Preparation and characterization of poly(sodium 4-styrenesulfonate)-decorated hydrophilic carbon black by one-step in situ ball milling

Colloids and Surfaces A: Physicochem. Eng. Aspects 443 (2014) 135–140

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Preparation and characterization of poly(sodium 4-styrenesulfonate)-decorated hydrophilic carbon black by one-step in situ ball milling Peng-Wei Shi, Qiu-Ying Li, You-Chen Li, Chi-Fei Wu ∗ Polymer Alloy Laboratory, Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, PR China

h i g h l i g h t s

g r a p h i c a l

• Highly hydrophilic CB nanoparticles

Natural sedimentation in water of (a) 0 day after (b) 30 min after (c) 15 days after (d) inversed bottle of PCBs Ball milling without PSS could only make large CB aggregations loose, leading to the sedimentation of BCBs to the bottom slower than the pristine CB. With the existence of the PSS, the modified CB exhibited excellent dispersity and stability in water for at least 15 days.

were prepared by one-step in situ ball milling. • The resulting PCBs exhibited an extraordinary stability in water. • The internal structure of CB could be seriously changed with the existence of PSS. • Large CB aggregations could be broken into small pieces with the existence of PSS.

a r t i c l e

i n f o

Article history: Received 4 June 2013 Received in revised form 16 October 2013 Accepted 28 October 2013 Available online 5 November 2013 Keywords: Poly(sodium 4-styrenesulfonate) Ball milling Hydrophilic Carbon black

a b s t r a c t

a b s t r a c t A one-step method for preparing poly(sodium 4-styrenesulfonate) (PSS)-decorated hydrophilic carbon black (CB), via in situ peeling of large CB aggregates into small pieces at room temperature, was investigated. The Raman spectroscopy results indicated that ball milling could only break large CB aggregates into small pieces but without changing its structure, while the structure of CB was significantly changed with the existence of PSS. The results of Fourier transform infrared spectroscopy, transmission electron microscope, energy dispersive X-ray spectroscopy and natural sedimentation experimental all showed that the CB was successfully coated by PSS and yielded an excellent stability in water. The backbones of PSS were coated onto the CB surface under strong ␲–␲ interactions with an encapsulation ratio of 12.7 wt%. The resulting PSS-decorated CB displayed an extraordinary stability in water with an average size of 221 nm and zeta potential of −33.8 mV, far outstripping the pristine CB and ball milled CB without PSS. © 2013 Elsevier B.V. All rights reserved.

1. Introduction Carbon black (CB) is structurally complex particles and composed of irregularly shaped aggregates ranging in size from tens of

∗ Corresponding author. Tel.: +86 21 64251844; fax: +86 21 64252569. E-mail address: [email protected] (C.-F. Wu). 0927-7757/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.colsurfa.2013.10.060

nanometers to several hundred nanometers [1]. CB also possesses excellent chemical stability, heat resistance, electrical conductivity, darkness, and safe features. So CB has been widely used as a reinforcing agent in the rubber industry, as filler in polymeric matrixes, as an electrode for supercapacitors and pigment in modern print technologies [2–8]. However, most of these applications require the good dispersibility of CB, and bare CB aggregates aggressively owing to its extremely large surface-area/particle-size ratio,

