Surface Modification of Attapulgite Nanorods with Nitrile Butadiene

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Materials and Interfaces

Surface modification of attapulgite nanorods with nitrile butadiene rubber via thiol-ene interfacial click reaction: grafting or crosslinking Changou Pan, and Peng Liu Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.8b00094 • Publication Date (Web): 22 Mar 2018 Downloaded from http://pubs.acs.org on March 22, 2018

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Industrial & Engineering Chemistry Research

Surface Modification of Attapulgite Nanorods with Nitrile Butadiene Rubber via Thiol-ene Interfacial Click Reaction: Grafting or Crosslinking Changou Pan,a Peng Liua,b,* a

State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China

b

Key Laboratory of Clay Mineral Applied Research of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China

AUTHOR INFORMATION *Corresponding Author. E-mail: [email protected]. Tel./Fax: 86-931-8912582.

* Corresponding author at: State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China. Fax: +86 931 8912582. E-mail address: [email protected] (P. Liu).

ACS Paragon Plus Environment

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Abstract A versatile approach was developed for the preparation of crosslinked attapulgite (ATP)-nitrile butadiene rubber (NBR) nanocomposites or NBR grafted ATP nanorods, by facile adjusting the feeding ratio between the butadiene-based rubbers and the thiol-modified attapulgite (ATP-SH) nanorods in a facile thermal-triggered thiol-ene interfacial click reaction. The modified products with different feeding ratios between the ATP-SH and NBR were characterized with FT-IR, TGA and TEM techniques. The results indicated that the crosslinked ATP-NBR nanocomposites could be produced via the thiol-ene interfacial click reaction with excess NBR, while the NBR grafted ATP nanorods could be synthesized via the reaction with excess ATP-SH nanorods. Based on the results, a possible mechanism and potential applications were proposed.

Keywords: Surface modification; thiol-ene interfacial click reaction; attapulgite nanorods; nitrile butadiene rubber; grafting; crosslinking


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INTRODUCTION Clays have attracted more and more interest in the polymer-based nanocomposites in the last decades, owing to their high natural abundance and the excellent comprehensive performance of the nanocomposites.1 However, the surface polarity still remains a roadblock, restricting their dispersibility in the polymeric matrices. So the clay nanomaterials should be surface-modified,2 especially grafting polymers,3 before mixing with the polymer matrices. Thiol-ene interfacial click reaction, as a metal-free click reaction, has been widely applied in the functionalization of surfaces and materials, showing superior advantages such as mild reaction conditions, high efficiency, and easy post-treatment.4 The surface modification via the thiol-ene interfacial click reaction has been reported on various materials, for examples, SBA-15 silica,5 stainless steel,6-8 glass and silicon,9,10 Keratin fibers,11 and so on. The UV-induced thiolene click reaction has also been used for functionalization of multi-walled carbon nanotube (CNT)12 and carbon fiber13 to improve the interfacial interactions. Furthermore, the UV-triggered thiol-ene interfacial click reaction has been developed for the surface modification of clays. Ammar et al designed montmorillonite/mercaptosuccinic acid material was employed as an adsorbent for the removal of Pb(II) from aqueous solutions, by radical thiol-ene coupling between methacrylate-silanized clay and mercaptosuccinic acid at 365 nm.14 And various clay nanocomposites have been prepared in the form of film or membrane via the interfacial thiol-ene polymerization with polymerizable organoclays.15,16 Shi et al fabricated the nanostructured thermoplastic elastomeric composite films based on poly(styrene-b-butadieneb-styrene) (SBS) crosslinked by polyhedral oligomeric silsesquioxane (POSS), via the UVinduced thiol-ene click crosslinking reaction between thiol functional groups from the POSS molecules and the double bonds within the soft block segment of SBS.17


