particle (Figure 1g,h). The HRTEM image (Figure 1i) showed the heterogeneous nanoporous structure of the nanoporous particle. Interestingly, except for the outside surface of the hydrophilic PAA layer (with thickness of 58.8 ± 8.9 nm), the inside surface of the nanoporous particle could also be observed for the formation of the hydrophilic PAA layer. These results suggested that anisotropic Janus particles and spherical heterogeneous nanoporous particles could be produced accompanied with the variation of seed wettability in emulsion interfacial polymerization. Regulation of Seed Wettability. The wettability and interfacial activity of seeds were comprehensively investigated. Five kinds of seeds with different wettabilities were fabricated by controlling sulfonation time. The sulfonation reaction between hydrophobic PS seeds and sulfuric acid allowed the formation of hydrophilic −SO3H groups at the hydrophobic seed surface (Figure S1). As shown in Figures 2a−e and S2, after sulfonation, the size of these seeds had no significant change, and their surface became slightly rough with the increase of sulfonation time. We used a gel trapping technique34 to investigate the wettability of seeds at the oil− water interface. In general, a particle with three-phase CA (θ) lower 90° at the oil−water interface (measured through water) is defined as a hydrophilic particle, and a particle with threephase CA higher than 90° is defined as a hydrophobic particle.35,36 In our work, because the three-phase CA was measured through the oil phase, thus, a seed with three-phase CA lower 90° is defined as a hydrophobic seed, and a seed with three-phase CA higher than 90° is defined as a hydrophilic seed. The higher the three-phase CA is, the more hydrophilic the seed surface is. As shown in Figures 2f−j and S3, the threephase CA gradually increased from 45.4 ± 2.6° to 120.9 ± 2.2° with increasing sulfonation time (Figure 2k), suggesting that the seed wettability changed from hydrophobicity to hydrophilicity. As the sulfonation time increased, more hydrophilic −SO3H groups could be formed at the seed surface, as indicated by the zeta potential (Figure 2i), sulfur content analysis using XPS and sulfonation degree calculating33 (Figure 2m). The interfacial activity of seeds at the interface was measured by the pendant drop method. The concentration of seeds in water phase was 0.5 mg/mL. After a water droplet containing seeds was formed, the water/hexadecane interfacial tension started to decrease and finally reached a new equilibrium value. As shown in Figure 2n, compared with pure water/hexadecane, the seeds, regardless of hydrophobic seeds or hydrophilic seeds, could reduce interfacial tension. The interfacial tension was significantly reduced when seed wettability changed from hydrophobicity to hydrophilicity. These results demonstrated that the wettability and interfacial activity of seeds could be precisely regulated by merely controlling the sulfonation time. Precise Synthesis of Polymer Particles. We next investigated the influence of seed wettability on the topology and surface chemistry of obtained polymer particles in emulsion interfacial polymerization. As shown in Figures 2o−x and S4, the obtained polymer particles gradually shifted from anisotropic Janus particles to spherical heterogeneous nanoporous particles when the seed wettability changed from hydrophobicity to hydrophilicity. For the hydrophobic PS-0 (CA, 45.4 ± 2.6°) and SPS-1 (CA, 75.0 ± 2.1°) seed manipulated emulsion interfacial polymerization, the polymerization allowed the fabrication of anisotropic Janus particles D
DOI: 10.1021/acs.macromol.9b00199 Macromolecules XXXX, XXX, XXX−XXX
Article
Macromolecules
also be triggered at the W/O interface of nanodroplets. These nanodroplets would also make themselves as polymerization centers to trigger interfacial polymerization. Finally, heterogeneous nanoporous particles were synthesized. Generality of Seed Wettability-Manipulated Emulsion Interfacial Polymerization. The seed wettabilitymanipulated emulsion interfacial polymerization could be further expanded to the polymerization of various vinyl monomers. We used six kinds of hydrophilic monomers to demonstrate the generality of this polymerization. For hydrophobic seed-manipulated emulsion interfacial polymerization, anisotropic Janus particles with crescent shapes could be produced (Figure S7), similar with our previous work.29 For hydrophilic seed-manipulated emulsion interfacial polymerization, a large variety of heterogeneous nanoporous particles could be synthesized (Figure S8). Moreover, we