DFT study on effects of hydrolysis degrees of 3-mercaptopropyltriethoxysilane on grafting mechanisms of nano-silica

doi:10.11949/j.issn.0438-1157.20180940

Abstract

Abstract:

In order to investigate the effects of hydrolysis degrees of 3-mercaptopropyltriethoxysilane (MPTS) on the grafting mechanisms of nano-silica, the grafting activities and grafting mechanisms of the hydrolyzed products in different degrees are systematically investigated based on density functional theory (DFT). The results show that the cluster model of nano-silica optimized by the GGA-PBE function is the most reasonable. The O atoms in surface silanols of nano-silica are the nucleophilic sites and the H atoms are the electrophilic sites. For MPTS and its hydrolyzed products, the O atoms are the nucleophilic sites and the Si atoms are the electrophilic sites. The LUMO orbitals shift to Si atoms and the HOMO orbitals to O atoms after hydrolysis. The electrophilic indexes of Si atoms and nucleophilic indexes of O atoms are all increased according to the Fukui function, indicating that the hydrolyzed products are more susceptible to be attacked by the surface silanols of nano-silica and the activities of grafting reaction are improved after hydrolysis. The active energies (E _a) of grafting reactions for M0—M3 follow the order of M0＞M3＞M1＞M2 (M0 is short for MPTS, M1, M2, M3 are short for the hydrolyzed products of first, second, and third order, respectively), the active energies are obviously reduced after hydrolysis. The grafting reactions of M0-M3 are S_N2 nucleophilic substitution and exothermal reactions, but the mechanisms of the grafting reactions are quite different. For M0 — M2 the grafting reactions occur via the reaction channels of eliminating ethanol, but for M3 the grafting reaction occurs via the reaction channels of eliminating H₂O. The steric hindrance and the electrophilicity of Si atoms have a significant effect on the grafting reactions of M0—M2.

Key words: computational chemistry, silica, grafting reaction, reaction kinetics, 3-mercaptopropyltriethoxysilane, hydrolysis degrees

摘要：

为探索γ-巯丙基三乙氧基硅烷(MPTS)水解程度对纳米二氧化硅接枝机理的影响，采用基于密度泛函理论(DFT)的量子化学方法，选择合适的泛函和合理的模型，系统研究了MPTS及其不同水解程度产物的反应活性及与纳米二氧化硅的接枝机理，为纳米二氧化硅改性工艺优化及改性效果的提升提供重要理论基础。结果表明：经数据对比确定GGA-PBE泛函优化后的纳米二氧化硅团簇模型为最合理模型。二氧化硅表面硅羟基中的氧原子为亲核活性中心，氢原子为亲电活性中心，MPTS及其水解产物中氧原子为亲核活性中心，硅原子为亲电活性中心。水解引起LUMO轨道向硅原子偏移，硅原子亲电指数提高，而HOMO轨道向氧原子偏移，氧原子的亲核指数提高，引起MPTS水解产物更容易受到二氧化硅表面硅羟基攻击，进而提高了接枝反应活性。MPTS的水解降低了接枝反应的活化能，不同水解程度产物接枝反应活化能(E _a)顺序为M0＞M3＞M1＞M2(M0、M1、M2和M3分别表示MPTS及其一级、二级和三级水解产物)，接枝反应属于S_N2亲核取代，且为放热反应。M0、M1和M2都是通过脱醇机理发生接枝反应，空间位阻效应和偶联剂中心硅原子的亲电性能为反应主要控制因素，而M3是通过脱水机理发生接枝反应。

关键词: 计算化学, 二氧化硅, 接枝反应, 反应动力学, γ-巯丙基三乙氧基硅烷, 水解程度

CLC Number:

O 643.12

Zhixin SHANG, Xianglan ZHANG. DFT study on effects of hydrolysis degrees of 3-mercaptopropyltriethoxysilane on grafting mechanisms of nano-silica[J]. CIESC Journal, 2019, 70(5): 1663-1673.

尚志新, 张香兰. γ-巯丙基三乙氧基硅烷水解程度对纳米二氧化硅接枝机理影响的DFT研究[J]. 化工学报, 2019, 70(5): 1663-1673.