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Compared with the UV-triggered thiol-ene interfacial click reaction, the thermal-triggered thiol-ene interfacial click reaction possessed unique features, such as high reaction degree,10 bulky product with uniform microstructure owing to the distinct advantage that the reaction is not affected by light transmittance. By now, there is no report on the clay/polymer nanocomposites or polymer-modified clays via the thermal-triggered thiol-ene interfacial click reaction. In the present work, the surface modification of attapulgite (ATP) nanorods with nitrile butadiene rubber (NBR) was investigated via thiol-ene interfacial click reaction for the first time, between the surface thiol groups on the modified attapulgite (ATP-SH) nanorods and the double bonds within the NBR rubber (Scheme 1). With different feeding ratios between the ATP-SH and NBR, the rubber grafted attapulgite nanorods or crosslinked gels were obtained. And the possible mechanism was proposed. HO HO HO HO

OH OH OH OH OH

N

SH HS

MPS

SH HS

x

SH

ATP

1,4-unit

y

z

1,2-unit

NBR

ATP-SH

Thiol-ene interfacial click reaction

H2C-S H2C CH S-CH2CH2CH

S-CH2CH2

+

+

CH

HCH2CH2C-S S-CH2CH2CH

S-CH2CH2CH

CH

CH

H2C

S-CH2CH2 H2C-S S-CH2CH2 CH

(I)

(II)

(III)

ATP-NBR

Scheme 1. Surface silylation of ATP nanorods and the thiol-ene interfacial click reaction between the ATP-SH nanorods and NBR1806.


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EXPERIMENTAL SECTION

Materials and reagents. Attapulgite nanorods (Jiangsu Goldstone Attapulgite R&D Center Co. Ltd., Xuyi, China) were dried at 120 °C for 24 h before the further use. NBR1806 powder with acrylonitrile content of 18.41%, Mw of 264 kDa and Mw/Mn of 4.52 and water < 0.5%, a emulsion polymerization product from Lanzhou Petrochemical Research Center, Petrochemical Research Institute, PetroChina Co. Ltd. was used directly without any pre-treatment. γmercaptopropyltrimethoxysilane (MPS, 97%) was purchased from J&K Scientific Co. Ltd., Beijing, China. Absolute ethanol, toluene and other reagents were analytical grade and used as received. Surface silylation of ATP nanorods. The ATP-SH nanorods were prepared via the surface silylation of ATP nanorods with MPS, as reported previously.18 Typically, 2.00 g ATP nanorods were dispersed into 40 mL absolute ethanol with ultrasonication for 2 h. Then 0.20 mL of MPS was added and the mixture was refluxed with stirring for 8 h. After the reaction, the product was separated by centrifugation (10000 rpm for 8 min), and washed with ethanol by ultrasonicating for 30 min. After the centrifugation-washing cycles were repeated three times, the product was dried at 40 °C for 24 h. Thiol-ene interfacial click reaction. The thermal-triggered thiol-ene interfacial click reaction was conducted between the C=C groups in NBR1806 with the –SH groups in the ATP-SH nanorods with different mass ratios (Table 1). NBR1806 was dissolved into 30 mL of toluene. The ATP-SH nanorods were dispersed into another 30 mL of toluene in N2 atmosphere. Then the two solutions were combined and degassed by three freeze-pump-thaw cycles under N2 atmosphere for three times. The final mixture was heated at 80 °C with stirring for 8 h. After cooling to the room temperature, the polymer-modified ATP (ATP-NBR) nanorods were


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separated by centrifugation (10000 rpm for 3 min), and washed with toluene by ultrasonicating for 30 min for three times, and finally dried at 40 °C for 24 h.

Table 1. Feeding mass ratios of the ATP-SH nanorods with NBR1806 in the thiol-ene interfacial click reaction.

a

Samples

ATP-SH (g)

NBR1806 (g)

Feeding ratio

PG (%)a

ATP-NBR-1

1.00

3.00

1:3

51.4

ATP-NBR-2

2.00

2.00

1:1

31.5

ATP-NBR-3

3.00

1.00

3:1

25.3

Percentage of grafting, defined as the mass ratio of the grafted polymer with the ATP nanorods

