取心工具用大尺寸疏水吸油海绵的制备与吸油性能研究

海绵取心工具（取心衬筒）中一种关键材料是高吸油海绵，为了满足钻井取心的使用需求，需要制备大尺寸、超疏水的吸油海绵。利用多巴胺（DA）氧化自聚（以NaIO₄为氧化剂）以及聚多巴胺（PDA）与疏水剂（十八胺，ODA）的反应，采用一步和两步浸涂法对小尺寸（30 mm×30 mm×10 mm）和大尺寸（910 mm×400 mm×10 mm）商用三聚氰胺海绵进行疏水改性；利用扫描电子显微镜（SEM）观察改性海绵的表面形貌，并测定其水接触角和吸油性能。结果表明：改性海绵表面形成了PDA粒子，两步法所得改性海绵的表面粒子细密、均匀；增大DA的质量浓度和提高氧化剂含量，海绵表面PDA粒子增多。确定了海绵改性的最优条件：DA质量浓度为4~6 mg/mL，DA与NaIO₄的质量比为1：1，海绵在ODA溶液中的浸泡时间为2~4 h。在小尺寸样品研究结果的基础上，将大尺寸海绵在DA溶液中浸泡1 min，在空气中放置2 h，然后与ODA溶液反应4 h进行改性，所得大尺寸改性海绵的表面水接触角为152.6°，10 s时吸油量达90 g/g，并且多次吸油、析油后仍保持较高的吸油量和解析率，可以满足取心衬筒的使用要求。

Preparation and oil absorption performance of large-size hydrophobic oil-absorbing sponges for coring tools

High oil absorption sponges are a key component of sponge coring tools (coring liner). In order to meet the needs of drilling coring, it is necessary to prepare large size and superhydrophobic oil absorption sponge. Hydrophobic modification of commercial melamine sponges with small size (30 mm×30 mm×10 mm) and large size (910 mm×400 mm×10 mm) was carried out by one-step and two-step dip-coating methods using the oxidation self-polymerization of dopamine (DA) (with NaIO₄ as oxidant) and reaction of polydopamine (PDA) with hydrophobic agent (octadecylamine, ODA). The surface morphology of the modified sponges was observed by scanning electron microscopy (SEM), and the water contact angle and oil absorption performance were measured. The results show that PDA particles are formed on the surface of the modified sponges, and the particles on the modified sponge obtained by two-step method are fine and uniform. With the increase of DA concentration and oxidant content, more PDA particles appeared on the sponge surface. The optimum conditions for modification were determined as follows:DA 4-6 mg/mL, DA to NaIO₄ was 1:1 (wt.), and 2-4 h for sponge soaking in ODA solution. Based on the results obtained from small size samples, large-size sponges were soaked in DA solution for 1 min, placed in air for 2 h, and then reacted with ODA for 4 h. The surface water contact angle of the resulting large-size modified sponge was 152.6°, and the oil absorption reached 90 g/g at 10 s. Moreover, the oil absorption and desorption rate remained high after multiple cycles of oil absorption and desorption, showing that the material meets the requirements for a coring liner.