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which leading to the poor dispersibility of CB in most solvents, especially in aqueous solution [9], thus the practical applications of CB have been severely hindered. As the good dispersion of CB in water is required in many different application fields, the surface modification for improving its hydrophilicity by a low cost and environment-friendly method is of great significance and in urgent needs. Until now, various methods have been reported for the surface modification and functionalization to enhance the hydrophilicity of CB, including oxide modification, graft modification, surface coating, and dispersant modification [1,10–18]. Zhu et al. fabricated dopamine encapsulated hydrophilic CB through oxide polymerization [1]. Xue et al. studied the oxidation mechanism of CB by HNO3 [11]. Li et al. studied the effect of ultrasonic on the structure of CB, and successfully synthesized PVA-g-CB by ultrasonic method [12]. He et al. synthesized PSS-g-CB by using sodium 4-styrenesulfonate (NASS) monomer in HAAKE [13]. Paredes et al. enhanced the hydrophilicity of CB by plasma treatment [14]. Liu et al. synthesized hydrophilic DMAEMA-g-CB by grafting 2-DMAEMA from functionalized CB using atom transfer radical polymerization (ATRP) [15]. However, conventional surface modification technologies, such as oxide modification and dispersant modification have some drawbacks, like weak stirring capacities, uneven dispersion between agent and materials, and, in particular, lacking of reaction foundation [16,17]. Moreover, the preparation of hydrophilic CB by Ultrasonic, Haake and ATRP all required harsh conditions such as high-demand temperature, accurate time and precise reactant ratio control, leading to the hazardous, laborious and time consuming preparation process. Therefore, the development of an efficiency and environmental-friendly strategy for the surface hydrophilic modification of CB is of great importance. Ball milling, which could activate the CB in the near surface region where solids come into contact with each other [18–20], is an effective surface modification method that could provide better results than conventional methods by ultrafine grinding. Furthermore, due to the changeable Gibbs free energy of reactions triggered by the large active particles, the chemical activation parameters and sites of polymer composites can be modified by the ball milling processing. Therefore, ball milling has been applied to a variety of organic syntheses with high-speed reactions and largescale productions by controlling the parameters such as ball milling time and rotating speed [21,22]. In the previous study, the one step ball milling method was used to synthesis polymer-functionalized graphene nanocomposites [20], and here we report the preparation of PSS-decorated highly hydrophilic CB by this method. The as-prepared CB particles were coated by PSS under the binding force of strong ␲–␲ interactions [23–25]. The PSS chains, which are rich of highly hydrophilic sulfonic acid groups, would coat onto the CB surface and thus prevented the CB nanoparticles from aggregating and led to an extraordinary stability than the original CB and ball milled CB without PSS. This paper provides an environmental-friendly method for preparing excellent hydrophilic CB with terminal sulfonic acid groups.

2.2. Preparation of PSS-decorated CB CB was dried for 24 h at 105 ◦ C under vacuum before using. A planetary ball milling (QM-1SP2, Nanjing University instrument plant) was used in this study. Firstly, the grinding balls with good proportion were filled into the grinding bowl, which took up at least one-third of its volume to reduce the wear between grinding balls and bowl. Then put 5.0 g CB, 5.0 g PSS into the grinding bowl. To ensure that the samples were effectively grounded, 200 ml deionized water was filled but not past three quarters of the bowl volume. The closed grinding bowl was then placed into the planetary ball mill and secured using the “safe lock”. The counter weight was adjusted based on the weight of the bowl and samples to reduce the vibration of the milling operation [26]. Finally, the modified CB was separated from aqueous solution by ultra-centrifuge (SORVALL RC6+ Centrifuge, American) at 20,000 rpm for 30 min. As comparison, ball milled CB without PSS was also prepared to study the mechanism of ball milling on the evolution of CB structure. To simplify the following discussion, the ball milled CB without PSS treated for 18 and 36 h were abbreviated as BCB-1 and BCB-2, respectively. Similarly, the ball milled CB with PSS treated for 18 and 36 h were named as PCB-1 and PCB-2, respectively. 2.3. Characterizations Raman spectra were recorded using an inVia + Reflex from Renishaw, UK. A He–Ne laser at an excitation wavelength of 633 nm was used to accurately profile the contribution of D bands (∼1340), G bands (∼1600) and A bands (1550) of CB [11]. Generally, the D band is attribute to the presence of defects (sp3 carbons, vacancies, foreign atoms, etc.), while the G band is considered to be an in-plane bond-stretching motion of sp2 -hybridised C atoms [27,28], and the A band is ascribed to amorphous carbon [29]. A linear background was subtracted. Then, the Lorentzian-shaped D and G bands and the broad, Gaussian-shaped A band were used to fit the spectra [29]. The ratio of G and D bands can be used to approximate the microcrystalline size (La) of the CB particles [11,30]. Fourier transform infrared spectroscopy (FTIR) spectra were obtained by a Nicolet 5700 spectrometer under ambient conditions. The spectra were obtained in the wave number range from 600 to 4000 cm−1 . The elements composition and surface morphologies of CB particles were observed by energy dispersive X-ray spectroscopy (EDS) (QUANTAX 400-30, Bruker AXS GmbH) and transmission electron microscope (TEM) (JEM-2010, Hitachi, Japan), respectively. The CB samples were ultrasonically dispersed in distilled water, and then a drop of the solution was deposited on a copper screen for TEM characterization. The particle size distribution and zeta potential of CB was measured by a laser particle analyzer (Zetasize Nano-ZEN3600, Malvern, Great Britain). The CB samples were dispersed in distilled water with ultrasonic for 30 min, and then the dispersions (0.005 wt% CB) were laid up in the laser particle analyzer. The thermal gravimetric analysis (TGA) of CB was carried out with TGA analyzer (STA449 F3 Jupiter, NETZSCH, German). Each sample weighing about 10 mg was heated from room temperature to 800 ◦ C at a rate of 10 ◦ C min−1 in nitrogen atmosphere.

