Preparation of Lignin/silica Nanoparticle Based Microcapsules and Their Application in Self-healing Coatings†

doi:10.7503/cjcu20190045

Abstract

Abstract:

Phosphorylated lignin/silica nano composites(PAL/SiO₂) were used as shell material to encapsulate active isophorone diisocyanate(IPDI) to prepare microcapsules(PAL/SiO₂-IPDI). A small amount of polymeric methane diisocyanate(PMDI) with more reactivity was added to react with residual water to form polyurea, which could effectively increase the wall thickness of the microcapsules and improve the stability of the system. The effects of PAL/SiO₂ nano composite content, water-oil ratio and shearing rate on the morphology, particle size and wall thickness of microcapsules were studied by optical microscopy(OM), scanning electron microscopy(SEM) and dynamic light scattering(DLS). The results show that the prepared PAL/SiO₂-IPDI microcapsules were spherical with a wall thickness of 2.36—3.50 μm and an average diameter of 40.3—201.5 μm under optimum preparation conditions. Fourier transformed infrared spectroscopy(FTIR) and thermogravimetric analysis(TGA) revealed that the healing agent IPDI was successfully embedded as a core material in the microcapsules with a content of approximately 82.8%. The PAL/SiO₂-IPDI microcapsules were blended with epoxy resin to prepare self-healing coatings. The anti-corrosion tests in the high salt concentration solution show that the epoxy resin coating containing 4%(mass fraction) PAL/SiO₂-IPDI microcapsules could heal quickly after scratching, which significantly reduced the corrosion current and corrosion rate of the iron substrate. SEM images demonstrate that the pure epoxy coating had no sign of healing at the scratching area, while that in the self-healing epoxy coating was filled with cross-linking polymer. In addition, the nano indentation tests show that the hardness value of the epoxy coating increased from 249.99 MPa to 302.98 MPa after adding PAL/SiO₂-IPDI microcapsules, and the elastic modulus was also improved.

Key words: Lignin, Silica, Composite nanoparticles, Microcapsule, Self-healing coating

CLC Number:

O636
O646.21

TrendMD:

LI Lan,QIAN Yong,YANG Dongjie,QIU Xueqing. Preparation of Lignin/silica Nanoparticle Based Microcapsules and Their Application in Self-healing Coatings^†[J]. Chem. J. Chinese Universities, 2019, 40(6): 1293.

Figures/Tables 11

Scheme 1 Preparation of microcapsule process schematic diagram

Table 1 Parameters of PAL/SiO2 emulsion with different water/oil ratios and PAL/SiO2 contents

Sample	Water phase		Oil phase		O/W volume ratio	Mean diameter/μm
Sample	V(Water)/mL	Mass fraction of PAL/SiO₂(%)	V(IPDI)/mL	V(PMDI)/mL	O/W volume ratio	Mean diameter/μm
a	12	0.5	3	1	1∶3	40.3
b	12	0.5	5	1	1∶2	49.3
c	6	0.5	3	1	1∶1.5	56.6
d	5	0.5	4	1	1∶1	49.5
e	3	0.5	5	1	0.5∶1	152.4
f	5	0.1	4	1	1∶1	201.5
g	5	1.0	4	1	1∶1	46.7
h	5	2.0	4	1	1∶1	43.6

Fig.1 Optical images of PAL/SiO2 emulsion with different water/oil ratios and PAL/SiO2 content —(H) are samples a—h of Table 1.

Table 2 Parameters of PAL/SiO2 emulsion with different speeds

Speed/ (r·min^-1)	Water phase		Oil phase		O/W volume ratio	Mean diameter/μm
Speed/ (r·min^-1)	V(Water)/mL	Mass fraction of PAL/SiO₂(%)	V(IPDI)/mL	V(PMDI)/mL	O/W volume ratio	Mean diameter/μm
11000	6	0.5	3	1	1∶1.5	73.1
13000	6	0.5	3	1	1∶1.5	56.7
16000	6	0.5	3	1	1∶1.5	56.4
19000	6	0.5	3	1	1∶1.5	55.4
22000	6	0.5	3	1	1∶1.5	43.7

Fig.2 Size distribution and optical microscope(inset)(A) and SEM images of PAL/SiO2 micocapsules(B, C) and the shell(D)

Fig.3 FTIR spectra(A) and TGA curves(B) of PAL/SiO2 shell(a), IPDI(b) and the IPDI-loaded microcapsules(c)

Fig.4 Corrosion performance of steel panels coated with pure(A1, A2) and self-healing(B1, B2) epoxy coatings before(A1, B1) and after(A2, B2) in 10% NaCl solution for 24 h

Fig.5 SEM images of pure(A)and self-healing epoxy(B) coating and its anti-corrosion performance fter being scratched

Fig.6 Tafel plots of pure and self-healing epoxy coatings containing 4% PAL/SiO2 microcapsules coated on steels

Table 3 Tafel parameters of pure and self-healing epoxy coatings containing 4% PAL/SiO2 microcapsules coated on steels

Sample	Current, I/A	Corrosion rate/(mm·a^-1)
Steel	2.29×10^-5	3.35×10^-1
Epoxy	3.69×10^-7	5.39×10^-3
Self-healing epoxy	5.27×10^-8	7.70×10^-4
Epoxy after rupture	3.63×10^-5	5.31×10^-1
Self-healing epoxy after rupture	6.48×10^-6	0.95×10^-3