Characterization. Fourier Transform Infrared (FTIR) Spectrometer (NEXUS 670, Nicolet, Germany) was used to confirm the feature groups of samples in the range of 400-4000 cm-1, using KBr pellet method. X-ray photoelectron spectroscopy (XPS) analysis was performed using a VG Scientific ESCALAB 250Xi-XPS photoelectron spectrometer with an Al Kα X-ray resource. The binding energies were calibrated by the C1s binding energy of 284.7 eV. The morphological analysis of the products was carried out on a JEM-1200 EX transmission electron microscope (TEM). The samples were dispersed in toluene with concentration of 5.0 mg/mL. The dispersion was dip-coated onto the carbon-coated copper grid, and dried at room temperature before observation. Dynamical light scattering (DLS) measurements were performed on the Light Scattering System BI-200SM, Brookhaven Instruments device equipped with the BI-200SM goniometer and


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the Coherent INOVA 70C argon-ion laser at 20 °C, using 135 mW intense laser excitation at 514.5 nm and at a detection angle of 90° using the PDOX-NPs dispersion directly at 25 °C. Thermogravimetric (TG) analysis was performed with a Perkin-Elmer TGA-7 system at a scan rate of 10 °C/min to 800 °C in N2 atmosphere.

RESULTS AND DISCUSSION

Surface

silylation.

In

the

surface

silylation

of

ATP

nanorods

with

γ-

mercaptopropyltrimethoxysilane (MPS), the ATP nanorods were modified with a low amount of MPS, in order to avoid the welding effect as far as possible,18 which would resulted to the covalent aggregation and decrease subsequently the dispersibility of the functionalized ATP nanorods. The strong characteristic absorbance around 480 and 1000 cm−1 in the FT-IR spectrum of the pristine ATP nanorods were attributed to the bending vibration of Si-O-Si bond in the ATP framework. Those in 3700–3200 cm−1 were associated with the stretching vibration of the structural OH groups, while the absorbance band at 1656 cm−1 was belonged to the OH bending frequency. The absorbance at 1446 cm-1 was attributed to the C-O stretching modes of the carbonate ion. After the surface silylation, the weak C-H stretching vibrations below 3000 cm-1 and the in-plane bending vibration at 1370 cm-1 appeared (Figure 1), indicating the successful silylation of ATP nanorods. Furthermore, no absorbance around 550 cm-1 could be seen, demonstrating that no disulfides (S-S bridge) formed during the surface silylation.19 XPS technique was also used to reveal the surface modification of ATP nanorods with MPTMS (Figure 2). After the surface modification, the surface atomic concentrations of the main elements (O, Fe, Mg and Al) in ATP mineral decreased, except Si (Table 2). And S element,


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which could not be detected in the pristine ATP nanorods, appeared in the product after the surface modification, with a surface atomic concentration of 1.43%. Such results demonstrated the successful surface modification of the ATP nanorods with MPTMS.

Table 2. Surface atomic concentrations of the pristine ATP, ATP-SH and ATP-NBR sample. Samples

Surface atomic concentrations (%) O

ATP

Si

Fe

Mg

Al

43.58 18.42 11.25 9.29 7.78

ATP-SH

C

N

S

6.27

3.41

0

40.33 25.54

6.29

3.50 6.41 14.13 2.37 1.43

ATP-NBR-1 32.03 16.72

1.51

1.63 2.64 41.55 3.05 0.87

80 70

Transmittance (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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ATP

60 ATP-SH

50 40 30 20

ATP-NBR-1

10 0 4000 3500 3000 2500 2000 1500 1000

500

Wavenumber (cm-1)

Figure 1. FT-IR spectra of the ATP, ATP-SH, and ATP-NBR-1 sample.


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140000 O 1s

ATP ATP-SH ATP-NBR-1

120000 100000

Intensity (a.u.)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


C 1s

80000 60000

Mg 1s

S 2p Si 2p Si 2s

40000 20000

Fe 2p3/2 N 1s

Al 2p

0 0

200

400

600

800

1000 1200

Binding Energy (ev)

Figure 2. XPS survey spectra of the pristine ATP, ATP-SH, and ATP-NBR-1 sample.