Figures/Tables 17

Fig.1 Different types of silanols on surface of nano-silica

Fig.2 Cluster model of nano-silica (white, yellow, red ball are for H, Si, O atoms, and big purple ball are for OSiH3)

Table 1 Parameters of silanols in cluster models optimized by different functions

Model	Bond length of O—H /?	Bond length of Si—O /?	Bond angle of Si—O—H /(°)
GGA-PBE	0.970—0.981	1.624—1.653	115.8—116.6
GGA-PW91	0.969—0.986	1.620—1.656	114.7—114.9
B3LYP	0.963—0.973	1.615—1.645	114.9—115.1
cluster^[34]	0.962	1.645	114.7
slab^[38]	0.968—0.980	1.629—1.637	—

Table 2 Vibrational frequencies of silanols in cluster models optimized by different functions

Model	Types of silanol	Vibrational frequency/cm^?1
PBE	vicinal(O1—H1)	3785
PBE	vicinal H-bonded(O2—H2)	3562
PW91	vicinal(O1—H1)	3799
PW91	vicinal H-bonded(O2—H2)	3443
B3LYP	vicinal(O1—H1)	3884
B3LYP	vicinal H-bonded(O2—H2)	3677
cluster ^[37]	vicinal	3763
cluster ^[37]	vicinal H-bonded	3516
experiment^[32]	vicinal	—
experiment^[32]	vicinal H-bonded	3530

Table 3 NMR of silanols in cluster models optimized by different functions

Model	Types of silanol	δ(²⁹Si)	δ(¹H)
GGA-PBE	vicinal(O1—H1)	92.1	1.7
GGA-PBE	vicinal H-bonded(O2—H2)	92.3	4.7
GGA-PW91	vicinal(O1—H1)	95.2	1.8
GGA-PW91	vicinal H-bonded(O2—H2)	92.4	6
cluster^[37]	vicinal	86.0	—
cluster^[37]	vicinal H-bonded	86.0	3-5
experiment^[37]	vicinal	99	2
experiment^[37]	vicinal H-bonded	99	—

Fig.3 Electron density and electrostatic potential isosurface of cluster model for nano-silica

Fig.4 Electron density and electrostatic potential isosurface of M0

Fig.5 Electron density and electrostatic potential isosurface of M1

Fig.6 Electron density and electrostatic potential isosurface of M2

Fig.7 Electron density and electrostatic potential isosurface of M3

Fig.8 LUMO and HOMO orbitals of hydrolyzed products of MPTS in different degrees

Fig.9 Electrophilic index of Si and nucleophilic index of O in hydrolyzed products of MPTS in different degrees

Fig.10 PES profile of grafting reaction of M0

Table 4 Results of grafting reaction of M0 by different functions

Methods	Silane	E _a/ (kJ·mol^?1)	E _R/ (kJ·mol^?1)	Imaginary frequency/cm^?1
GGA-PBE	MPTS	99.6	?15.3	?592.8
GGA-PW91	MPTS	103.6	?27.0	?604.5
B3LYP	MPTS	125.1	?28.1	?920.9
BLYP^[25]	TEOS	154	—	—
QM/MM^[26]	TEOS	134.4	—	—
experiment^[42]	TESPT	90.4	—	—

