A type of silicone modified styrene-acrylate latex for weatherable coatings with improved mechanical strength and anticorrosive properties

Journal Pre-proof A type of silicone modified styrene-acrylate latex for weatherable coatings with improved mechanical strength and anticorrosive properties

Yumin Wu, Chuancong Zhu, Zhengzhe Yanchen, Hui Qiu, Haoyuan Ma, Chuanhui Gao, Yuetao Liu PII:

S1381-5148(19)31124-1

DOI:

https://doi.org/10.1016/j.reactfunctpolym.2020.104484

Reference:

REACT 104484

To appear in:

Reactive and Functional Polymers

Received date:

22 October 2019

Revised date:

4 January 2020

Accepted date:

6 January 2020

Please cite this article as: Y. Wu, C. Zhu, Z. Yanchen, et al., A type of silicone modified styrene-acrylate latex for weatherable coatings with improved mechanical strength and anticorrosive properties, Reactive and Functional Polymers (2019), https://doi.org/ 10.1016/j.reactfunctpolym.2020.104484

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© 2019 Published by Elsevier.

Journal Pre-proof

A type of silicone modified styrene-acrylate latex for weatherable coatings with improved mechanical strength and anticorrosive properties Yumin Wu, Chuancong Zhu, Zhengzhe Yanchen, Hui Qiu, Haoyuan Ma, Chuanhui Gao, Yuetao Liu* [email protected] State Key Laboratory Base for Eco-Chemical Engineering in College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, China

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Abstract

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In this study, a type of silicone modified styrene-acrylate latex (SSA) was synthesized by styrene (St), vinyl trimethoxysilane (VTMS) and isooctyl acrylate (IA) through RAFT emulsion

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polymerization. The molecular weight and distribution (PDI) of SSA increased with VTMS

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contents ranging from 0 to 4 %. It also enhanced the tensile strength of SSA coatings from 3.6 to 5.8MPa. Furthermore, SSA coatings possessed the good self-healing properties. TGA and

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DMA indicated the thermal stability of SSA coatings increased with the increasing of VTMS

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contents. It also increased the water contact angle (CA) from 85 to 105 ° and reduced the water absorption from 3.75 to 0.8 %. The open circuit potential (Eocp)-time and anodic polarization

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(Tafel) curves indicated the corrosion resistance enhanced with the increase of the VTMS contents. The all obtained results indicated the SSA would have great potential as weatherable and anticorrosive coatings.

Keywords Silicone

modified

styrene-acrylate

latex;

Mechanical

performance;

Weatherability;

Anticorrosion; Self-healing properties.

1. Introduction Styrene acrylate latex (SA), as a good candidate for weather–resistant coatings, has been widely used in the interior and exterior decorations of building, papermaking and corrosion protection of metals, etc. [1]. Nowadays, more and more attentions are focused on the modification to improve the bond strength, water resistance and film-forming property of SA, such as silicone modification [2], [3], epoxy modification [4] and phosphorus modification [5].

Journal Pre-proof Among them, silicone modification was the most widely used method that silicone could be used as coating modifier or cross-linking agent due to the good thermal stability, comprehensive hardness and hydrophobicity, which had attracted the attention of the masses and the favor of researchers [6], [7], [8], [9]. Nowadays, lot of related works had been done. For example, the vinyl triethoxysilane modified SA coating could improve the softening coefficient and compressive strength of gypsum and reduced the water absorption [10]. Xiao et al. [11] prepared an aqueous semi-gloss SA with 1,1,1,3,5,5,5-heptamethyltrisiloxane as modifier which had good the water wetting and

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scrub resistance properties. Wang et al. [12] prepared cationic silicone-acrylic latexes by vinyl

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trisopropoxy silane and the type of coating had improved water resistance and mechanical properties. BAO et al. [13] used allyl alkoxy phosphateand 3-methacryl oxypropyltrimethoxy

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silane to obatin the phosphorus acrylic latex which possessed the excellent thermal stability.

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Although the good water resistance, mechanical properties and thermal stability could be obtained by the chemical modification of silicone, the self-healing and the anticorrosive

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properties of SA were seldom focused.

