HBPI-silica hybrid membranes

The HBPI-silica hybrid membranes were prepared by thermal imidization and sol-gel reaction with two kinds of alkoxysilanes, TMOS and/or MTMS. Appropriate amounts of TMOS and/or MTMS and ion exchange water were added in the DMAc solution of the hyperbranched polyamic acids. For TMOS/MTMS combined system, TMOS and MTMS were added to achieve equivalent weight fraction of silica components arising from TMOS and MTMS. The mixed solutions were stirred for 24h and cast on PET films and... 

Figure 8.3 FT-IR spectra of 6FDA-TAPOB HBPI-silica hybrid membranes (silica...

Physical and Gas Transport Properties 149 Table 8.1 Physical properties of HBPI-silica hybrid membranes... 

J2 Gas Transport Properties of HBPI-Silica Hybrid Membranes... 

Table 8.2 Permeability coefficients and ideal selectivity of HBPI-silica hybrid membranes at 76 cmHg and 25 °C...

Figure 8.5 CO2 permeability (a), diffusion (b) and solubility (c) coefficients of 6FDA-TAPOB HBPI-silica hybrid membranes plotted against silica content...

Figure 8.7 Ideal CO2/CH4 selectivity (a(C02/CH4)) of HBPI-silica hybrid membranes plotted against CO2 permeability coefficient...

In this paper, physical and gas transport properties of HBPIs synthesized with various dianhydride monomers and their silica hybrid membranes prepared by sol-gel reaction with two kinds of alkoxysilanes, TMOS and methyltrimethoxysilane (MTMS), individually or simultaneously, are discussed. The methyl group of MTMS will prevent the formation of robust three-dimensional Si-O-Si network in the hybrid membranes. It is expected that the loose Si-O-Si network formed from MTMS induces unique physical and gas transport properties of the hybrid membranes. 

Optical transmittances of the hybrid membranes are shown in Table 8.1. The hybrid membranes have high homogeneity and silica particles are finely dispersed in the HBPIs... 

Coefficients of thermal expansion (CTEs) from 100 to 150°C of the hybrid membranes are listed in Table 8.1. The CTE of the TMOS system greatly decreases with increasing silica content, indicating the enhancement of thermal mechanical stability of the HBPIs by the formation of robust three-dimensional Si-O-Si network. In contrast, the CTE of... 

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