2. Experimental 3. Results and discussion 2.1. Materials CB, in the form of Mogul-L, was obtained from Cabot Co. PSS was purchased from Nanjing Searchbio Tech. Co. Ltd., with the molecular weight of 200,000. Deionized water was also used in this study. All the materials were used without further purification.

Raman spectroscopy, which is an useful method to determine the structure of carbon materials, was used to study the evolution of CB structure during ball milling process [31]. Fig. 1 shows the Raman spectra acquired from CB, BCBs (BCB-1 and BCB-2) and PCBs (PCB-1and PCB-2) samples. Each spectrum corresponds to

P.-W. Shi et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 443 (2014) 135–140

Fig. 1. Raman spectra of pristine CB, BCBs and PCBs. The spectra are offset for clarity.

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Fig. 3. FTIR spectra of pristine CB and PCBs.

integrated intensity ratio IG /ID and the microcrystalline planar size La show a positive proportional behavior, using the empirical formula found by Tuinstra and Koenig [30], La (nm) = 4.35

Fig. 2. Raman spectrum of pristine CB with the corresponding curve fitted bands.

the average of five spectra, so it could highly represent for each sample. Compared with the untreated CB, which exhibits broad and overlapping peaks, the Raman spectra for BCBs did not have noticeable difference. However, the PCBs spectra show more overlapping peaks. The different behavior of the BCBs and the PCBs can be explained by the differences in their structures. An example spectrum for pristine CB with three band fits used for quantitative spectra analysis is shown in Fig. 2, and the fitting results are summarized in Table 1. The full width at half maximum (FWHM) of the D band and the A band intensity are the spectroscopic parameters that can provide information about the relative abundance and structural order of graphic and molecular carbon and yield the greatest amount of information about the chemical structure. Moreover, the D bandwidth has been found to exhibit a nearly linear negative correlation to the amount of apparent elemental carbon in different types of carbonaceous materials [11,32].It is generally accepted that the dependence between the