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The silanol bond obtained by the hydrolysis of the silane and the carboxyl group could form the hydrogen bond interactions, and the acidic polymerization conditions was more

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favorable for the hydrolysis of the silane [14], [15]. As we known, the hydrogen bond was a type of thermally reversible interaction which could endow the self-healing properties and thermoplasticity of coatings [16]. In order to increase the hydrogen bonding crosslink density and provide an acidic polymerization environment, the RAFT reagent containing carboxylate was chosen for SSA emulsion polymerization. Water as dispersion medium was a reasonable RAFT polymerization method and the emulsion was environmental friendly [17]. In addition, RAFT polymerization was proved to be successful method in emulsion systems and it already had a wider range of suitable monomers [18], [19], [20]. Herein, silicone modified styrene-acrylate latex (SSA) was firstly synthesized by styrene(St), vinyl trimethoxysilane (VTMS) and isooctyl acrylate (IA) through RAFT emulsion polymerization. The yellow crystal of 2-[(dodecylsulfanyl)-carbo–nothioyl] sulfanyl propanoic acid (DSCPA) was used as the RAFT agent. Then, the chemical structure, the morphology, the conversion and gel fraction, the molecular weight and distribution, the particle size and

Journal Pre-proof distribution of SSA were measured. The mechanical properties, self-healing properties, thermal properties, anticorrosive properties and hydrophobic properties of SSA coatings were also investigated. We expected the obtained SSA would have improved mechanical strength and anticorrosive properties as a type of weatherable and anticorrosive coatings.

2. Experimental 2.1. Materials Styrene (St, 99%) and isooctyl acrylate (IA, 99%) were purchased from Shanghai Maclean

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Biochemical Technology Co., Ltd. vinyltrimethoxysilane (VTMS, 99%) was purchased from

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Shanghai Aladdin Biochemicals Technology Co., Ltd. Polyoxyethylene octylphenol ether-10 (OP-10, 99%) and sodium lauryl sulfate (SDS, 92.5%) were purchased by Tianjin Bodi

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Chemical Co., Ltd. Potassium persulfate (KPS, 99.5%) was purchased from Tianjin Hengxing

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Chemical Reagent Manufacturing Co., Ltd. 2–[(dodecylsulfanyl)carbo–nothioyl] sulfanyl

Algi Serelis et al [21].

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propanoic acid (DSCPA) was synthesized and purified according to the method described by

2.2. Preparation of SSA coatings

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For a typical synthetic scheme, 0.10 g (3.00×10–4 mol) DSCPA was dissolved in the mixed

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monomers of 9.50 g (9.12×10–2mol) St, 7.10 g (3.85×10–2 mol) IA, and 0.60 g (4.08×10–3 mol) VTMS to form the mixed solution. Then, the mixed solution, 0.30 g of OP-10, 0.30g SDS and 41.5 g (31.40 mL) deionized water were mixed in the beaker and stirred under the ultrasonic waves to form the pre-emulsion. 0.12 g (4.44×10–4 mol) KPS was dissolved in 4.0 g (4.15 mL) deionized water and it was divided into two parts. One third of the pre-emulsion was added to a 250 mL four-neck round bottom glass flask with N2 and a mechanical stirrer. After the temperature was raised to 80 °C, KPS aqueous solution was added dropwisely into the mixture within 10 min. After the reaction was carried out for 20 minutes, the residual KPS aqueous solution and the pre-emulsion were drop wised to the mixture simultaneously within 20 min. After that, it continued to reaction for another 1 h and ammonia water was added to the emulsion slowly until the pH of latex was 7. The specific formulation, the conversion C (%) and gel fraction G (%) of SSA were shown in Table 1. The dumbbell-shaped coating was obtained by casting the latex on a polytetrafluoroethylene sheet and after vacuum drying at 80 °C. The

Journal Pre-proof preparation route and schematic illustrations were schematically presented in Scheme 1. Table 1. Formulations and properties of SSA with different VTMS contents. 𝐺 (%)a Mn (g/mol)b Mw (g/mol)b

PDIb

[VTMS] (mol/mol)

C (%)a

SSA-0

0%

93

3.7

89652

109375

1.22

SSA-1

1%

92

3.8

133033

187577

1.41

SSA-2

2%

91

4.3

169645

276521

1.63

SSA-3

3%

92

4.9

195297

333958

1.71

SSA-4

4%

90

6.2

232569

530257

2.28

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Sample

a Determined by gravimetrically.

