One-step synthesis and properties of SiO2/polystyrene hydrophobic composite microspheres
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摘要: 提出了以苯乙烯、二乙烯基苯和γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)为单体,通过伴随着溶胶-凝胶反应的悬浮聚合法一步制备表面构筑有SiO2粗糙结构的交联聚苯乙烯微球(SiO2/聚苯乙烯疏水复合微球)。研究了油相组成、KH570用量和溶胶-凝胶反应条件对SiO2/聚苯乙烯疏水复合微球强度和疏水性能的影响。结果表明,当弃除油相中的溶剂甲苯,在50℃的恒温反应阶段采用氨水调控体系pH值为10~11时可以获得兼具持久疏水性能、高强度和超低密度的SiO2/聚苯乙烯疏水复合微球。SiO2/聚苯乙烯疏水复合微球的表观密度约0.9917 g∙cm−3,69 MPa的闭合压力下破碎率低至2.53%,表面静态水接触角高达140.7°,耐热性能优异(玻璃化转变和分解温度分别高达160℃和390℃)。尤其是,在涠州X油田A5井的螯合酸HD和FA中持续回流30天的过程中,SiO2/聚苯乙烯疏水复合微球表面的接触角变化仍分别保持在±10%和±7%以内。SiO2/聚苯乙烯疏水复合微球具备作为深部储层开采用支撑剂的极大潜力,也可用作封隔体控水工艺中的充填材料。Abstract: The styrene, divinylbenzene and KH570 were used as monomers to preparer the cross-link polystyrene microspheres (SiO2/polystyrene hydrophobic composite microspheres), on which the SiO2 rough structure was sucessfully designed via suspension polymerization along with sol-gel reaction in one step. Besides, effects of the oil phase composition, amount of the KH570 and the sol-gel reaction condition on the strength and hydrophobic properties of the SiO2/polystyrene hydrophobic composite microspheres were studied. The results show that the SiO2/polystyrene hydrophobic composite microspheres with durable hydrophobic properties, high strength and ultra-low density could be obtained when the toluene in the oil phase is discarded and the pH value of the system is tuned to 10-11 by ammonia-water at the 50°C reaction stage. The SiO2/polystyrene hydrophobic composite microsphere exhibits the apparent density about 0.9917 g∙cm−3, low crushing rate (2.53% under 69 MPa closure pressure), high initial static water contact angle (as high as 140.7°) and excellent heat resistance (the glass transition temperature and decomposition temperature are up to 160°C and 390°C, respectively). When refluxed in the chelate acid HD and FA that applied in Well A5 in Weizhou X Oil field for 30 days, the static water contact angles on the surface of the SiO2/polystyrene hydrophobic composite microspheres fluctuate only within ±10% and ±7%, respectively. The SiO2/polystyrene hydrophobic composite microsphere shows great potential in deep reservoir as a proppant, which is also suitable for the water control process as a packing material.
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Key words:
- SiO2 /
- polystyrene /
- composite microspheres /
- hydrophobicity /
- high strength
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图 1 第一恒温阶段水解,体系pH值为7~8 (a) 、9~10 (b) 和11~12 (c) 及第二 (d)、第三 (e) 和第四 (f) 恒温阶段水解,阶段体系pH值为10~11时制得的SiO2/聚苯乙烯复合微球的SEM图像、表面形貌和表面静态水接触角
Figure 1. SEM images, surface roughness and static water contact angles of SiO2/polystyrene composite microspheres prepared when hydrolyzed at the first insulation stage with pH value of 7-8 (a), 9-10 (b) and 11-12 (c), and that prepared when hydrolyzed at the second (d), third (e) and the fourth (f) insulation stage with pH value of 11-12
图 4 SiO2/聚苯乙烯疏水复合微球 (a) 和商售疏水覆膜陶粒 (b) 在涠州X油田A5井的螯合酸HD和螯合酸FA中回流30天过程中的表面接触角变化
Figure 4. Surface water contact angle changes of SiO2/polystyrene hydrophobic composite microspheres (a) and hydrophobic coated ceramics (b) during refluxed for 30 days in the chelate acid HD and FA that applied in Well A5 in Weizhou X Oil field
表 1 油相中甲苯用量不同时制得的聚苯乙烯微球的孔结构和其在55 MPa闭合压力下的破碎率
Table 1. Pore structures and crushing rates under 55 MPa closing pressure of polystyrene microspheres obtained with different toluene contents in oil phase
mDVB: mSt Vtoluene∶Vwater Total pore volume/(mL∙g−1) Surface area/(m2∙g) Crushing ratio under 55 MPa/% 5∶5 1∶3 1.363×10−2 54.022 18.7 1∶4 1.083×10−2 36.456 10.7 1∶5 3.185×10−3 3.388 3.0 0 2.418×10−3 1.743 2.5 1∶5 0 2.432×10−3 1.303 2.4 Notes: mDVB∶mSt—Mass ratio of divinylbenzene (DVB) to styrene (St); Vtoluene∶Vwater—Volume ratio of toluene to water. 表 2 经过不同pH值和在不同恒温阶段水解得到的SiO2/聚苯乙烯复合微球表面粗糙度及静态水接触角(质量比DVB∶St∶KH570=1∶5∶0.75)
Table 2. Surface roughness and static water contact angles on the surface of SiO2/polystyrene composite microspheres prepared when hydrolysis at different pH values and at different heat preservation stages (Mass ratio DVB∶St∶KH570=1∶5∶0.75)
No. pH value Hydrolysis stage Surface roughness Static contact angle/(°) 1 7-8 First ○ 51.5 2 9-10 First √ 126.1 3 10-11 First √√ 140.7 4 Second √ 123.9 5 Third 122.8 6 Fourth 86.6 Notes: DVB—Divinylbenzene; St—Styrene; KH570—γ-methacryloxypropyl-trimethoxy silane; ○—Smooth; √—Rough; √√—Rougher than that labeled as √. 表 3 SiO2/聚苯乙烯疏水复合微球和商售疏水覆膜陶粒在混合酸中处理30 min后的稳定性
Table 3. Stability of SiO2/polystyrene hydrophobic composite microspheres and commercially hydrophobic coated ceramsite when treated in mixed acid for 30 min
Sample Initial contact angle/(°) After treated in mixed acid for 30 min Contact angle/(°) Loss of contact angle/% Mass loss/wt% SiO2/polystyrene hydrophobic composite microspheres 140.7 128.1 8.96 0.80 Commercially hydrophobic coated ceramsite 133.5 100.9 24.42 2.03 -
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