Synthesis and applications of polybenzoxazine membranes

Abstract

The present work focuses on synthesizing polybenzoxazine via a facile "quasi-solventless" method by using bisphenol-A, formaldehyde and diamine to fabricage as membrane for spearation application. Four different diamines, viz. hexa-methylenediamine (hda), tetraethylenepentamine (tepa), ethylenediamine (eda), and triethylenetetramine (teta), were used to prepare polybenzoxazine membranes, denoted as poly(BA-had), poly(BA-tepa, poly(BA-eda), and poly(BA-teta), respectively, for pervaporation testing. It was found that both poly(BA-hda) and poly(BA-eda) showed a very good performance with separation factor of higher than 10,000 and permeation flus of higher than 1.00 kg/m2h at 70C using 10:90 ethanol:water feedng mixture and 200 um membrane thickness. However, the poly(BA-eda) membrane provided higher permeation flux and separation factor with increasing ethanol concentration. Moreover, the poly(BA-hda) was also used to mix with ZSM-5 to prepare a mixed matrix membrane (MMM) for CO2/CH4 gas separation, and the results show that 5 wt% of ZSM-5 loading showed great CO2 and CH4 permeability and selectivity when comparing with those with other ZSM-5loading content. Among the synthesized membranes, the poly (BA-hda) vave the best separation performance, thus, its property details, viz. molecular weight, radius of gyration and hydrodynamic radius, were studied using static and dynamic light scattering as function of time. The swelling and sorption behaviours of the polybenzoxazine membranes were also studied.