Fig.11 PES profile of grafting reaction of M1

Fig.12 PES profile of grafting reaction of M2

Fig.13 PES profile of grafting reaction of M3

References 42

1	Basilissi L , Silvestro G D , Farina H , et al . Synthesis and characterization of PLA nanocomposites containing nanosilica modified with different organosilanes （Ⅱ）: Effect of the organosilanes on the properties of nanocomposites: thermal characterization[J]. J. Appl. Polym. Sci., 2013, 128(5): 3057-3063.
2	Liu D Y , Niu L L , Dai Y M , et al . Synthesis of poly(amidoamine) dendrimer-based dithiocarbamate magnetic composite for the adsorption of Co²⁺ from aqueous solution[J].J. Mater. Sci-Mater. El., 2018, 128(5): 3390-3397.
3	Dai Y M , Zou J Q , Liu D Y , et al . Preparation of Congo red functionalized Fe₃O₄@SiO₂ nanoparticle and its application for the removal of methylene blue[J]. Colloid. Surface. A, 2018, 550: 90-98.
4	Dai Y M , Niu L L , Zou J Q , et al . Preparation of core-shell magnetic Fe₃O₄@SiO₂ dithiocarbamate nanoparticle and its application for the Ni²⁺, Cu²⁺ removal[J]. Chinese Chemical Letters, 2018, 29(6): 887-891.
5	范艳玲, 刘艺芳, 吕雪莉, 等 . 硅酸乙酯为原料反相微乳液法制备纳米二氧化硅[J]. 化学工业与工程, 2010, 27(5): 387-390.
	Fan Y L , Liu Y F , Lyu X L , et al . Preparation of silica nanoparticles from ethyl silicate in reverse microemulsions[J]. Chemical Industry and Engineering, 2010, 27(5): 387-390.
6	Zhang C F , Tang Z H , Guo B C , et al . Significantly improved rubber-silica interface via subtly controlling surface chemistry of silica[J]. Compos. Sci. Technol., 2018, 156: 70-77.
7	Zheng J C , Han D L , Ye X , et al . Chemical and physical interaction between silane coupling agent with long arms and silica and its effect on silica/natural rubber composites[J]. Polymer, 2018, 135: 200-210.
8	Sae-oui P , Sirisinha C , Thepsuwan U , et al . Comparison of reinforcing efficiency between Si-69 and Si-264 in a conventional vulcanization system[J]. Polymer Testing, 2004, 24(4): 439-446.
9	Yrieix M , Cruz-boisson F D , Majeste J C . Rubber/silane reactions and grafting rates investigated by liquidstate NMR spectroscopy[J]. Polymer, 2016, 87: 90-97.
10	Gunji N , Komori Y , Yoshitake H . Double functionalization with mercaptopropyl and vinyl groups of the surface of silica nanoparticles and its application to tire rubber[J]. Colloid. Surface. A, 2016, 511: 351-356.
11	Thaptong P , Sea-oui P , Sirisinha C . Effects of silanization temperature and silica type on properties of silica filled solution styrene butadiene rubber (SSBR) for passenger car tire tread compounds[J]. J. Appl. Polym. Sci., 2016, 133(17): 43342.
12	Yao H , Weng G S , Liu Y P , et al . Effect of silane coupling agent on the fatigue crack propagation of silica filled natural rubber[J]. J. Appl. Polym. Sci., 2015, 132(20): 1-4.
13	Li Y , Han B Y , Liu L , et al . Surface modification of silica by two-step method and properties of solution styrene butadiene rubber (SSBR) nanocomposites filled with modified silica[J]. Compos. Sci. Technol., 2013, 88(10): 69-75.
14	Choi S S . Influence of storage time and temperature and silane coupling agent on bound rubber formation in filled styrene–butadiene rubber compounds[J]. Polymer Testing, 2002, 21(2): 201-208.
15	Blitz J P , Murthy R S S , Letden D E . The role of amine structure on catalytic activity for silylation reactions with Cab-O-Sil[J]. Colloid. Interf. Sci., 1988, 126(2): 387-392.
16	White L D , Tripp C P . Reaction of (3-aminopropyl)-dimethylethoxysilane with amine catalysts on silica surfaces[J]. Colloid. Interf. Sci., 2000, 232(2): 400-407.
17	Gauthier J P , Aime T , Bouhacina A J , et al . Study of grafted silane molecules on silica surface with an atomic force microscope[J]. Langmuir, 1996, 12(21): 5126-5137.
18	Howarter J A , Youngblood J P . Optimization of silica silanization by 3-aminopropyltriethoxysilane[J]. Langmuir, 2006, 22(26): 11142-11147.
19	Kallury K M R , Macdonald P M , Thompson M . Effect of surface water and base catalysis on the silanization of silica by alkoxysilanes studied by X-ray photoelectron spectroscopy and ¹³C cross-polarization magic angle spinning nuclear magnetic resonance[J]. Langmuir, 1994, 10(2): 492-499.
20	And A V K , Smirnov S N . Effect of water on silanization of slica by trimethoxysilanes[J]. Langmuir, 2015, 18(8): 3181-3184.