In the TGA analysis, the pristine ATP and ATP-SH nanorods showed two and three main steps of mass loss: i) < 200 °C due to the surface adsorbed water/or ethanol; ii) 250-500 °C assigned to the removal of zeolitic water from the channels, hydrogen-bonded to Al-OH or Si-O-Si groups in the fibrous structure and the decomposition of grafted alkoxides and the decomposition of the alkyl chain; iii) 500-700 °C assigned to the decomposition of organic moiety and dehydroxylation of ATP nanorods (Figure 3).20 The ratio between the total mass loss in the last two stages and the mass of the residual at 700 °C was used to estimate the silylation degree. Here, the silylation degree was calculated to be 9.86% for the ATP-SH nanorods. It meant a thiol content of 1.31 mmol/g in the ATP-SH nanorods.


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100 95 90

Mass (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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85 ATP-SH ATP-NBR-1 ATP-NBR-2 ATP-NBR-3 ATP

80 75 70 65 60 100

200

300

400

500

600

700

800

Temperature ( C) o

Figure 3. TGA curves of the pristine ATP, ATP-SH and ATP-NBR samples.

The dispersibility of the ATP-SH nanorods in toluene was investigated by the TEM technique (Figure 4). The ATP-SH nanorods showed the separated nanorods without obvious aggregation, similar as the bare ATP nanorods dispersed in water. The result demonstrated that the welding effect and locking effect had been efficiently inhibited in the surface silylation with less silane.

ATP

ATP-SH


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ATP-NBR-1

ATP-NBR-2

ATP-NBR-3

Figure 4. TEM images of the bare ATP nanorods (in aqueous dispersion), ATP-SH nanorods, and the ATP-NBR samples.

Thiol-ene interfacial click reaction. Then the surface modification of attapulgite (ATP) nanorods with nitrile butadiene rubber (NBR) was investigated for the first time, via thiol-ene interfacial click reaction between the surface thiol groups on the modified attapulgite (ATP-SH) nanorods and the double bonds within the NBR rubber (Scheme 1). After the thiol-ene interfacial click reaction, the solid product, ATP-NBR, was separated and collected by centrifugation, washed with toluene to ensure the complete removal of the free NBR molecules. With different feeding ratios between the ATP-SH and NBR (Table 1), the characteristic absorbance of -CN group at 2238 cm-1 arose in the FT-IR spectra of the product,21 and the C-H stretching vibrations at 2926 and 2853 cm-1 had been distinctly enhanced (Figure 1). It indicated that the NBR


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molecules had been successfully modified onto the surface of the ATP nanorods. In the XPS survey, the surface atomic concentrations of the elements, which were detected in the ATP-SH nanorods such as O, Si, Fe, Mg, Al, and S decreased while those of C and N elements increased after the thermal-triggered thiol-ene interfacial click reaction (Table 2), also indicated the successful graft of NBR onto the ATP nanorods. The three ATP-NBR samples showed a main weight loss in the temperature range of 250-700 °C (Figure 3), attributed to the thermal decomposition of the grafted polymers. The percentage of grafting (PG%, defined as the mass ratio of the grafted polymer with the ATP nanorods) was calculated from the TGA analysis results, as 51.4%, 31.5% and 25.3% for the ATP-NBR-1, ATP-NBR-2 and ATP-NBR-3 samples, which were prepared with the feeding ratios between the ATP-SH and NBR of 1:3, 1:1, or 3:1, respectively. These PG% values were higher than those in the common “grafting onto” approach. Clearly, the feeding ratios between the ATP-SH and NBR played an important role in the resultant PG% value, namely, the surface thiol groups on the ATP-SH nanorods and the double bonds within the NBR rubber. In fact, the C=C bonds in the 1,4- butadiene units could hardly participate in the thiol-ene reaction, especially they are trans-structure in NBR, due to their bigger space hindrance than these in the 1,2-butadiene units.17 So the thiol-ene reaction should take place between the –SH groups in the ATP-SH nanorods and the 1,2-C=C groups in NBR1806 (Scheme 1). Considering the acrylonitrile content of 18.41% and 1,2-C=C group of 7.1% in the butadiene units, the 1,2-C=C group content is 1.07 mmol/g in the NBR1806 sample. The dispersibility and dispersion stability of the three ATP-NBR samples were evaluated in toluene with a concentration of 2.5 mg/mL after ultrasonication for 10 min. The ATP-NBR-1 sample, which was prepared with excess 1,2-C=C groups in NBR1806, could not be dispersed at all (Figure 5a). The ATP-NBR-2 and ATP-NBR-3 samples, prepared with nearly equivalent 1,2-


