Molecular Dynamics Investigation of Adhesion Between CL-20/TNT Co-crystal Surfaces and Adhesives of PLA, PCL, P(LA-co-CL)†

doi:10.7503/cjcu20180331

Abstract

Abstract:

Molecular dynamics simulations were performed to study the adhesion properties of green adhesives onto four different co-crystal surfaces of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexazisowurtziane/2,4,6-trinitrotoluene(CL-20/TNT). The green adhesives studied in this article include polyactic acid(PLA), polycaprolactone(PCL) and their copolymer[P(LA-co-CL)]. Simulations of the bulk polymers were employed over a wide range of temperatures including the volumetric glass transition temperature, so as to validate the force field used. The computed glass transition temperatures and densities compare well with experiment and calculation based on group additive method. Simulations of the interfaces show that the wettability are obviously greater for the crystal surfaces and adhesive molecules both having much polarity. The pair correlation function computations illustrate that in this case, there are apparently a number of H-O atom pairs in 0.5 nm ranges among these interfaces. The wettability for PCL with lowest polarity among the three adhesive molecules on all crystal surfaces studied here are all significantly smaller.

Key words: 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexazisowurtziane/2,4,6-trinitrotoluene(CL-20/TNT) co-crystal, Green adhesive, Adhesion property, Molecular dynamics(MD) simulation, Polyactic acid, Polycaprolactone

CLC Number:

TrendMD:

LIU Bei, GAO Pei, LI Shenshen, XIAO Yunqin, XIAO Jijun. Molecular Dynamics Investigation of Adhesion Between CL-20/TNT Co-crystal Surfaces and Adhesives of PLA, PCL, P(LA-co-CL)^†[J]. Chem. J. Chinese Universities, 2018, 39(11): 2556.

Figures/Tables 11

Fig.1 Primitive cell of CL-20/TNT co-crystal(A) and primary cell of CL-20/TNT co-crystal(B)CL-20 in line mode and TNT in ball-stick mode.

Fig.2 Four side views of different surface models of CL-20/TNT co-crystalCL-20 in line mode and TNT in ball-stick mode. (A)(001); (B)(100); (C)(010)H; (D)(010)T.

Fig.3 Initial (001) CL20/TNT co-crystal/PLA interface used in the MD simulation(co-crystal in CPK and PLA in ball-stick)

Fig.4 Specific volume vs. temperature for PLA(A), PCL(B) and P(LA-co-CL)(C) at 105 Pa as determined from MD simulations

Table 1 Densities and glass transition temperatures of the polymers

Polymer	Density/(g·cm^-3)(298 K)			T_g/℃
Polymer	Experiment	This work	Synthia^[27]	Experiment	This work
PLA	1.24^[28]	1.17±0.01	1.25	55—60^[30]	59
PCL	1.15^[29]	1.11±0.01	1.10	-60^[31]	-57
P(LA-co-CL)		1.12±0.01	1.16	-15^[31]	-15

Table 2 Surface tension(γ), interfacial tension(γ12), work of adhesion(W12) and spreading coefficient(S) for the polymers(γ2) interfaced to the CL-20/TNT co-crystal(γ1)(10-3 J/m2)

Crystal surface	Polymer	γ₁	γ₂	γ₁₂	W₁₂	S
(001)	PLA	131	28±4	-477±1	636	580
	PCL	131	49±2	-56±4	236	138
	P(LA-co-CL)	131	42±1	-486±3	659	575
(100)	PLA	144	28±4	-28±3	200	144
	PCL	144	49±2	-8±5	201	103
	P(LA-co-CL)	144	42±1	12±4	174	90
(010)T	PLA	140	28±4	-65±4	233	177
	PCL	140	49±2	-40±2	229	131
	P(LA-co-CL)	140	42±1	-53±4	235	151
(010)H	PLA	140	28±4	-252±3	420	364
	PCL	140	49±2	-49±3	238	140
	P(LA-co-CL)	140	42±1	-354±2	536	452

Fig.5 Comparison of the work of adhesion(W12)(A) and the spreading coefficient(S)(B) for PLA, PCL and P(LA-co-CL) interfaced to the different CL-20/TNT co-crystal surfaces

Fig.6 Carbon density profiles for PLA at (001)(A), (010)H(B), (010)T(C) and (100)(D) surfaces of CL-20/TNT co-crystal

Fig.7 Snapshots of the time evolution of a single PLA polymer chain at (001)(A), (010)H(B), (010)T(C) and (100)(D) surfaces of CL-20/TNT co-crystal interface at 0.2 intervalsFrom left to right: the chronological order is 0, 0.2, 0.4 ns.

