Synthesis Of Trimethylsilyl Methylcellulose And Oxygen-enriching Properties Of Its Composite Membranes

Cellulose and its derivatives, which used as the membrane separation m aterials, are a type of abundance and environment friendly nature polymers, a nd have been Trimethylsilyl methylcellulose(TMS- MC) with different degrees h ave been synthesized by using methylcellulose as a material and hexamethyld isilazane as a reactant and its chemical structures are characterized by using FT-IR and ¹H-NMR methods. TMS-MC membrane and the composite membr ane of TMS- MC / N, N'- disalicylideneethylenediamine cobalt (Co(salen)) me mbrane are obtained by casting their solution. Besides, silicon rubber(PDMS) had attracted people's much attention due to its high permeability coefficient f or oxygen(Po₂=600Barrer), However, PDMS membrane has lower factor(αo₂/N₂ = 2). Consaquencely, the TMS-MC/PDMS membranes are prepared in the sa me way in order to improve αo₂/N₂. Furthermore, cobalt (II) is introduced into the composite membrane. And the effects of vinylacetic acid content, pressur e difference and testing temperature on P02 and αo₂/N₂ are investigated.The results show: â‘  TMS- MC has better solution property. The TMS- MC membrane can be prepared easily at room temperature. Compared with MC membrane, P02 and αo₂/N₂ of the membrane has improved simultaneously. For example, αo₂/N₂ is 5.42 at under pressure difference of 0.5MPa and 20℃; Because of the addition of the Co(salen), Not only permeability coefficients for O₂ are increased obviously, but also the better selectivity factors for O₂ and N₂ are obtained simultaneously under low pressure difference, especially for the latter.â‘¡ TMS- MC are introduced into the crosslinking network structure of PDMS membranes. When the TMS- MC content is 5 wt%, Po₂ (437 Barrer) is decreased slightly, but αo₂/N₂ (3.7) is increased obviously; Under the condition of low pressure difference, Po₂ (581 Barrer) and αo₂/N₂ (4.27) are increased simulateneously due to the addition of vinylacetic acid cobalt.