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b Determined by GPC analysis.

Scheme 1. The preparation route and schematic illustrations of SSA coating.

3. Characterizations 3.1 Determination of conversion C (%) and gel fraction 𝐺 (%) The parameters such as 𝐶 and 𝐺 were determined gravimetrically using eqs 1 and 2. 𝐶 (%) = [𝑀2 𝑚1 (1 − 𝑊1 )/𝑚2 + 𝑀1 (1 − 𝑊1 )]/𝑀 × 100%

(1)

𝐺 (%) = 𝑀1 (1 − 𝑊1 )/𝑀 × 100%

(2)

Journal Pre-proof Where, 𝑚1 is the weight of the coating after dried, and 𝑚2 is the weight of the coating before dried. 𝑀1 is the weight of the gel, 𝑀2 is the weight of the whole latex and 𝑀 is the weight of all monomers. 𝑊1 is the proportion of non–volatile impurity components.

3.2 1H NMR 1

H NMR was conducted with a AVANCE 400 spectrometer (Bruker, Germany) at room

temperature using CDCl3 as the solvent and without tetramethylsilane as an interior label.

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3.3 FTIR The chemical structure of SSA was identified by the Fourier transform infrared

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spectroscopy (Nicolet 6700/Nicolet Continuum FTIR spectrometer, Thermo Fisher Scientific

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Inc.). Each spectrum was recorded by performing 64 scans between 4000 and 500 cm−1.

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3.4 GPC

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The GPC characterization was performed on a waters 1525 instrument with a detector of waters 2414 and a column of Agilent PLgel 5um MIXED-C (made in GB). SSA were dissolved

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in THF at a concentration of 5 mg/ml. THF was used as the eluent at a flow rate of 1 ml/min.

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3.5 Dynamic light scattering (DLS)

The particle size and size distribution (PDI) were measured by Malvern nano ZS instrument (Malvern Instruments, UK) at room temperature with a fixed scattering angle of 90 °. For the detection, SSA was diluted by deionized water to 10 mg/ml and under sonification for 10 min at 25 °C.

3.6 TEM The surface morphology of SSA was observed using a transmission electron microscope (TEM, JEM-2100F, Japan) at a voltage of 80-200 kV. The latex was diluted with deionized water, dripped onto the copper net and dyed with 5% (mass fraction) phosphotungstic acid.

3.7 Mechanical test The tensile strength was measured by an electronic universal testing machine (manufactured by Shenzhen Science and Technology Co., Ltd., China) based on ASTM D412

Journal Pre-proof standards at 25±2 °C at 10 mm/min, and the thickness and width of the sample were measured by a vernier caliper.

3.8 Crosslink density test The crosslinking density of SSA coating was calculated via the equilibrium swelling method. SSA (about 0.08 g) and toluene (10 mL) were put into a sealed vessel at 25 °C. After being immersed in toluene for 6 h, the samples were weighed after being blotted with filter paper to remove the excess toluene and then immersed into toluene again. This step was

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repeated every 1 h until the swelling equilibrium was obtained. The cross-linking density 𝛾𝑒 is

𝜑 = (𝑤o /𝜌)/[(𝑤𝑠 − 𝑤o )/𝜌1 + 𝑤o /𝜌] 1

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calculated using eqs 3 and 4.