IG ID

where ID and IG are the integrated intensities of the D and G bands, respectively. The crystal size La, calculated from Eq. (1) is also added in Table 1. As expected, the La of the BCBs are only slightly lower than the pristine CB, while the La of PCBs shows a decrease from 0.66 to 0.50 nm. The analysis showed above indicated that the bare ball milling had only a little influence on the internal structure of CB. However, for the PCBs, the G peaks show a blue shift after ball milling and the corresponding FWHMs decrease, while FWHMs of the D bands increase. The results above indicate that CB with an undeveloped crystallographic structure was easily damaged during the ball milling process with the existence of PSS, remaining the more perfect crystallographic structure. This also leads to the blue shift of the G bands and the decrease of FWHMs. Moreover, under the force fields provided by the grinding balls, the large CB aggregates were broken into small pieces, leading to the PSS chains coated onto CB surface. The coated are increased the amount of foreign carbon, i.e. the intensities of D bands increased, leading to the increase of FWHM for D bands. Under the double effect mentioned above that the microcrystalline planar size La calculated by the formula (1) are definitely small than the pristine CB and BCBs. Furthermore, the intensity of A bands decreased, which was responsible for the strong overlap of G and D peaks, and the intensity of D bands increased, due to the increasing amount of six-fold aromatic ring near the edge. FTIR spectra of CB, PCB-1 and PCB-2 are shown in Fig. 3. All of the three samples exhibit a distinctive absorption band at 1596 cm−1 , which associates with the aromatic C C stretching vibration. Compared with these bands at 1596 cm−1 , the intensity of absorption peaks gradually increased for CB, PCB-1, and PCB-2, indicating the increasing intensity of the phenol structure of PSS coating onto the

Table 1 Raman spectroscopic parameters obtained after curve fitting the experimental spectra by using two Lorentzian bands (D and G) and a Gaussian band (A). Samples

G band (cm−1 )

CB BCB-1 BCB-2 PCB-1 PCB-2

1594 1594 1594 1595 1605

Position ± ± ± ± ±

2 1 1 1 1

D band (cm−1 ) FWHM 55 57 57 50 48

± ± ± ± ±

3 3 1 1 2

Position 1350 1350 1350 1351 1358

± ± ± ± ±

1 1 1 1 1

A band (cm−1 ) FWHM 206 207 208 212 214

± ± ± ± ±

3 4 1 1 3

Position 1556 1558 1555 1560 1564

± ± ± ± ±

3 1 2 1 1

La (nm) FWHM 147 145 150 137 135

± ± ± ± ±

6 2 4 1 1

0.66 0.65 0.68 0.53 0.50

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Fig. 6. TEM images of (a) pristine CB and (b) PCB-2.

Na and S, and an enhanced O peak, which must originate from the PSS chains. The encapsulation ratio is calculated by the following equation Fig. 4. EDS spectra of (a) pristine CB and (b) PCB-2.

ω= CB surface. The new absorption bands at 1174, 1122 and 1034 cm−1 noted in the spectrum of PCB-1and PCB-2 are the character absorption bands of PSS, and the peak intensity increased with the ball milling time, indicating that the amount of PSS that coated onto the CB surface was gradually increased. EDS analyses of the pristine CB and PCB-2 are shown in Fig. 4. As shown in Fig. 4(a), the pristine CB is composed of large amounts of C (92.16 wt%) and a small percent of O (7.18 wt%), and no other elements were observed. Comparing Fig. 4(a) with Fig. 4(b), the EDS spectrum of PCB-2 (Fig. 4(b)) reveals two distinctive peaks, i.e.

Fig. 5. TGA curves of pristine CB, PCB-1, PCB-2 and PSS.

ω1 × M3 × 100% 3M1

(1)

ω2 × M3 × 100% M2

(2)

or ω=

where ω is the encapsulation of PCB-2, ω1 and ω2 are the weight percent of Na and S in PCB-2. M1 and M2 are the relative atomic weight of Na and S, in addition, M3 is the molecular weight of the NASS monomer. The encapsulation ratio of PCB-2 calculates by the weight percent of Na and S are 12.7 and 11.7 wt%, respectively, which is consistence with the TGA result in the following discussion.

Fig. 7. Effect of ball milling time on particle size distribution and zeta potential.

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Fig. 8. Natural sedimentation pristine CB, BCBs and PCBs in water of (a) 0 day after, (b) 30 min after, (c) 15 days after, and (d) the inversed bottle of PCBs.