Fig.8 PCFs for atom pairs of H and O atoms in PLA with O[H(P)—O, a] and H[O(P)—H, b] atoms in CL-20/TNT co-crystal at(001) surface at 380 K, respectively(A) g(r) converged to 1; (B) close-up g(r) of the region of interest.

Table 3 Integral areas of PCF curves for different atom pairs in the interfaces between polymers and co-crystal surfaces

Crystal surface	Polymer	Distance/nm	H(P)—O	O(P)—H
(001)	PLA	0.20—0.31	1.87	3.04
	PCL		1.37	2.45
	P(LA-co-CL)		1.89	3.31
	PLA	0.31—0.50	5.57	5.84
	PCL		5.03	4.97
	P(LA-co-CL)		5.68	5.92
(010)H	PLA	0.20—0.31	2.14	0.75
	PCL		1.57	0.59
	P(LA-co-CL)		2.33	0.78
	PLA	0.31—0.50	6.18	4.59
	PCL		5.73	4.27
	P(LA-co-CL)		6.45	5.03
(010)T	PLA	0.20—0.31	1.73	0.68
	PCL		1.69	0.57
	P(LA-co-CL)		1.78	0.72
	PLA	0.31—0.50	4.45	3.46
	PCL		4.33	3.27
	P(LA-co-CL)		4.48	3.57
(100)	PLA	0.20—0.31	1.02	0.33
	PCL		1.03	0.29
	P(LA-co-CL)		1.07	0.32
	PLA	0.31—0.50	2.82	3.22
	PCL		2.78	3.19
	P(LA-co-CL)		2.87	3.04