𝜑

(4)

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𝛾𝑒 = 𝜌/𝑀𝐶 = −[𝐼𝑛(1 − 𝜑) + 𝜑 + 𝜒1 𝜑 2 ]/[𝑉𝑜 (𝜑 3 − 2 )]

(3)

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Where, 𝜑 is the volume fraction, 𝑤o is the weight of the original sample, 𝜌 is the density of the SSA before swelling, 𝑤𝑠 is the swollen weight of the SSA, 𝜌1 is the density of

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the toluene (0.87 g/cm3). Term 𝛾𝑒 is the cross-linking density, 𝑀𝐶 is the average molecular weight between cross-linking point, 𝜒1 is the interaction parameter of polymer and solvent

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3.9 SEM

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(0.34); 𝑉𝑜 is the molar volume of toluene (106.54 cm3/mol) [22], [23], [24].

A scanning electron microscopy (SEM; JEOL, model JSM-7001F) was used to observe the cross-sections of fractured SSA coatings. The samples were frozen by liquid nitrogen and fractured using tweezers to produce cross-sections. The cross-sections were then coated with gold and sent for SEM observation using an accelerating voltage of 20 kV.

3.10 Self-healing properties After the dumbbell-shaped samples were cut into two pieces, bringing them together insitu and the broken sections were pressed with a 100 g weight. Then it was put into a dry oven at 80 °C for 12 hours. The biological binocular microscope (XSP-4C) was used to observe the healing state of the fracture surface of coatings. The tensile strength was again measured according to electronic universal testing machine.

3.11 TGA

Journal Pre-proof Thermogravimetric analysis (TGA) was performed using a TG (SDT-Q600, TA) instrument under N2 atmosphere. Each sample was scanned from the room temperature to 600 °C at a heating rate of 5 °C/ min.

3.12 DMA The tangent value (tanσ) was estimated using a dynamic thermomechanical analysis (DMA) Q800 analyzer (TA Instrument, USA) from 20 to 60 °C with a heating rate of 5°C/min under N2 atmosphere.

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3.13 AFM

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The surface morphology of SSA coating was collected using a AFM in AC mode with an AFM cantilever (Nano World, PointProbe Plus - Silicon SPM Sensor) and the spring constant

3.14 Water contact angle (CA)

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at 25 °C and a relative humidity of 50 %.

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was measured using the thermal noise method to be 33 N/m. The measurement was performed

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(static, standard type, SZ-CAMB).

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The water contact angle of the coatings was measured using a static contact angle meter

3.15 Water absorption rate

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The coatings immersed in distilled water at 25 °C. At specific time intervals, the water on the surface of the coatings removed with a paper towel. The weight was calculated by eq 5. 𝑊(%) = (𝑚1 − 𝑚0 )/𝑚0 × 100%

(5)

Where, 𝑊 is the water absorption rate of the coating, 𝑚0 and 𝑚1 represent the weight of the coating after and before water absorption.

3.16 Electrochemical measurement Three-electrode system was used and the electrolyte is 3.5 % NaCl solution. The auxiliary electrode is platinum electrode. The reference electrode is a saturated calomel electrode. The working Electrode was sample. The scanning range of Eocp-Time and Tafel curve measurement are open-circuit potential (-0.1-2 V) and the scanning rate is 5 mV/s.

4. Results and Discussion

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4.1. Structure characterization As the building substrates in finishing application was hard and absorbent materials, the coatings must be relatively rigid to be compatible with the substrate [25], [26]. Hence in view of the tensile strength, hydrophobicity and adhesion of the coatings, the base monomers of isooctyl acrylate (IA) and styrene(St) were chosen as the soft and hard monomers, which were responsible of the hardness and thermoplastic of the coatings. Vinyl trimethoxysilane (VTMS) was selected as a functional monomer to improve the crosslink density of the coatings through

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the hydrogen and chemical bonds. [10], [27], [28]. FTIR characterization of the SSA was shown in Fig. 1(a). It was noted that the stretching

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vibrations of C=O was clearly appeared at 1731 cm-1. The peaks from 2922 to 2870 cm-1 were

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assigned to the saturated C-H and the peak at 3030 cm-1 was due to the unsaturated C-H of phenyl. Furthermore, the weak absorption peaks at 845 cm-1 ascribed to the Si-C bonds

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increased with the increasing of VTMS, and the weak absorption peaks at 1020 cm-1 ascribed

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to the Si-O-Si bonds increased with the increasing of VTMS. The formation of Si-O-Si bonds was due to the condensation of Si-O-H that was hydrolyzed by Si-O-CH3. The peak at 3472 cmwas caused by the hydroxyl group and the peaks became stronger with the increasing of VTMS

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contents. These results indicated VTMS monomer was copolymerized with St and IA by the

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unsaturated bond [29], [30], [31].

