Study On Preparation And Properties Of Polystyrene-based And Poly (Melamine Formaldehyde)-based Porous Materials From HIPE Template Method

The porous polymers with well-defined pore structure and high specific surface area can be easily prepared by high internal emulsion (HIPE) template method. The porous polymers prepared with HIPE template were defined as polyHIPE. These porous polymeric materials can be widely applied in many fields, such as adsorption, biomedical medicine, catalyst support, preparation of inorganic porous materials, and so on. However, this method has some limitations. Generally, the mechanical properties of the resultant porous polymers are poor and poly(melamine formaldehyde)-based porous material cannot be easily synthesized by this method. Additionally, superhydrophobic porous materials have gained great attentions for their capability of selective adsorption of oils while completely repelling water. Unfortunately, most of the synthetic methods for superhydrophobic porous materials have problems such as complicated/lengthy processes, high cost for reagents/equipment and usage of toxic agents.In order to solve these problems, firstly, we combined RAFT polymerization and Pickering HIPE to obtain porous polystyrene-based polyHIPE (PS-polyHIPE) with good mechanical properties. Secondly, we combined RAFT polymerization and supramolecular interaction, to prepare strong PS-polyHIPE with high porosity. Thirdly, we introduced Pickering HIPE template into the preparation of porous poly(melamine formaldehyde)-based materials. Furthermore, we prepared superhydrophobic melamine sponge by one pot method and researched their application for oil/water separation. The main results are as follows.(1) We have prepared nine PS-polyHIPE samples under different kinds of initiators and emulsifier content condition. The samples were characterized with SEM, mercury intrusion and universal material tester. The results indicated that the type of initiators and content of emulsifier have significant effect on the morphology and mechanical property of resultant PS-polyHIPEs. By using V-20 as an initiator and 8vol% emulsifier, resultant polyHIPE exhibited the highest young’s modulus and the highest yield strength. Based on the results, we have proposed the possible mechanism about the influence of initiator type and emulsifier content on the mechanical properties.(2) Four PS-polyHIPE samples containing UPy (2-ureido-4-[H]-pyrimidinone) group 0,0.04,0.10 and 0.16 mmol/g respectively, were prepared by RAFT polymerization. The samples were characterized by FT-IR, element analysis, SEM, mercury intrusion, and universal material tester. It was found that when the UPy group content reached 0.16 mmol/g, the resultant PS-polyHIPE had the highest Yang’s modulus while its porosity was 91.88%. The Yang’s modulus increased by 50% comparing with the PS-polyHIPE without UPy group. The result demonstrated that the reinforcement of UPy group for the resultant PS-polyHIPE is not on the cost of sacrifice of porosity of PS-polyHIPE.(3) We introduced RAFT polymerization into SiO2 nanoparticles stabilized HIPE, polymerized the HIPE and obtained nine PS-polyHIPE samples. The samples were characterized with SEM, EDS, mercury intrusion and universal material tester. The results indicated that the content of Span80, silica nanoparticles and RAFT reagent have significant effect on the morphology and mechanical properties of the resultant porous polymeric materials. By using 5vol% of Span80,3wt% of silica nanoparticles as stabilizers and 1:1 of RAFT reagent/initiator ratio, the resultant PS-polyHIPE had the highest young’s modulus and good toughness.(4) By using lignin particles as stabilizer for Pickering HIPEs, we have prepared seven poly(melamine formaldehyde)-based porous materials (PMF-polyHIPE) with different lignin content and different internal phase ratio. The samples were characterized with SEM, mercury intrusion and universal material tester. It was found that open-cell porous PMF-polyHIPE can be obtained at low content (0.05wt%). Moreover, at relative low content of lignin (0.09wt%), when the volume ratio of internal phase is over 80%, open-cell porous PMF-polyHIPE also can be obtained. Based on the obtained results, we proposed the primary mechanism for the formation of windows.(5) By using melamine sponge as raw material, we prepared seven melamine-based superhydrophobic porous materials (sMS) samples under different temperatures and different dopamine hydrochloride content condition by one pot method at room temperature. It was found that the resultant sMS was superhydrophobic. The sMS can separate oil from water effectively. When the dopamine hydrochloride content is 3.0mg/mL, the resultant sMS was coated by a hydrophobic layer which is composed of polydopamine particles with size range from 100nm to 800nm. The sMS showed a contact angle as high as 165°. The oils can be adsorbed from the mixture of oil and water selectively by direct immersion mode. Moreover, the sMS exhibited good environmental stability and high adsorption capability. The sMS also showed excellent recyclability with sorption capacity retention near 100% after 16 cycles of sorption-squeezing for n-hexane.