Fig.7 Nanoindentation load-displacement curves of different PAL/SiO2 content coatings

References 32

[1]	Samadzadeha M., Hatami B. S., Peikaria M., Kasirihab S. M., Ashrafic A., Progress in Organic Coatings,2010, 68, 159-164
[2]	Cho S. H., White S. R., Braun P. V., Advanced Materials,2009, 21, 645-649
[3]	Sun D. W., Zhang H., Tang X. Z., Yang J. L., Polymer,2016, 91, 33-40
[4]	Song Y. K., Jo Y. H., Lim Y. J., Cho S. Y., Yu H. C., ACS Applied Materials and Interfaces,2013, 5, 1378-1384
[5]	Zhu Y. X., Yin T., Ren J. Y., Liu C. H., Fu D. G., Ge L. Q., RSC Advances,2016, 6, 12100-12106
[6]	Ana S., Lee M. W., Yarin A. L., Yoon S. S., Chemical Engineering Journal,2018, 344, 206-2201
[7]	White S. R., Sottos N. R., Geubelle P. H., Moore J. S., Nature,2001, 409, 7427-7433
[8]	Suryanarayana C. V., Rao K. C., Kumar D., Progress in Organic Coatings,2008, 63, 72-78
[9]	Boura S. H., Peikari M., Ashrafi A., Samadzadeh M., Progress in Organic Coatings,2012, 75, 292-300
[10]	Brown E. N., Kessler M. R., Sottos N. R., White S. R., Journal of Microencapsulation,2003, 20, 719-730
[11]	Fix D., Andreeva D. V., Lvov Y. M., Shchukin D. G., Möhwald H., Advanced Functional Materials,2009, 19, 1720-1727
[12]	Yang J. L., Keller M. W., Moore J. S., White S. R., Sottos N. R., Macromolecules,2008, 41, 9650-9655
[13]	Huang M. X., Yang J. L., Journal of Materials Chemistry,2011, 21, 11123-11130
[14]	Nguyen L. T. T., Hillewaere X. K. D., Teixeira R. F. A., Berga O. V. D., Prez F. D., Polymer Chemistry,2015, 6, 1159-1170
[15]	Sun D. W., An J. L., Wu G., Yang J. L., Journal of Materials Chemistry A,2015, 3, 4435-4444
[16]	Liu W. J., Jiang H., Yu H. Q., Green Chemistry,2015, 17(11), 4888-4907
[17]	Zhang J. F., Chen Y., Sewella P., Brook M. A., Green Chemistry,2015, 7, 1811-1819
[18]	Tuomela M., Vikman M., Hatakka A., Itavaara M., Bioresource Technology,2000, 72(2), 169-183
[19]	Stewart D., Industrial Crops and Products, 2008, 27(2), 202-207
[20]	Guo Y. R., Yu F. D., Fang G. Z., Journal of Alloys and Compounds,2013, 552, 70-75
[21]	Tiarks F., Landfester K., Antonietti M., Langmuir,2001, 17(19), 5775-5780
[22]	Li C. Q., Yang D. J., Xi Y. B., Qin Y. L., Qiu X. Q., Chem. J. Chinese Universities,2018, 39(12), 2725-2733
	(李常青,杨东杰,席跃宾,秦延林,邱学青.高等学校化学学报, 2018, 39(12), 2725-2733)
[23]	Hayashi J., Shoji T., Watada Y., Muroyama K., Langmuir,1997, 13(15), 4185-4186
[24]	KlapiszewskiŁ.,Madrawska M., Jesionowski T., Physicochemical Problems of Mineral Processing,2012, 48(2), 463-473
[25]	Nowacka M., Klapiszewski Ł., Norman M., Jesionowski T., Central European Journal of Chemistry,2013, 11(11), 1860-1873
[26]	KlapiszewskiŁ., Królak M., Jesionowski T., Central European Journal of Chemistry,2014, 12(2), 173-184
[27]	Xiong W. L., Yang D. J., Zhong R. S., Li Y., Zhou H. F., Qiu X. Q., Industrial Crops and Products,2015, 74, 285-292
[28]	Xiong W. L., Qiu X. Q., Yang D. J., Zhong R. S., Qian Y., Li Y. Y., Wang H., Chemical Engineering Journal,2017, 326, 803-810
[29]	Wu G., An J. L., Sun D. W., Tang X. Z., Xiang Y., Yang J. L., J. Mater. Chem. A,2014, 2, 11614-11620
[30]	Kirk J. G., Naik S. J., Moosbrugger J. C., Morrison D. J., Volkov D., Sokolov I., International Journal of Fracture,2009, 159(1), 101-102
[31]	Wei H. G., Wang Y. R., Guo J., Shen N. Z., Jiang D. W., Zhang X., Yan X. R., Zhu J. H., Wang Q., Shao L., Lin H. F., Wei S. Y., Guo Z. H., J. Mater. Chem. A,2015, 3(2), 469-480
[32]	Yi H., Yang Y., Gu X. Y., Huang J., Wang C. Y., J. Mater. Chem. A,2015, 3(26), 13749-13757