also investigated the effect of monomer concentration of AA, St, and DVB on the topology of polymer particles. For hydrophobic seed-manipulated emulsion interfacial polymerization, anisotropic Janus particles with bread, hemisphere, crescent, and pistachio shapes were fabricated by controlling the concentration of hydrophilic/hydrophobic monomers (Figure S9). Also, for hydrophilic seed-manipulated emulsion interfacial polymerization, spherical heterogeneous nanoporous particles with different pore sizes could be obtained by tuning the concentration of hydrophilic/hydrophobic monomers (Figure S10). Anisotropic Janus particles and spherical heterogeneous nanoporous particles with tunable size could also be synthesized from nanoscale to microscale by controlling the size of hydrophobic and hydrophilic seeds (Figure S11). As shown in Figure 4, crescent-shaped Janus particles with the sizes of 0.90 ± 0.04, 2.96 ± 0.09, 4.07 ± 0.14 μm could be synthesized by varying the size of hydrophobic seeds (Figure 4a−d), while spherical heterogeneous nanoporous particles with sizes of 0.94 ± 0.05, 3.04 ± 0.05, 4.21 ± 0.08 μm were synthesized by changing the size of hydrophilic seeds (Figure 4e−h).
Figure 3. Mechanism of seed wettability-manipulated emulsion interfacial polymerization. (a) Schematic of hydrophobic and hydrophilic seed manipulated emulsion interfacial polymerization. The O/W droplet is formed by hydrophobic seed-manipulated emulsion interfacial polymerization, while the W/O/W droplet is formed by hydrophilic seed-manipulated emulsion interfacial polymerization because of osmotic pressure. (b) Optical microscope image of O/W microdroplet. (c,d) Photograph and optical microscope images show the St−water mixture with dissolved hydrophobic seeds cannot be emulsified to form emulsion. (e) Optical microscope image of W/O/W microdroplet. (f,g) Photograph and optical microscope images show the St−water mixture with dissolved hydrophilic seeds can be emulsified to form emulsion.
■
CONCLUSIONS In conclusion, we have demonstrated uniform polymer particles spanning from anisotropic Janus particles to heterogeneous nanoporous particles can be precisely synthesized by manipulating seed wettability in emulsion interfacial polymerization. The seed wettability is controlled by a sulfonation reaction between hydrophobic seeds and sulfuric acid. Along with the variation of seed wettability from hydrophobicity to hydrophilicity, the obtained polymer particles gradually shift from anisotropic Janus particles to spherical heterogeneous nanoporous particles. The hydrophobic seed-manipulated O/W emulsion interfacial polymerization fabricates anisotropic Janus particles, while the hydrophilic seed-manipulated W/O/W emulsion interfacial polymerization fabricates spherical heterogeneous nanoporous particles. This seed wettability-manipulated emulsion interfacial polymerization is a general approach, which is applicable to various hydrophobic/hydrophilic monomer pairs, allowing the fabrication of a large variety of polymer particles spanning from topologically and chemically anisotropic Janus particles to spherical heterogeneous nanoporous particles. We believe that our method provides a customizable way for the precise synthesis of particle materials spanning from isotropy to anisotropy, creating new opportunities in a wide variety of
formed. The diffusion process can be attributed to osmotic pressure (Π) inside the microdroplets,37,38 which is given by the following equation Π = nkBT
(1)
where n is the number of SPS chains, kB is Boltzmann constant, and T is the temperature. From eq 1, the osmotic pressure is proportional to the number of SPS chains. The number of SPS chains would increase with the increase of sulfonation time, leading to the rise of Π. The rise of Π allowed more water molecules and hydrophilic monomer to diffuse from the external water phase into oil microdroplets to form W/O/W emulsion. During polymerization, on the one hand, the polymerization could be triggered at the O/W interface of oil microdroplets. On the other hand, inside oil microdroplets, the polymerization could E
DOI: 10.1021/acs.macromol.9b00199 Macromolecules XXXX, XXX, XXX−XXX
Article
Macromolecules
Figure 4. Synthesis of anisotropic Janus particles and heterogeneous nanoporous particles with tunable size. (a−c) SEM images of anisotropic Janus particles with tunable size. (d) Average size of anisotropic Janus particles. (e−g) SEM images of spherical heterogeneous nanoporous particles with tunable size. (h) Average size of spherical heterogeneous nanoporous particles.