To further demonstrate the successful introduction of VTMS to SSA, SSA-4 latex was chosen to conduct 1HNMR characterization. The result was added and shown in Fig. 1(b). The peaks at 1.51 ppm (a) corresponded to the methine at Si-C bonds were also observed. The characteristic peaks of methoxy groups could be observed at 3.72 ppm (b). The peaks at 7.12 ppm (c) corresponded to the phenyl were also observed. The carboxyl group contain active hydrogen, which was prone to hydrogen-deuterium exchange with the solvent, did not appear. As shown in Table 1 and Fig. 1(c), the successful polymerization of VTMS with St and IA had a considerable impact on the molecular weight and distribution of SSA. With the increasing of VTMS contents, the PDI, Mn and Mw of SSA gradually increased. This was due to the crosslinking bonds in VTMS not conducive to the molecular weight controllability of DSCPA. However, the carboxyl group in DSCPA improved other properties of SSA coating, such as

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mechanical and repair properties.

Fig. 1. (a) FT-IR spectra of SSA with different VTMS contents; (b) 1H NMR of SSA-4 latex and (c) molecular weight and distribution curves of SSA with different VTMS contents.

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4.2. Emulsion properties Fig. 2 showed the emulsion characteristic and TEM images of SSA with different VTMS contents. It was noted that the average particle size of SSA increased with VTMS contents ranging from 0% to 4% [15]. This was attributed to the fact that the silanol bond produced by the hydrolysis of VTMS could be dehydrated and condensed to cause partial adhesion between the particles, and resulting in the formation of larger particle sizes. To further validate the data from the laser particle size instrument, TEM was carried out and the results were also presented

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in Fig. 2(a). It was observed that SSA particles had a tendency to adhesion. So the particle size increased as the increasing of VTMS contents. In addition, the increase of VTMS contents

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caused the particle size distribution (size PDI) to increase first. When the VTMS contents

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exceeded 2%, size PDI then decreased. The results were shown in Fig. 2(b). There was a large number of small and large particles at the same time, resulting in higher PDI of SSA-2 latex.

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When VTMS contents continued to increased, the large particles accounted for the main

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component and caused size PDI gradually decreased. The reason might be the cross-linking of

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Si-O-Si bonds led to a transition from small particle dominated to large particle in latex [32].

Journal Pre-proof Fig. 2. The emulsion characteristics and TEM of SSA with different VTMS contents.

4.3. Mechanical properties Fig. 3 showed the stretching process, the stress-strain curves, the crosslinking density and SEM of SSA coatings with different VTMS contents. It could be clearly observed from Fig. 3(a) that SSA coatings could be stretched. The stress-strain relationship of SSA coatings were significantly improved by the introduction of VTMS. When the VTMS contents ranged from 0 to 4 wt%, the breaking stress increased from 3.6 to 5.8 MPa, which was shown in Fig. 3(b). The

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crosslinking density of SSA coating was also tested by the equilibrium swelling method in toluene, and the results were shown in Fig. 3(c). It was noted that the crosslinking density

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increased with the increasing of VTMS contents. The initial increase of crosslinking density

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benefited the improvement of the stress and strain of SSA coatings. However, the higher crosslinking density was not conducive to the increase of strain which meant the higher

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crosslinking density caused the coating hard and brittle. So the strain first increased and then

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decreased which was due to the increase of the crosslinking density. SEM was performed to determine the morphological changes of SSA coatings fractured

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cross section with different VTMS contents and the results could be seen in Fig. 3(d). It was observed that SSA-0 was smooth and had almost no streaks protrusion, which was attributed to

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its lack of stronger crosslinking network. More streaks were formed on the fracture surface of the SSA coatings with VTMS contents ranging from 1 to 4%. SSA-4 had the most stripes, which could be explained by the presence of a large number of crosslinks that made the coating difficult to pull. The SEM results were also in according with the strain-stress results.

