Study On Pickering Emulsion Stabilized By Terpineol Modified Graphene Oxide

The Pickering emulsion polymerization method of graphene is a custom-made polymer/graphene composite material polymerization method.In order to obtain a granular polymerization product,the emulsion droplets must remain stable during the polymerization process.Therefore,graphene can automatically adsorb on the oil-water phase interface and form a stable interface film that is not destroyed during the polymerization process,which is a key.GO,as the emerging Pickering emulsion stabilizer,is too hydrophilic,easy to disperse in water and not easy to distribute on the phase interface,the formed interface film is not strong enough,and the emulsion stability is poor.Therefore,this paper uses terpineol to modify two graphene oxides(GO and SGO)to improve their emulsification ability.The optimal modification conditions of terpineol and the emulsification adaptability of terpineol modified products TGO and TSGO under different conditions(p H,oil phase,ionic strength)were studied.A polystyrene/graphene composite material with a hollow structure is prepared through the styrene Pickering emulsion of the four graphene derivatives.The specific research content is as follows:(1)Graphene oxide(SGO)is prepared by increasing the amount of potassium permanganate in the Hummers method for preparing graphene oxide,reducing its size and increasing its degree of oxidation,and improving the emulsification ability of graphene oxide.Studies have shown that,compared with graphene oxide(GO)prepared by the conventional Hummers method,the amount of potassium permanganate will not change the group and crystal surface structure of the product,but it will affect the size of the product,the number of graphene stacks and the degree of oxidation.The more potassium permanganate is used,the smaller the size of graphene oxide,the smaller the number of layers,the higher the degree of oxidation,and the better the emulsification ability of graphene oxide.(2)Improve the emulsification ability of graphene oxide by modifying terpineol.Studies have shown that terpineol and graphene oxide can undergo an esterification reaction.After esterification,the defect degree and oxidation degree of graphene oxide(TGO,TSGO)are reduced.These changes enhance the emulsification ability of graphene oxide.The best modification conditions are p H=1,terpineol dosage 1.8 times the mass of graphene oxide,and reaction at 80 ℃ for 40 min.At this time,the water contact angle of TGO and TSGO is the largest,the surface hydrophilic and lipophilic properties are suitable,and the emulsifying ability is the strongest.(3)The emulsification adaptability of TGO and TSGO in different environments was studied.It is found that TGO and TSGO can stabilize emulsions at different p H,Na Cl is 1-10 times the mass of GO,aromatic hydrocarbons,alicyclic hydrocarbons,and aliphatic hydrocarbons.TSGO can also stabilize ester oils that cannot be stabilized by TGO.Phase emulsion.Both have the strongest emulsification ability in the oil phase environment with p H=8-11,no Na Cl added,and strong interaction with graphene oxide,and the emulsification ability of TSGO is stronger than TGO under the same environment.(4)The styrene/water emulsion stability of TGO and TSGO was studied,and it was found that TGO styrene/water emulsion has a long-term static stability of more than 30 days at room temperature.At 65 ℃,these two phenomena will be aggravated and the stability of the emulsion will decrease.At room temperature,TSGO styrene/water emulsion has a long-term static stability of more than 60 days and the droplet size remains unchanged.At 65 ℃,TSGO styrene/water emulsion can maintain the same droplet size for 7 h.This property is the prerequisite for the preparation of granular polymer products by polymerization reaction.(5)Analyze the morphology of emulsion polymerization products of GO,TGO,SGO and TSGO.The emulsifying and stabilizing abilities of the four Pickering emulsion stabilizers of GO,TGO,SGO and TSGO are successively improved.Depending on the strength of the interface film,the polymer products obtained after their styrene Pickering emulsion polymerization can be divided into two states: solid products and PS emulsions.The solid products mainly have three types of morphological structures: irregular large blocks,millimeter-level spherical particles and eggshell fragments,and sub-millimeterlevel powdered microspheres.The formation and proportion of these three types of morphological polymers have a great relationship with the interface film strength of Pickering emulsion.The stronger the interfacial film strength,the more stable the emulsion system,and the higher the proportion of sub-millimeter powdery microspheres similar to the emulsion size in the product.(6)Further analyze the influencing factors of the morphology of the polymerized product.The ratio of the total surface area of the stabilizer to the total surface area of the oil droplets is used as an effective index for investigating the strength of the interface film of Pickering emulsion.Reduce the size and number of layers of graphene oxide to increase its surface area,adjust the hydrophilic-lipophilic balance of graphene oxide through terpineol modification,and increase the proportion of graphene oxide in styrene can increase the ratio of the total surface area of the stabilizer to the total surface area of the oil droplets,and they are both favorable factors for improving the emulsification ability of graphene oxide and the strength of the interfacial film.