The thermal stability and encapsulation ratio of the CB was evaluated by TGA. Fig. 5 shows the TGA programs of pristine CB, PCB-1, PCB-2 and pure PSS. The PSS exhibited three distinguished weight loss process. The onset of the first weight loss is at about 100 ◦ C, owing to the elimination of moisture and other thermal volatile residuals. The last two losses begin at about 400 ◦ C correspond to the decomposition temperature of PSS, i.e. the sulfonic acid groups and [ CH2 CH2 ] segments in the PSS chains. The weight loss of the PSS homopolymer is about 40% up to 600 ◦ C, indicating that the PSS homopolymer has excellent thermal stability. The encapsulation ratio of PCBs could be calculated by the following formulation, ω=

WCB − WPCBs × 100% 1 − WPSS

(3)

where WCB , WPSS and WPCBs are the residual weight of pristine CB, PCBs and PSS below 600 ◦ C, respectively. As calculated by the formula (3), the encapsulation ratio of PCB-1 and PCB-2 are 11.3 and 14.9 wt%, respectively. This result of PCB-2 is consistent with the EDS analysis discussed above, and the TGA results are slightly higher may attributed to the water absorption on the CB surface. The morphology and dispersion of CB was studied by TEM as shown in Fig. 6. The unmodified CB particles tend to aggregate as can be seen from Fig. 6(a), i.e. large amounts of CB primary particles aggregate together and the size ranging from tens of nanometers to several hundred nanometers. In comparison, because large agglomerates were divided into small agglomerates during the ball milling process, the PCB-2 dispersed in water homogeneously, with only few CB primary particles aggregate together (Fig. 6(b)). Comparing the TEM images of PCB-2 (Fig. 6(b)) with that of the pristine CB (Fig. 6(a)), an increase can be seen in the particle size after PSS coating and a clear thin layer of PSS layer can be observed on the PCB-2 particles. The abundant hydrophilic groups introduced by PSS on the CB surface made the particles disperse in water homogeneously. Furthermore, the PSS layer around the CB nanoparticles acted as the steric hindrance and prevents the CB nanoparticles from aggregating. The above phenomena all suggested that the CB nanoparticles were well encapsulated by the PSS and agglomerated less after the encapsulation. Usually, nanoparticles are prone to aggregate for high surface energy, but the aggregation can be restrained and small aggregations are expected to form if the nanoparticles are hydrophilic [1]. A laser particle analyzer was used to analyze the particle size distribution and zeta potential of the PCBs for different ball milling times. As shown in Fig. 7, with the increase of the ball milling time, the average diameter of PCBs decreased from 268 to 221 nm and the zeta potential increased from −22.3 to −36.8 mV. The abundant hydrophilic groups introduced by the PSS coated onto the

CB surface increased the repulsion between the CB particles and thus leaded to the increase of zeta potential. Moreover, the benzene ring structure introduced by PSS chains could also prevent the CB from aggregating. Under the double effect of electrostatic repulsion and steric hindrance, the highly hydrophilic CB nanoparticles were prepared. The stability and dispersity of PCBs nanoparticles in aqueous solution were also evaluated by natural sedimentation experimental. For comparison, the pristine CB, BCBs and PCBs were placed under the same conditions. It can be seen from Fig. 8(b) that the pristine CB settled to the bottom quickly only after 30 min, and the BCBs and PCBs did not show apparent change. However, after 15 days, the BCBs completely settled to bottom. This phenomenon may attribute to that the ball milling break the large aggregates of CB into small pieces, leading to the slower sedimentation of BCBs to the bottom. In contrast, the PCBs nanoparticles showed an excellent hydrophilicity and yielded a stable colloidal dispersion in water. As shown in Fig. 8(c), the PCBs nanoparticles form a homogeneous dispersion in water and keep stable for at least 15 days before any noticeable flocculation, and even the bottle was inversed, there was no precipitates staying on the bottom (Fig. 8(d)). These results further indicated that the CB encapsulated by PSS having excellent stability in water.

