Synthesis and Study of Gas Transport Properties of Polymers Based on Macroinitiators and 2,4-Toluene Diisocyanate

Abstract

Nowadays, block copolymers hold great promise for the design of novel membranes to be applied for the membrane gas separation. In this regard, microporous block copolymers based on a macroinitiator with an anionic nature, such as potassium-substituted block copolymers of propylene oxide and ethylene oxide (PPEG) and 2,4-toluene diisocyanate (TDI), were obtained and investigated as effective gas separation membranes. The key element of the macromolecular structure that determines the supramolecular organization of the studied polymers is the coplanar blocks of polyisocyanates with an acetal nature (O-polyisocyanate). In the present research, the influence of the content of peripheral polyoxyethylene (POE) blocks in PPEG on the supramolecular structure processes and gas transport characteristics of the obtained polymers based on PPEG and TDI was investigated. According to the study of polymers if the POE block content is 15 wt %, the polyoxypropylene segments are located in the internal cavity of voids formed by O-polyisocyanate blocks. When the POE block content is 30 wt %, the flexible chain component forms its own microphase outside the segregation zone of the rigid O-polyisocyanate blocks. The permeability for polar molecules, such as ammonia or hydrogen sulfide, significantly exceeds the permeability values obtained for non-polar molecules He, N2 and СН4. A relatively high permeability is also observed for carbon dioxide. At the same time, the content of POE blocks has a small effect on the permeability for all studied gases. The diffusion coefficient increases with an increase in the POE block content in PPEG for all studied gases.

Experimental Evaluation of the Efficiency of Membrane Cascades Type of “Continuous Membrane Column” in the Carbon Dioxide Capture Applications

“…As a preliminary study, the gas transport characteristics were determined and the ideal and apparent (effective) selectivities of the MDK-3 membrane and the symmetric membrane based on quaternized chitosan were calculated. The permeability of individual gases was measured by the Daynes-Barrer time lag method [36,37] detailed in previous papers of the authors [38][39][40]. To determine the permeability of the components of the gas mixture and calculate the effective selectivity of the MDK-3 membrane, the gas chromatographic method was used as described in detail in [41,42].…”

Amphiphilic Poly(dimethylsiloxane-ethylene-propylene oxide)-polyisocyanurate Cross-Linked Block Copolymers in a Membrane Gas Separation

“…As a result, the supramolecular structure of such polymers acquires a cellular character. In connection with the results obtained earlier in the work [ 45 ], Table 2 shows the values of the permeability coefficient for a number of gases using a polymer with a cellular supramolecular structure obtained with [PPEG]:[TDI] = 1:15 in the presence of acidic cocatalysts as a membrane. Table 3 shows the corresponding ideal selectivity values.…”

“…According to the work [ 45 ], the reaction conditions have a significant effect on the mechanism of TDI polyaddition initiated by the terminal potassium alcoholate groups of PPEG. Therefore, when carrying out the reaction at relatively low temperatures and in the presence of acidic cocatalysts, isocyanate groups of the para-position in the TDI are opened via the carbonyl component, followed by the formation of coplanar acetal-type polyisocyanate blocks.…”

“…It was found that Si–O–C bonds, being an integral part of the resulting polymer matrix, are not subjected to hydrolytic effects. Preliminary studies have shown that this approach is promising for a directed influence on the supramolecular organization and the design of polymeric gas separation membranes [ 43 , 44 , 45 , 46 ].…”

Synthesis and characterization of amphiphilic branched silica derivatives associated with oligomeric medium

“…These polymers are of interest due to their high gas transport characteristics. [48][49][50][51][52][53][54] The specic characteristics of theirs supramolecular structure is polyisocyanate blocks of acetal nature (O-polyisocyanates) as a component with a rigid chain. A scheme of polymers synthesis by the reaction of Microporous polymers modied with ASiP was investigated using FTIR spectroscopy.…”