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C=C groups in NBR1806 and excess -SH groups in the ATP-SH nanorods respectively, could be partially dispersed with little sedimentation, but almost deposited completely within 2 min (Figure 5b). Such difference should be resulted from the different agglomerates sizes of the ATPNBR samples prepared with the different feeding ratios. The sediment volume of the latter one was less than the former one, meaning that the agglomerates in the latter one were smaller than the former one. The result demonstrated that the small agglomerates could be obtained with excess -SH groups in the ATP-SH nanorods, meaning a possible application to prepare the NBR grafted ATP nanorods, but not agglomerates with crosslinked network.

(a) 0 min

(b) 2 min

(c) 30 min

(d) 150 min

Figure 5. Digital photos of the dispersion of the ATP-NBR samples prepared with different feeding ratios after standing for 0 min (a), 2 min (b), 30 min (c) and 150 min (d).


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100

(b)

100

(a)

80

80

60

60

Intensity

Intensity

40 20

40 20

0

0

0

2000

4000

6000

8000

10000

0

2000

Diameter (nm)

4000

6000

8000

10000

Diameter (nm)

(c)

100 80

Intensity

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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60 40 20 0 0

2000

4000

6000

8000

10000

Diameter (nm)

Figure 6. Typical hydrodynamic diameter distribution of the ATP-NBR-2 (a), ATP-NBR-3 (b) and ATP-NBR-4 (c).

To reveal the potential, the thiol-ene interfacial click reaction was also carried out with the feeding ratios between the ATP-SH and NBR of 10:1. The product, ATP-NBR-4, could be dispersed well in toluene, and it could not deposited completely within 150 min (Figure 5d). To further establish the particle size of the products and avoid the effect of the aggregation during the sampling procedure, DLS technique was used to measure their hydrodynamic diameter of the dispersible parts. For the ATP-NBR-1 prepared with the feeding ratios between the ATP-SH and NBR of 1:3, which could not be dispersed in toluene (Figure 5), no data was obtained with


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diameter less than 10 µm. The ATP-NBR-2, prepared with the feeding ratios between the ATPSH and NBR of 1:1, showed the smaller diameter of about 10 µm, while the ATP-NBR-3, prepared with the feeding ratios between the ATP-SH and NBR of 3:1, showed the smaller diameter of the agglomerates near 6 µm (Figure 6 a and b). As for the ATP-NBR-4, which was prepared with the feeding ratios between the ATP-SH and NBR of 10:1, a diameter range of 1.53 µm was achieved (Figure 6 c). The value is near to the length of the single pristine ATP nanorods, indicating the NBR grafted ATP nanorods could be obtained with large excess of ATP-SH, with little agglomerates with crosslinked network. TEM technique was used to clarify the microstructure of the ATP-NBR samples, as shown in Figure 4. Although the rubber layer could not be observed in the surface of the single ATP nanorods in the TEM analysis due to the low PG%, it could be clearly seen in the agglomerates of ATP nanorods (the regions with lighter contrast between the ATP nanorods with deeper contrast). It was direct evidence for the successful grafting. The ATP-NBR-1 sample showed bulky aggregates up to 10 µm, without single nanorods. Additionally, the edge of the aggregates was unclear and the ATP nanorods were difficult to identify within the aggregates. It demonstrated the gelation reaction occurred in the thiol-ene reaction with excess 1,2-C=C groups in NBR1806, in which the ATP-SH nanorods with more than one -SH group acted as the crosslinker.22 The ATP-NBR-2 sample, prepared with nearly equivalent 1,2-C=C groups in NBR1806, showed micro-scaled gels, in which the ATP nanorods could be distinctly identified due to the lower PG%. Further increasing the feeding ratio of the ATP-SH nanorods, as for the ATP-NBR-3 sample, both aggregates and single ATP nanorods could be seen. Based on the fact that the ATP-