4. Conclusions The poly(sodium 4-styrenesulfonate)-decorated highly hydrophilic carbon black has been successfully prepared by one-step in situ ball milling method at room temperature. The results of Raman indicated that under the force fields provided by grinding balls, the large CB aggregates were broken into small pieces, leading to the coating of PSS chains onto the CB surface through strong ␲–␲ interactions. The results of FTIR, TEM and EDS all showed that the PSS chains coated onto the CB surface successfully and with an encapsulation ratio of 12.7 wt%, which were consistence with the TGA results. Furthermore, the backbones of PSS coated onto the surface of CB could effectively prevent the CB particles from aggregating, thus leading to the extraordinary stability of the PSS-decorated CB with an average size of 221 nm and zeta potential up to −33.8 mV according to the test results of laser particle analyzer. The natural sedimentation experiment also showed that the PCBs did not have distinctive sedimentation even after 15 days. A controllable and environment-friendly method was demonstrated in this work for the preparation of highly hydrophilic CB nanoparticles, and it could also be expanded to other fields.

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Acknowledgements The authors sincerely acknowledge the National Key Technology R&D Program of China (2012BAD32B01) and the Outstanding Technology Foregoer Plan of Shanghai (12XD1420400).

[15]

[16]

References

[17]

[1] L.J. Zhu, Y.L. Lu, Y.Q. Wang, L.Q. Zhang, W.C. Wang, Preparation and characterization of dopamine-decorated hydrophilic carbon black, Appl. Surf. Sci. 258 (2012) 5387–5393. [2] J. Yan, T. Wei, B. Shao, F.Q. Ma, Z.G. Fan, M.L. Zhang, Electrochemical properties of graphene nanosheet/carbon black composites as electrodes for supercapacitors, Carbon 48 (2010) 1731–1737. [3] M.S. Mauter, M. Elimelech, Environmental applications of carbon-based nanomaterials, Environ. Sci. Technol. 42 (2008) 5843–5859. [4] K.U. Lee, K.J. Park, O.J. Kwon, J.J. Kim, Carbon sphere as a black pigment for an electronic paper, Curr. Appl. Phys. 13 (2013) 419–424. [5] Y.L. Lin, L.S. Wang, A.Q. Zhang, H.J. Hu, Y.Y. Zhou, Y. Lin, Particle size distribution, mixing behavior, and mechanical properties of carbon black (high-abrasion furnace)-filled powdered styrene butadiene rubber, J. Appl. Polym. Sci. 94 (2004) 2494–2508. [6] N. Probst, E. Grivei, Structure and electrical properties of carbon black, Carbon 40 (2002) 201–205. [7] A.G. Pandolfo, A.F. Hollenkamp, Carbon properties and their role in supercapacitors, J. Power Sources 157 (2006) 11–27. [8] F. Liang, N. Li, X.K. Li, W. Yan, Effect of the addition of carbon black and carbon nanotubes on the structure and oxidation resistance of pyrolysed phenolic carbons, New Carbon Mater. 27 (2012) 283–287. [9] J.J. Yang, B.T. Tang, W.Z. Qiu, S.F. Zhang, Controlled dispersion and precipitation of carbon black by a pH-responsive polyampholyte containing amino groups and aryl sulfonates, Carbon 50 (2012) 5621–5624. [10] T. Sritapunya, S. Jairakdee, T. Kornprapakul, S. Somabutr, K. Siemanond, t.K. Bunyakia, Adsorption of surfactants on carbon black and paper fiber in the presence of calcium ions, Colloids Surf. A 389 (2011) 206–212. [11] P.F. Xue, J. Gao, Y.B. Bao, J.B. Wang, Q.Y. Li, C.F. Wu, An analysis of microstructural variations in carbon black modified by oxidation or ultrasound, Carbon 49 (2011) 3346–3355. [12] Q.Y. Li, X.L. Zhang, G.Z. Wu, S.A. Xu, C.F. Wu, Sonochemical preparation of carbon nanosheet from carbon black, Ultrason. Sonochem. 14 (2007) 225–228. [13] X.L. He, Z. Peng, N. Yu, J.J. Han, C.F. Wu, Poly(sodium 4-styrenesulfonate) modified carbon nanoparticles by a thermo-mechanical technique and its reinforcement in natural rubber latex, Compos. Sci. Technol. 68 (2008) 3027–3032. [14] J.I. Paredes, M. Gracia, A. Martínez-Alonso, J.M.D. Tascón, Nanoscale investigation of the structural and chemical changes induced by oxidation on carbon

