| Ordered porous polymer films have attracted intense attention due to their wide range of potential applications in separation membranes,patterned templates,photonic crystal,sensors,superhydrophobic surfaces.Up to now,the methods for preparing ordered porous polymer films include track-etching,nano-micro processing and self-assembly,etc.Through the orderly arrangement of condensed water droplets as the template,ordered porous polymer films can be prepared,which is called breath figure method.The process is simple,easy to operate,environment friendly.The breath figure method has become an important method of polymer films preparation.With the deepening of the research,a wide variety of polymers has been proven as the film-forming materials,from the linear polymer expanding to hyperbranched polymer.In this paper,we for the first time to put forward using supramolecular star polymers to prepare ordered porous polymer films,which provides a new series of film-forming materials for breath figure.The research contents as follows:Firstly,we synthesized a class of well-defined structure of clusto supramolecular star polymers(abbreviated as CSPs).We chose to use the same structure of the polyoxometalate cluster [CoW12O40]6-,[SiW12O40]4-and [PW12O40]3-as the inorganic core with a charge of 6,4,3,respectively.Through electrostatic interaction,the cationic chain transfer agents which contain trithiocarbonate group modified on the surface of polyoxometalate cluster,and then polystyrene arms were in situ grafted through reversible addition-fragmentation chain transfer polymerization,obtaining three [CoW12O40]6--cored star polymers: CSP-1,CSP-2,CSP-3,whose graft arm number is 6 and graft polymerization degree is 13,21,54,respectively;getting a [SiW12O40]4--cored star polymer: CSP-4,whose graft arm is 4 and graft polymerization degree is 21;gaining a [PW12O40]3--cored star polymer: CSP-4,whose graft arm is 4 and graft polymerization degree is 21.The polymerization dispersity index of all above five CSPs are less than 1.05,and the molecular structures of the CSPs have been confirmed by NMR,MODI-TOF,IR,EA,and so on.Secondly,we studied the relationship between molecular structure of CSPs and their film-forming behavior.At first,we chose chloroform as solvent,and the CSP-2 was used as the reference sample to determine the conditions such as concentration and moist gas flow.We prepared five kinds of porous films of CSPs under the same concentration of 6 mg/mL and the same gas flow of 400 mL/min.We found that under the same conditions,five kinds of porous polymer films exhibited different pore size and regularity.The pore size of the films distributed from 260 nm to 700 nm,all in sub-micro scale.Furthermore,combining the viscosity and the amphiphilicity of CSPs,we systematically analyzed their film-forming behavior.It’s suggested that the supramolecular structure of CSPs which can rearrange at the interface of oil/water and stabilize small water droplets is the key to form ordered porous polymer films.Thirdly,we studied the CSP-assisted formation of other porous polymer films.Given that the characteristic of CSPs is easy to enrichment at the interface of oil/water,we use them as morphological modifiers blending with linear polystyrene,to improve the microporous regularity of polystyrene films.We blended 1.5 wt% of CSP-2,CSP-4,CSP-5 asmorphological modifiers with the commercial linear polystyrene,and prepared porous polymer films by the breath figure method.We found CSP-2 can successfully induce the polystyreneto form ordered porous films with the pore size of 1.7 μm.In summary,by using the CSPs as representative,we for the first time fabricated porous polymer films based on star supramolecular polymers by the breath figure method.And then,we revealed the relationship between the molecular structure and the film-forming behavior of CSPs;at the same time,we used them as morphological modifiers to improve the film-forming morphology of linear polystyrene.These results provide new materials for the preparation of ordered porous polymer films. |