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Fig. 3. (a) The stretching process of SSA-3 coating; (b) the stress-strain curves, (c) crosslinking density and (d) SEM of SSA coatings with different VTMS contents.

4.4. Self–healing properties Fig. 4 showed the self-healing properties of SSA coatings. A crack was made on the coatings using a knife and then thermally treated at 80 °C for 2, 6, 10 and 12 h. The self-healing state of SSA-3 coating was shown in Fig. 4(a), the healed sample were stretched and bended without breaking at the cutting position. It could be observed in Fig. 4(b) that the crack migrated

Journal Pre-proof with time and it had a continuous self-healing phenomenon and completely healed within 12 hour although minor scars were still visible. The healed coating was used to the tensile test and the results were shown in Fig. 4(c). Clearly, the tensile strength of sample was recovered at 80 °C for 12 h. The self-healing efficiency of the strain of SSA-2 coating and the stress of SSA4 coating reached 81.0% and 76.9%, respectively. The self-healing properties of the SSA coatings had no significant influence with the increasing of VTMS contents which could be explained by the fact that the dynamic thermoreversible hydrogen bond formation and the thermoplastic properties [16]. The possible self-healing mechanism of the SSA coatings was

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also shown in Fig. 4(d).

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Fig.4 (a) Self-healing state and (b) self-healing process of SSA-3 coating; (c) The healing stressstrain curves and efficiency of SSA coatings with different VTMS contents and (d) self-healing mechanism of SSA coatings.

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4.5. Thermodynamic properties To determine the influence of VTMS contents on the thermal stability of SSA coatings, TGA analyses were carried out and the results were shown in Fig. 5(a). It was noted that the thermal degradation was occurred at the range of 339 to 435 °C due to the random chain scission. The coatings with different amounts of VTMS exhibited similar thermal behavior. The increase of VTMS contents caused the incomplete degradation of the samples. There was 23 wt% residue of SSA-4 at 500 °C indicating that the coatings had some residue due to the presence

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of a partially larger chemical and hydrogen bonding crosslinking network. The temperature corresponding to the tangent inflection point in DMA was the glass transition temperature (Tg)

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of the SSA coatings. The DMA curves appeared distinctions that Tg raised from 35.1 to 40.9 °C

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with the increase of VTMS contents in Fig. 5(b). As we known, network polymers had higher Tg than linear polymers [33]. Moreover, the steric hindrance of VTMS and hydrogen bond

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between SSA cross-linking network also caused the increase of the internal interaction and the

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increase of Tg [34]. In addition, SSA coatings had only one Tg and no other secondary transition temperature was observed. It indicated that there was no phase separation and the copolymer

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was mainly random copolymerization.

Fig. 5. (a) TGA and (b) DMA curves of SSA coatings with different VTMS contents.

4.6. Water resistance analysis The water contact angle (CA) and the water absorption were commonly used for the evaluation of hydrophobicity of latex coatings [35]. In order to reduce the effect of surface roughness on water CA, we tried our best to prepare SSA coatings under the same conditions.

Journal Pre-proof In addition, SSA-0 and SSA-2 (respectively represented VTMS modification or not) were chosen to perform AFM characterization. The result was added in Fig. 6(a). It illustrated that the depth and height of the roughened surfaces of the two coatings were little difference. So we thought the surface roughness was not main influencing factor of water CA [36]. The water CA and water absorption of SSA coatings with different VTMS contents were investigated and the results were shown in Fig. 6(b). The water CA and water absorption increased from 85 to 105 ° and decreased from 3.8 to 0.7 % with VTMS contents ranging from 0 to 4 %, respectively. All the results indicated that the water resistance were evidently enhanced due to the introduction

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of VTMS. It might be attributed to the excellent hydrophobicity of the Si–O–Si bond [14]. In

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addition, a photograph of the SSA-4 latex and its water resistance application on a cement substrate is shown in Fig. 6(c). It was noted that the latex was uniform and stabile in the dilution

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process. SSA-4 latex was then applied to a cement substrate to form a coating to simulate the

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building interior or exterior coating. The surface of the substrate was divided into two parts and water was dropped on. It was found that the coatings could improve the hydrophobic properties

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of cement substrate significantly. The results indicated the SSA would have great potential as

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weatherable coatings for interior and exterior decorations of building.

