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

doi:10.11949/j.issn.0438-1157.20180940

摘要/Abstract

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

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

中图分类号:

O 643.12

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.

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.

图/表 17

图1 纳米二氧化硅表面不同类型羟基

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

图2 纳米二氧化硅团簇模型 (白色、黄色、红色的球分别代表氢、硅和氧原子，紫色大球代表OSiH3)

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

表1 不同泛函优化后纳米二氧化硅模型硅羟基参数

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	—

表2 不同泛函优化后纳米二氧化硅模型硅羟基振动频率

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

表3 不同泛函优化后纳米二氧化硅模型硅羟基NMR数据

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	—

图3 纳米二氧化硅团簇模型电子密度和静电势等值面图

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

图4 M0电子密度和静电势等值面图

Fig.4 Electron density and electrostatic potential isosurface of M0

图5 M1电子密度和静电势等值面图

Fig.5 Electron density and electrostatic potential isosurface of M1

图6 M2电子密度和静电势等值面图

Fig.6 Electron density and electrostatic potential isosurface of M2

图7 M3电子密度和静电势等值面图

Fig.7 Electron density and electrostatic potential isosurface of M3

图8 MPTS不同水解程度产物LUMO和HOMO轨道

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

图9 MPTS不同水解程度产物中硅原子亲电指数和氧原子亲核指数

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

图10 M0接枝反应的PES图

Fig.10 PES profile of grafting reaction of M0

表4 不同泛函下M0接枝反应数据表

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	—	—

图11 M1接枝反应的PES图

Fig.11 PES profile of grafting reaction of M1

图12 M2接枝反应的PES图

Fig.12 PES profile of grafting reaction of M2

图13 M3接枝反应的PES图

Fig.13 PES profile of grafting reaction of M3

参考文献 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.

[1]	程成, 段钟弟, 孙浩然, 胡海涛, 薛鸿祥. 表面微结构对析晶沉积特性影响的格子Boltzmann模拟[J]. 化工学报, 2023, 74(S1): 74-86.
[2]	陈美思, 陈威达, 李鑫垚, 李尚予, 吴有庭, 张锋, 张志炳. 硅基离子液体微颗粒强化气体捕集与转化的研究进展[J]. 化工学报, 2023, 74(9): 3628-3639.
[3]	汪林正, 陆俞冰, 张睿智, 罗永浩. 基于分子动力学模拟的VOCs热氧化特性分析[J]. 化工学报, 2023, 74(8): 3242-3255.
[4]	张蒙蒙, 颜冬, 沈永峰, 李文翠. 电解液类型对双离子电池阴阳离子储存行为的影响[J]. 化工学报, 2023, 74(7): 3116-3126.
[5]	何晓崐, 刘锐, 薛园, 左然. MOCVD生长AlN单晶薄膜的气相和表面化学反应综述[J]. 化工学报, 2023, 74(7): 2800-2813.
[6]	李晨曦, 刘永峰, 张璐, 刘海峰, 宋金瓯, 何旭. O₂/CO₂氛围下正庚烷的燃烧机理研究[J]. 化工学报, 2023, 74(5): 2157-2169.
[7]	任金胜, 刘克润, 焦志伟, 刘家祥, 于源. 涡流空气分级机近导叶处团聚体解团机理研究[J]. 化工学报, 2023, 74(4): 1528-1538.
[8]	葛运通, 王玮, 李楷, 肖帆, 于志鹏, 宫敬. 多相分散体系中微油滴与改性二氧化硅表面间作用力的AFM研究[J]. 化工学报, 2023, 74(4): 1651-1659.
[9]	禹进, 余彬彬, 蒋新生. 一种基于虚拟组分的燃烧调控化学作用量化及分析方法研究[J]. 化工学报, 2023, 74(3): 1303-1312.
[10]	陈晨, 杨倩, 陈云, 张睿, 刘冬. 不同氧浓度下煤挥发分燃烧的化学动力学研究[J]. 化工学报, 2022, 73(9): 4133-4146.
[11]	戴文华, 辛忠. Si掺杂对Cu/ZrO₂催化CO₂加氢制甲醇性能的影响[J]. 化工学报, 2022, 73(8): 3586-3596.
[12]	俞夏琪, 冯格, 赵金燕, 李嘉远, 邓声威, 郑靖楠, 李雯雯, 王亚秋, 沈榄, 刘旭, 徐威威, 王建国, 王式彬, 姚子豪, 毛成立. 基体（TDI-TMP-T313）与氧化剂（AP）相互作用的第一性原理研究[J]. 化工学报, 2022, 73(8): 3511-3517.
[13]	张鑫, 许蕊, 路馨语, 牛永安. SiO₂@BiOCl-Bi₂₄O₃₁Cl₁₀核壳微球的合成及光催化[J]. 化工学报, 2022, 73(8): 3636-3646.
[14]	刘晓涯, 王金超, 刘莹, 马敬环. 水合肼制氢纳米催化剂改性制备及机理研究进展[J]. 化工学报, 2022, 73(7): 2819-2834.
[15]	陈玉弓, 陈昊, 黄耀松. 基于分子反应动力学模拟的六甲基二硅氧烷热解机理研究[J]. 化工学报, 2022, 73(7): 2844-2857.