21	Pena-Alonso R , Rubio F , Rubio J , et al . Study of the hydrolysis and condensation of γ-aminopropyltriethoxysilane by FT-IR spectroscopy[J]. J. Mater. Sci., 2007, 42(2): 595-603.
22	Salon M C B , Belgacem M N . Competition between hydrolysis and condensation reactions of trialkoxysilanes, as a function of the amount of water and the nature of the organic group[J]. Colloid. Surface. A, 2010, 366(1): 147-154.
23	Salon M C B , Bayle P A , Abedlmouleh M , et al . Kinetics of hydrolysis and self-condensation reactions of silanes by NMR spectroscopy[J]. Colloid. Surface. A, 2008, 312(2): 83-91.
24	Vilmin F , Bottero I , Travert A , et al . Reactivity of bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT) silane coupling agent over hydrated silica: operando IR spectroscopy and chemometrics study[J]. J. Phys. Chem. C, 2014, 118(8): 4056-4071.
25	Iarlori S , Ceresol D , Bernasconi M , et al . Dehydroxylation and silanization of the surfaces of β-cristobalite silica: an ab initio simulation[J]. J. Phys. Chem. B, 2001, 105(33): 8007-8013.
26	Zipoli F , Donadio D , Bernasconi M . Simulation of the grafting of organosilanes at the surface of dry amorphous silica[J]. J. Phys. Condens. Mat., 2008, 20(22): 224011.
27	Deetz J D , Ngo Q , Faller R . Reactive molecular dynamics simulations of the silanization of silica substrates by methoxysilanes and hydroxysilanes[J]. Langmuir, 2016, 32(28): 7045-7055.
28	Potapov V V , Zhuravlev L T . Concentration of various forms of water in silica precipitated from a hydrothermal solution[J]. J. Volcanol. Seismol., 2007, 1(5): 310-318.
29	Zhuravlev L T . The surface chemistry of amorphous silica[J]. Colloids Surfaces A, 2000, 173(1/2/3): 1-38.
30	Bandura A V , Kubicki J D , Sofo J O . Periodic density functional theory study of water adsorption on the α-quartz (101) surface[J]. J. Phys. Chem. C, 2011, 115(13): 6756-6766.
31	Yang J , Wang E G . Water adsorption on hydroxylated α-quartz (0001) surfaces: from monomer to flat bilayer[J]. Phys. Rev. B, 2006, 73(3): 35406.
32	Taylor D C E , Runge K , Cory M G , et al . Binding of small molecules to a silica surface: comparing experimental and theoretical results[J]. J. Phys. Chem. C, 2015, 115(50): 24734-24742.
33	Yang L X , Feng J , Zhang W G , et al . Film forming kinetics and reaction mechanism of γ-glycidoxypropyltrimethoxysilane on low carbon steel surfaces[J]. Appl. Surf. Sci., 2010, 256(22): 6787-6794.
34	Del R I , Gerber I C , Poteau R , et al . Grafting of lanthanide complexes on silica surfaces: a theoretical investigation[J]. J. Phys. Chem. A, 2010, 114(21): 22-30.
35	Bermudez V M . Computational study of the adsorption of trichlorophosphate, dimethyl methylpho-sphonate, and sarin on amorphous SiO₂ [J]. J. Phys. Chem.C, 2007, 111(26): 9314-9323.
36	Chashchikhin V , Rykova E , Bagaturyants A . Density functional theory modeling of the adsorption of small analyte and indicator dye 9-(diphenylamino)acridine molecules on the surface of amorphous silica nanoparticles[J]. Phys. Chem. Chem. Phys., 2011, 13(4): 1440-1447.
37	Rosal I D , Gerber I C , Poteau R , et al . Grafting of lanthanide complexes on silica surfaces dehydroxylated at 200 degrees: a theoretical investigation[J]. New J. Chem., 2015, 39(10): 7703-7715.
38	Musso F , Sodupe M , Corno M , et al . H-bond features of fully hydroxylated surfaces of crystalline silica polymorphs: a periodic B3LYP study[J]. J. Phys. Chem. C, 2009, 113(41): 17876-17884.
39	Yang L X , Feng J , Zhang W G , et al . Experimental and computational study on hydrolysis and condensation kinetics of γ-glycidoxypropyltrimethoxysilane (γ-GPS)[J]. Appl. Surf. Sci., 2010, 257(3): 990-996.
40	Cheng X L , Zhao Y Y , Liu Y J . Role of F⁻ in the hydrolysis–condensation mechanisms of silicon alkoxide Si(OCH₃)₄: a DFT investigation[J]. New J. Chem., 2013, 37(5): 1371-1377.
41	于莉, 程学礼, 赵燕云 . 酸性条件下硅醇盐Si(OCH₃)₄水解与聚合机理的密度泛函研究[J]. 高分子学报, 2013, 71(1): 118-125.
	Yu L , Cheng X L , Zhao Y Y . Hydrolysis and oligomerization mechanisms of Si(OCH₃)₄ in acid solutions: a DFT investigation[J]. Acta. Polyme. Sin., 2013, 71(1): 118-125.
42	Liu J W , Li C , Sun C , et al . Insights into the silanization processes of silica with and without acid-base additives via TG-FTIR and kinetic simulation[J]. Ind. Eng. Chem. Res., 2017, 56(18): 5164-5173.

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