*E-mail:
[email protected] (S.W.).
applications, such as solid surfactants, blood purification, and biomacromolecule detection and separation.
■
ORCID
Yongyang Song: 0000-0003-1737-2428 Shutao Wang: 0000-0002-2559-5181
ASSOCIATED CONTENT
S Supporting Information *
Notes
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.macromol.9b00199.
■
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS The authors thank the financial support by the National Natural Science Foundation of China (21872158 and 21425314), National Key R&D Program of China (2018YFC1105301), and National Program for Special Support of Eminent Professionals.
Figure S1: XPS of hydrophobic PS-0 seeds and hydrophilic SPS-4 seeds; Figure S2: SEM images and the average particle size of seeds; Figure S3: SEM images of seeds with different wettabilities for the three-phase CA (θ) calculation; Figure S4: SEM images of polymer particles spanning from anisotropic Janus particles to spherical heterogeneous nanoporous particles; Figure S5: optical microscope images of the growth process of polymer particles at different polymerization times; Figure S6: photograph images and optical microscope images of the mixtures containing 1.0 mL of water and 4.0 mL of the St monomer (stained by oil red) with dissolved 2 mg of seeds; Figure S7: SEM images of anisotropic Janus particles with different surface charges fabricated by hydrophobic seed-manipulated emulsion interfacial polymerization; Figure S8: SEM images of spherical heterogeneous nanoporous particles with different surface charges fabricated by hydrophilic seed-manipulated emulsion interfacial polymerization; Figure S9: SEM images of anisotropic Janus particles fabricated by regulating the monomer concentration of AA, St, and DVB based on hydrophobic seedmanipulated emulsion interfacial polymerization; Figure S10: SEM images of spherical heterogeneous nanoporous particles fabricated by regulating the monomer concentration of AA, St, and DVB based on hydrophilic seed-manipulated emulsion interfacial polymerization; and Figure S11: SEM images of hydrophobic seeds and hydrophilic seeds with tunable size (PDF) Movie S1: Observation of nanodroplets undergoing Brownian motion (AVI)
■
REFERENCES
(1) Ugelstad, J.; Sö d erberg, L.; Berge, A.; Bergströ m , J. Monodisperse Polymer ParticlesA Step Forward for Chromatography. Nature 1983, 303, 95−96. (2) Song, Y.; Li, X.; Fan, J.B.; Kang, H.; Zhang, X.; Chen, C.; Liang, X.; Wang, S. Interfacially Polymerized Particles with Heterostructured Nanopores for Glycopeptide Separation. Adv. Mater. 2018, 30, 1803299. (3) Gref, R.; Minamitake, Y.; Peracchia, M.; Trubetskoy, V.; Torchilin, V.; Langer, R. Biodegradable Long-Circulating Polymeric Nanospheres. Science 1994, 263, 1600−1603. (4) Cui, J.; Richardson, J. J.; Björnmalm, M.; Faria, M.; Caruso, F. Nanoengineered Templated Polymer Particles: Navigating the Biological Realm. Acc. Chem. Res. 2016, 49, 1139−1148. (5) Liu, X.; Jin, X.; Ma, P. X. Nanofibrous Hollow Microspheres Self-Assembled from Star-Shaped Polymers as Injectable Cell Carriers for Knee Repair. Nat. Mater. 