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Fig. 6. (a) AFM images of SSA-0 and SSA-2 coating surfaces; (b) Water CA and absorption rate of SSA coatings with different VTMS contents; (c) Application of SSA on the cement

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4.7. Anticorrosive properties In order to compare the stability and protection efficiency of SSA coatings under polarized conditions, the open circuit potential (Eocp)-time and anodic polarization (Tafel) curves were further instigated and the results were given in Fig. 7. As shown in Fig. 7(a), the SSA coatings electrode after 72 hours of immersion had more stable Eocp value than the bare electrode and it shifted corrosion potential of copper to the positive potential. This trend was related to the

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physical barrier effect of the SSA coatings [37]. The Tafel curves shown in Fig. 7(b), the SSA coatings decreased the current density values as it restricted the mass transfer between copper

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and chloride containing corrosive solution, hence decreased the corrosion rate of copper.

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Furthermore, The SSA-4 exhibited better stability at high potential values that was determined by the fact that SSA-4 had the highest crosslink density and a dense protective coating adhered

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to the surface of the copper.

Fig. 7. (a) Eocp -Time and (b) Tafel curves of Cu and Cu/SSA coatings

5. Conclusion A type of silicone modified styrene-acrylate latex (SSA) was successfully synthesized by styrene(St), vinyl trimethoxysilane (VTMS) and isooctyl acrylate (IA) through RAFT emulsion polymerization. FTIR and 1H NMR results manifested the successful introduction of VTMS into the main chains. The molecular weight and distribution (PDI) of SSA increased with the increasing of VTMS contents. The increase of VTMS contents also increased the SSA particle

Journal Pre-proof from 52.8 to 80.7 nm. The size PDI increased first and then decreased with VTMS contents ranging from 0 to 4 %. It enhanced the tensile strength of SSA coatings from 3.6 to 5.8 MPa. It led to the self-healing properties and the self–healing efficiency could be up to 81%. Also, it improved the hydrophobic properties, increased the thermal stability and raised Tg from 35.1 °C to 40.9 °C. In addition, it shifted corrosion potential of copper to the positive potential and enhanced the corrosion resistance. The obtained results indicated the SSA would have great potential as weatherable and anticorrosive coatings.

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Data Availability The raw/processed data required to reproduce these findings can not be shared at this time

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Declaration of Competing Interest

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due to technical or time limitations.

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The authors declare that they have no known competing financial interests or personal

Acknowledgments

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relationships that could have appeared to influence the work reported in this paper.

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This work was supported by Shandong Provincial Natural Science Foundation (ZR2019QB019), National Natural Science Foundation of China (51872150), Shandong

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Provincial Natural Science Foundation (ZR2018MB034), Talent Fund of Shandong Collaborative Innovation Center of Eco-Chemical Engineering (XTCXQN11), Open Subject Fund of State Key Laboratory Base for Eco-Chemical Engineering in College of Chemical Engineering (STHG1804).

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Author Statement 1. The research results reported in this article are the original research results of myself or all of the research team. Except for the places marked specially by the author of this article, the research results published or written but not yet published by others are not included in the article. No infringement of the intellectual property rights of others or other copyright owners. 2. This article contains no political errors, nor does it involve state secrets or any sensitive issues that should not be published publicly.

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3. The author recognizes the importance of the commitments embodied in this statement and

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bears all the consequences of breaching this commitment.

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Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal

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relationships that could have appeared to influence the work reported in this paper.

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Highlights 

The mechanical property of the styrene-acrylate coating was enhanced by silicone.

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A silicone coating having repair properties was prepared by RAFT polymerization.

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A silicone coating having improved thermal stability, water resistance, and corrosion

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resistance was prepared.