Vinyl Ester Oligomer Crosslinked Porous Polymers Prepared via Surfactant-Free High Internal Phase Emulsions

Yun Zhu,Jianding Chen,Chun Pu Hu,Ye Hua,Shengmiao Zhang

doi:10.1155/2012/307496

Yun Zhu, Jianding Chen + Show 3 more

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https://doi.org/10.1155/2012/307496

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Abstract

Using vinyl ester resin (VER) containing styrene (or methyl methacrylate) and vinyl ester oligomer (VEO) as external phase, Pickering high internal phase emulsions (Pickering HIPEs) having internal phase volume fraction of up to 95 vol% were prepared with copolymer particles as sole stabilizer. Polymerizing the external phase of these Pickering HIPEs led to porous polymers (poly-Pickering-HIPEs). Compared to the polystyrene- (PS-) based poly-Pickering-HIPEs which were prepared with mixture of styrene and divinylbenzene (DVB) as crosslinker, the poly-Pickering-HIPEs herein showed much higher elastic modulus and toughness. The elastic modulus of these poly-Pickering-HIPEs increased with increasing the VEO concentration in the external phase, while it decreased with increasing internal phase volume fraction. Increasing VEO concentration in the external phase also resulted in a decrease in the average void diameter as well as a narrow void diameter distribution of the resulting poly-Pickering-HIPEs. In addition, there were many small pores in the voids surface caused by the volume contraction of VER during the polymerization, which suggests a new method to fabricate porous polymers having a well-defined hierarchical pore structure.

Highlights

High internal phase emulsions (HIPEs) are defined as emulsions, in which the internal phase occupies higher than 74.05 vol% of the emulsion
The E (12.2 MPa) of poly-Pickering-HIPE SV10-90 was much higher than that (6.4 MPa) of the poly-Pickering-HIPE SD10-90 and was much higher than the E (3.0 MPa) of the PS-based polyHIPE prepared with the HIPE having internal phase volume fraction of 89% [27]
Compared to the poly-Pickering-HIPEs with DVB as crosslinker, vinyl ester oligomer (VEO) as crosslinker is conducive to the enhancement of both E and toughness of the poly-PickeringHIPEs

Summary

Introduction

High internal phase emulsions (HIPEs) are defined as emulsions, in which the internal phase occupies higher than 74.05 vol% of the emulsion. Increasing interests are attracted to use the emulsions as templates for the production of highly porous polymers (known as polyHIPEs) [3,4,5,6,7,8,9,10,11,12,13,14,15,16] Such materials are prepared by polymerizing the thin films that surround the droplets of the HIPEs if the continuous phase contains one or more monomeric species that are polymerizable. To eliminate the surfactants used in HIPEs, the authors, and other groups, have prepared HIPEs using organic or inorganic particles as stabilizer [3,4,5,6,7,8,9, 16] Such emulsions are known as Pickering HIPEs. And the porous polymers based on this type of emulsions are known as poly-PickeringHIPEs. By far, the most widely studied monomer used in poly-Pickering-HIPEs is styrene (St). Styrene is a reactive diluent, and VEO serves as a crosslinking agent for

H O C C CH2

Experimental Section

Results and Discussion

Conclusions