2011, 10, 398−406. (6) Repenko, T.; Rix, A.; Ludwanowski, S.; Go, D.; Kiessling, F.; Lederle, W.; Kuehne, A. J. C. Bio-Degradable Highly Fluorescent Conjugated Polymer Nanoparticles for Bio-Medical Imaging Applications. Nat. Commun. 2017, 8, 470. (7) Jiang, S.; Van Dyk, A.; Maurice, A.; Bohling, J.; Fasano, D.; Brownell, S. Design Colloidal Particle Morphology and Self-Assembly for Coating Applications. Chem. Soc. Rev. 2017, 46, 3792−3807. (8) Binks, B. P.; Rodrigues, J. A. Inversion of Emulsions Stabilized Solely by Ionizable Nanoparticles. Angew. Chem., Int. Ed. 2005, 44, 441−444. (9) Tu, F.; Lee, D. Shape-Changing and Amphiphilicity-Reversing Janus Particles with pH-Responsive Surfactant Properties. J. Am. Chem. Soc. 2014, 136, 9999−10006. (10) Ku, K. H.; Lee, Y. J.; Yi, G.R.; Jang, S. G.; Schmidt, B. V. K. J.; Liao, K.; Klinger, D.; Hawker, C. J.; Kim, B. J. Shape-Tunable
AUTHOR INFORMATION
Corresponding Authors
*E-mail:
[email protected] (J.-B.F.). *E-mail:
[email protected] (Z.G.). F
DOI: 10.1021/acs.macromol.9b00199 Macromolecules XXXX, XXX, XXX−XXX
Article
Macromolecules Biphasic Janus Particles as pH-Responsive Switchable Surfactants. Macromolecules 2017, 50, 9276−9285. (11) Wang, Y.; Wang, Y.; Breed, D. R.; Manoharan, V. N.; Feng, L.; Hollingsworth, A. D.; Weck, M.; Pine, D. J. Colloids with Valence and Specific Directional Bonding. Nature 2012, 491, 51−55. (12) Gröschel, A. H.; Walther, A.; Löbling, T. I.; Schacher, F. H.; Schmalz, H.; Müller, A. H. E. Guided Hierarchical Co-Assembly of Soft Patchy Nanoparticles. Nature 2013, 503, 247−251. (13) Walther, A.; Müller, A. H. E. Janus Particles: Synthesis, SelfAssembly, Physical Properties, and Applications. Chem. Rev. 2013, 113, 5194−5261. (14) Liang, F.; Zhang, C.; Yang, Z. Rational Design and Synthesis of Janus Composites. Adv. Mater. 2014, 26, 6944−6949. (15) Bradley, L. C.; Stebe, K. J.; Lee, D. Clickable Janus Particles. J. Am. Chem. Soc. 2016, 138, 11437−11440. (16) Qu, J.B.; Liu, Y.; Liu, J.Y.; Huan, G.S.; Wei, S.N.; Li, S.H.; Liu, J.G. One-Pot Synthesis of Bimodal Gigaporous Polystyrene Microspheres with Hydrophilic Surfaces. Macromolecules 2018, 51, 4085− 4093. (17) Ku, K. H.; Shin, J. M.; Klinger, D.; Jang, S. G.; Hayward, R. C.; Hawker, C. J.; Kim, B. J. Particles with Tunable Porosity and Morphology by Controlling Interfacial Instability in Block Copolymer Emulsions. ACS Nano 2016, 10, 5243−5251. (18) Tung, H.Y.; Guan, Z.Y.; Liu, T.Y.; Chen, H.Y. Vapor Sublimation and Deposition to Build Porous Particles and Composites. Nat. Commun. 2018, 9, 2564. (19) Smith, W. V. The Kinetics of Styrene Emulsion Polymerization1a. J. Am. Chem. Soc. 1948, 70, 3695−3702. (20) Ugelstad, J.; El-Aasser, M. S.; Vanderhoff, J. W. Emulsion Polymerization: Initiation of Polymerization in Monomer Droplets. J. Polym. Sci., Polym. Lett. Ed. 1973, 11, 503−513. (21) Okubo, M.; Fujibayashi, T.; Yamada, M.; Minami, H. MicronSized, Monodisperse, Snowman/Confetti-Shaped Polymer Particles by Seeded Dispersion Polymerization. Colloid Polym. Sci. 2005, 283, 1041−1045. (22) Kim, J.