References 38

[1]	Yan Q. L., Zeman S., Elbeih A., Thermochimica Acta, 2012, 537, 1—12
[2]	Xiao J. J., Zhu W. H., Zhu W., Xiao H. M., Molecular Dynamics of Energetic Materials, Science Press, Beijing, 2013
	(肖继军, 朱卫华, 朱伟, 肖鹤鸣. 高能材料分子动力学, 北京: 科学出版社, 2013)
[3]	Bolton O., Matzger A. J., Angewandte Chemie International Edition, 2011, 50(38), 8960—8963
[4]	Yang Z. W., Huang H., Li H. Z., Zhou X. Q., Li J. S., Nie F. D., Chinese Journal of Energetic Materials, 2012, 20(2), 256—257
	(杨宗伟, 黄辉, 李洪珍, 周小清, 李金山, 聂福德. 含能材料, 2012, 20(2), 256—257)
[5]	Wang J. Y., Li H. Q., An C. W., Guo W. J., Chinese Journal of Energetic Materials, 2015, 23(11), 1103—1106
	(王晶禹, 李鹤群, 安崇伟, 郭文建. 含能材料, 2015, 23(11), 1103—1106)
[6]	Chen P. Y., Zhang L., Zhu S. G., Cheng G. B., Chinese Journal of Structural Chemistry, 2016, 35(2), 246—256
[7]	Guo D., An Q., Iii W. A. G., Zybin S. V., Huang F., Journal of Physical Chemistry, C, 2016, 118(51), 30202—30208
[8]	Liu Q., Xiao J. J., Zhang J., Zhao F., He Z. H., Xiao H. M., Chem. J. Chinese Universities, 2016, 37(3), 559—566
	(刘强, 肖继军, 张将, 赵峰, 何正华, 肖鹤鸣. 高等学校化学学报, 2016, 37(3), 559—566)
[9]	Lai S. M., Hsieh Y. T., Journal of Macromolecular Science, Part B, 2016, 55(3), 211—228
[10]	Aldana D. S., Villa E. D., Hernandez M. D. D., Sanchez G. G., Cruz Q. R., Gallardo S. F., Castillo H. P., Casarrubias L. B., Polymers, 2014, 6(9), 2386—2403
[11]	Iwata T., Angewandte Chemie International Edition, 2015, 54(11), 3210—3215
[12]	Wu G. H., Liu S. Q., Jia H. S., Dai J. M., Journal of Wuhan University of Technology: Materials Science Edition, 2016, 31(1), 164—171
[13]	Way C., Dean K., Wu D. Y., Palombo E., Polymer Degradation & Stability, 2012, 97(3), 430—438
[14]	Hwang S. W., Shim J. K., Selke S., Soto-Valdez H., Rubino M., Auras R., Macromolecular Materials & Engineering, 2013, 298(6), 624—633
[15]	Ren H., Zhang Q., Chen X., Zhao W., Zhang J., Zhang H. P., Zeng R., Xu S., Polymer, 2007, 48(3), 887—893
[16]	Bolton O., Matzger A. J., Angewandte Chemie International Edition, 2011, 50(38), 8960—8963
[17]	Sun T., Xiao J. J., Liu Q., Zhao F., Xiao H. M, Journal of Materials Chemistry, A, 2014, 2(34), 13898—13904
[18]	Sun T., Xiao J. J., Ji G. F., Zhao F., Xiao H. M., 2016, 13(3), 677—693
[19]	Bunte S. W., Sun H, The Journal of Physical Chemistry, B, 2000, 104(11), 2477—2489
[20]	Andersen H. C., Journal of Chemical Physics, 1980, 72(4), 2384—2393
[21]	Berendsen H. J. C., Postma J. P. M., Gunsteren W. F. V., DiNola A. R. H. J., Haak J. R., Journal of Chemical Physics, 1984, 81(8), 3684—3690
[22]	Allen M. P., Tildesley D. J., Computer Simulation of Liquids, Oxford University Press, New York, 1989
[23]	Ewald P. P., Ann Phys(Leipzig), 1921, 64, 253—287
[24]	Han J., Gee R. H., Boyd R. H., Macromolecules, 1994, 27(26),7781—7784
[25]	Zhang J., Liang Y., Yan J. Z., Lou J. Z., Polymer, 2007, 48(16), 4900—4905
[26]	Fu Y. Z., Hu S. Q., Lan Y. H., Liu Y. Q., Acta Chimica Sinica, 2010, 68(8), 809—813
	(付一政, 胡双启, 兰艳花, 刘亚青. 化学学报, 2010, 68(8), 809—813)
[27]	Bicerano J., Prediction of Polymer Properties, Chemical Rubber Company Press, Boca Raton, 2002
[28]	Nampoothiri K. M., Nair N. R., John R. P., Bioresource Technology, 2010, 101(22), 8493—8501
[29]	Wiria F. E., Leong K. F., Chua C. K., Liu Y., Acta Biomaterialia, 2007, 3(1), 1—12
[30]	Tsuji H., Sumida K., Journal of Applied Polymer Science, 2015, 79(9), 1582—1589
[31]	Grijpma D. W., Zondervan G. J., Pennings A. J., Polymer Bulletin, 1991, 25(3), 327—333
[32]	Shen Z., Zhao Z. G., Kang W. L., Colloid and Surface Chemistry, Chemistry Industry Press, Beijing, 2002
	(沈钟, 赵振国, 康万利. 胶体与表面化学, 北京: 化学工业出版社, 2012)
[33]	Gee R. H., Maiti A., Bastea S., Fried L. E., Macromolecules, 2007, 40(9), 3422—3428
[34]	Kirkwood J. G., Buff F. P., Journal of Chemical Physics, 1949, 17(3), 338—343
[35]	Zhang Y. H., Feller S. E., Brooks B. R., Pastor R. W., Journal of Chemical Physics, 1995, 103(23), 10252—10266
[36]	Jha K. C., Zhu H., Dhinojwala A., Tsige M., Langmuir, 2014, 30(43),12775—12785
[37]	Bekele S., Tsige M., Langmuir the ACS Journal of Surfaces & Colloids, 2013, 29(43),13230—13237
[38]	Krzeminski C., Brulin Q., Cuny V., Lecat E., Lampin E., Cleri F., Journal of Applied Physics, 2007, 101(12),6336—6339