[18] [19] [20]

[21]

[22]

[23]

[24]

[25] [26] [27]

[28] [29]

[30] [31]

black surfaces: a scanning probe microscopy approach, J. Colloid Interface Sci. 288 (2005) 190–199. T.Q. Liu, S.J. Jia, T. Kowalewski, K. Matyjaszewski, Water-dispersible carbon black nanocomposites prepared by surface-initiated atom transfer radical polymerization in protic media, Macromolecules 39 (2006) 548–556. K. Kamegawa, K. Nishikubo, H. Yoshida, Oxidative degradation of carbon blacks with nitric acid (I)-changes in pore and crystallographic structures, Carbon 36 (1998) 433–441. F. Tiarks, K. Landfester, M. Antonietti, Encapsulation of carbon black by miniemulsion, Macromol. Chem. Phys. 202 (2001) 51–60. E. Yo˘gurtcuo˘glu, M. Uc¸urum, Surface modification of calcite by wet-stirred ball milling and its properties, Powder Technol. 214 (2011) 47–53. U. Dusek, G.P. Reischl, R. Hitzenberger, CCN activation of pure and coated carbon black particles, Environ. Sci. Technol. 40 (2006) 1223–1230. H. Wu, W.F. Zhao, H.W. Hu, G.H. Chen, One-step in situ ball milling synthesis of polymer-functionalized graphene nanocomposites, J. Mater. Chem. 21 (2011) 8626–8632. F. Stenger, S. Mende, J. Schwedes, W. Peukert, The influence of suspension properties on the grinding behavior of alumina particles in the submicron size range in stirred media mills, Powder Technol. 156 (2005) 103–110. T. Sritapunya, S. Jairakdee, T. Kornprapakul, S. Somabutr, K. Siemanond, K. Bunyakiat, Adsorption of surfactants on carbon black and paper fiber in the presence of calcium ions, Colloids Surf. A 389 (2011) 206–212. K. Katsumi, N. Keiko, K. Masaya, A. Yoshio, Y. Hisayoshi, Aqueous-phase adsorption of aromatic compounds on water-soluble nanographite, Colloids Surf. A 254 (2005) 31–35. H.F. Wang, T. Troxler, A.G. Ye, H.L. Dai, Adsorption at a carbon black microparticle surface in aqueous colloids probed by optical second-harmonic generation, J. Phys. Chem. C 111 (2007) 8708–8715. S.C. Wong, E.M. Sutherland, F.M. Uhl, Materials processes of graphite nanostructured composites using ball milling, Mater. Manuf. Process. 21 (2006) 159–166. A.C. Ferrari, J. Robertson, Interpretation of Raman spectra of disordered and amorphous carbon, Phys. Rev. B 61 (2000) 14096–14106. E.R. Talaty, S. Raja, V.J. Storhaug, A. Dölle, W.R. Carper, Raman and Infrared Spectra and ab initio calculations of C2-4 MIM imidazolium hexafluorophosphate ionic liquids, J. Phys. Chem. B 108 (2004) 13177–13184. N. Larouche, B.L. Stansfield, Classifying nanostructured carbons using graphitic indices derived from Raman spectra, Carbon 48 (2010) 620–629. T.W. Zerda, W. Xu, A. Zerda, Y. Zhao, R.B. Von Dreele, High pressure Raman and neutron scattering study on structure of carbon black particles, Carbon 38 (2000) 355–361. L. Lu, V. Sahajwalla, C. Kong, D. Harris, Quantitative X-ray diffraction analysis and its application to various coals, Carbon 39 (2001) 1821–1833. N.P. Ivleva, U. Mckeon, R. Niessner, U. Pöschl, Raman microspectroscopic analysis of size-resolved atmospheric aerosol particle samples collected with an ELPI: Soot, Humic-Like Substances, and Inorganic compounds, Sci. Tech. 41 (2007) 655–671.