-W.; Larsen, R. J.; Weitz, D. A. Uniform Nonspherical Colloidal Particles with Tunable Shapes. Adv. Mater. 2007, 19, 2005− 2009. (23) Sheu, H. R.; El-Aasser, M. S.; Vanderhoff, J. W. Phase Separation in Polystyrene Latex Interpenetrating Polymer Networks. J. Polym. Sci., Part A: Polym. Chem. 1990, 28, 629−651. (24) Mock, E. B.; De Bruyn, H.; Hawkett, B. S.; Gilbert, R. G.; Zukoski, C. F. Synthesis of Anisotropic Nanoparticles by Seeded Emulsion Polymerization. Langmuir 2006, 22, 4037−4043. (25) Yu, X.; Sun, Y.; Liang, F.; Jiang, B.; Yang, Z. Triblock Janus Particles by Seeded Emulsion Polymerization. Macromolecules 2019, 52, 96−102. (26) Kim, J.W.; Larsen, R. J.; Weitz, D. A. Synthesis of Nonspherical Colloidal Particles with Anisotropic Properties. J. Am. Chem. Soc. 2006, 128, 14374−14377. (27) Park, J.G.; Forster, J. D.; Dufresne, E. R. High-Yield Synthesis of Monodisperse Dumbbell-Shaped Polymer Nanoparticles. J. Am. Chem. Soc. 2010, 132, 5960−5961. (28) van Ravensteijn, B. G. P.; Kamp, M.; van Blaaderen, A.; Kegel, W. K. General Route toward Chemically Anisotropic Colloids. Chem. Mater. 2013, 25, 4348−4353. (29) Fan, J.B.; Song, Y.; Liu, H.; Lu, Z.; Zhang, F.; Liu, H.; Meng, J.; Gu, L.; Wang, S.; Jiang, L. A General Strategy to Synthesize Chemically and Topologically Anisotropic Janus Particles. Sci. Adv. 2017, 3, e1603203. (30) Song, Y.; Zhou, J.; Fan, J.B.; Zhai, W.; Meng, J.; Wang, S. Hydrophilic/Oleophilic Magnetic Janus Particles for the Rapid and Efficient Oil-Water Separation. Adv. Funct. Mater. 2018, 28, 1802493. (31) Fan, J.B.; Liu, H.; Song, Y.; Luo, Z.; Lu, Z.; Wang, S. Janus Particles Synthesis by Emulsion Interfacial Polymerization: Polystyrene as Seed or Beyond? Macromolecules 2018, 51, 1591−1597. (32) Goodall, A. R.; Wilkinson, M. C.; Hearn, J. Mechanism of Emulsion Polymerization of Styrene in Soap-Free Systems. J. Polym. Sci., Polym. Chem. Ed. 1977, 15, 2193−2218.
(33) Paunov, V. N. Novel Method for Determining the Three-Phase Contact Angle of Colloid Particles Adsorbed at Air−Water and Oil− Water Interfaces. Langmuir 2003, 19, 7970−7976. (34) Binks, B. P.; Isa, L.; Tyowua, A. T. Direct Measurement of Contact Angles of Silica Particles in Relation to Double Inversion of Pickering Emulsions. Langmuir 2013, 29, 4923−4927. (35) Schrade, A.; Landfester, K.; Ziener, U. Pickering-Type Stabilized Nanoparticles by Heterophase Polymerization. Chem. Soc. Rev. 2013, 42, 6823−6839. (36) Yuan, Q.; Yang, L.; Wang, M.; Wang, H.; Ge, X.; Ge, X. The Mechanism of the Formation of Multihollow Polymer Spheres through Sulfonated Polystyrene Particles. Langmuir 2009, 25, 2729− 2735. (37) Mezzenga, R.; Folmer, B. M.; Hughes, E. Design of Double Emulsions by Osmotic Pressure Tailoring. Langmuir 2004, 20, 3574− 3582. (38) Bae, J.; Russell, T. P.; Hayward, R. C. Osmotically Driven Formation of Double Emulsions Stabilized by Amphiphilic Block Copolymers. Angew. Chem., Int. Ed. 2014, 53, 8240−8245.
G
DOI: 10.1021/acs.macromol.9b00199 Macromolecules XXXX, XXX, XXX−XXX