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NBR-3 sample could dispersed well in toluene (Figure 5), it could be deduced that the aggregates should be non-covalent, which were produced during the drying process. According to the morphology and size of the products, the formation mechanism could be proposed as following: i) while in the thiol-ene reaction with excess –SH groups in the ATP-SH nanorods, they tended to react with the 1,2-C=C groups from the same NBR molecule, thus the NBR grafted ATP nanorods (I in Scheme 1) were produced; ii) in the reaction with excess 1,2C=C groups in NBR1806, the –SH groups in the ATP-SH nanorods were inclined to react with the 1,2-C=C groups from different NBR molecules, thus the gels (III in Scheme 1) were formed; iii) while as in the reaction with nearly equivalent 1,2-C=C groups in NBR1806 and –SH in the ATP-SH nanorods, the microgels (II in Scheme 1) were resulted by the both reactions abovementioned. Inevitably, some looser microgels, which could be swollen drastically, would be also produced with the longer ATP nanorods,23 especially with the low surface silylation degree in the present. Based on the above results and discussion, the crosslinked ATP-NBR nanocomposites could be produced via the thiol-ene interfacial click reaction with excess NBR, while the NBR grafted ATP nanorods could be synthesized via the reaction with excess ATP-SH nanorods. Such results showed promising potential in rubber industry. For example, the crosslinked ATP-NBR network could be formed in the vulcanized rubber-based nanocomposites to enhance their mechanical strength, by adding ATP-SH nanorods into the vulcanization system with a lower feeding ratio. As a result, the ATP-NBR nanocomposites could be obtained as a double crosslinked interpenetrating network. As for the preparation of NBR grafted ATP nanorods as both toughing agent and reinforcing agent for plastics, the ATP-SH nanorods are feed with a higher feeding ratio. The resultant NBR grafted ATP nanorods showed unique advantages, such as efficient


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surface modification, good dispersibility with less crosslinked network, in the form of ATP-NBR nanorods.

CONCLUSIONS

In summary, the surface modification of attapulgite (ATP) nanorods with nitrile butadiene rubber (NBR) was investigated via thiol-ene interfacial click reaction for the first time, between the surface thiol groups on the modified attapulgite (ATP-SH) nanorods and the double bonds within the NBR rubber. The rubber grafted attapulgite nanorods or crosslinked gels were obtained with different feeding ratios between the ATP-SH and NBR. A possible mechanism was proposed based on the TGA, morphological analysis and dispersibility investigation, as following: the –SH groups in the ATP-SH nanorods tended to react with the 1,2-C=C groups from the same NBR molecule when the ATP-SH were excess, resulting to NBR grafted ATP nanorods; while they were inclined to react with the 1,2-C=C groups from different NBR molecules with excess NBR, producing crosslinked gels. Such characteristics demonstrated the thiol-ene interfacial click reaction a versatile approach for the preparation of the crosslinked ATP-rubber nanocomposites or rubber grafted ATP nanorods, by facile adjusting the feeding ratio between the butadienebased rubbers and the ATP-SH nanorods.

AUTHOR INFORMATION Corresponding Author * Corresponding Author. Tel./Fax: 86 0931 8912582. Email: [email protected]. Notes


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Page 18 of 22

The authors declare no competing financial interest.

ACKNOWLEDGMENTS This work was supported by the Open Project of the Key Laboratory of Clay Mineral Applied Research of Gansu Province (CMAR-03).

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TOC

HO HO HO HO

OH OH OH OH OH

N

SH HS

MPS

SH HS

x

SH

1,4-unit

z

NBR

ATP-SH

ATP

y

1,2-unit

Thiol-ene interfacial click reaction

H2C-S H2C CH S-CH2CH2CH

S-CH2CH2

+

+

CH

HCH2CH2C-S S-CH2CH2CH

S-CH2CH2CH

CH

CH

H2C

S-CH2CH2 H2C-S S-CH2CH2 CH

(I)

(II)

(III)

ATP-NBR


22

Surface Modification of Attapulgite Nanorods with Nitrile Butadiene

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