Ludmila Starannikova

Synthesis and gas permeation properties of novel spirobisindane-based polyimides of intrinsic microporosity

Three novel polyimides (PIM-PIs) with characteristics similar to a polymer of intrinsic microporosity (PIM) were prepared by the reactions of a novel spirobisindane-based dianhydride with appropriate aromatic diamines. A polymerisation procedure via in situ ester precursor formation provided PIM-PIs with very high molar masses. The gas permeation parameters (permeability (P), diffusion (D) and solubility (S) coefficients) were determined for these polymers. These PIM-PIs exhibit both high apparent surface areas and high gas permeability coefficients, greater than those of most polyimides studied so far and only slightly smaller than the permeability coefficients of the archetypal polymer of intrinsic microporosity, PIM-1. Treatment of the films with alcohols results in significant increases the P values, just as has been noted for PIM-1. This enhancement is caused by an increase of the diffusion coefficients, while the solubility coefficients are much less sensitive to this treatment. However, PIM-PIs are distinguished by extremely high gas solubility coefficients a property, which is characteristic to all PIMs.

Membrane air separation for intensification of coal gasification process

Abstract High-ash and other low-quality coals are available in huge quantities in Russia and in other East European countries. Similar solid fuels can also be obtained as by-product of the enrichment process of coal. The aim of this work is the analysis of the possibility to use such low-quality coals as alternative energy sources in fluidised bed gasification process. In order to intensify gasification process in conditions where possible ash melting is avoided, it is proposed to use oxygen-enriched air (OEA) instead of air as a blow and gasification agent. The supply of OEA as fluidisation medium can be beneficial in other respects: it allows to burn at least a part of fly ash before they leave the furnace, thus improving energy efficiency and ecological impacts of the process. In this paper, the first successful example of combination of membrane air separation and coal gasification process is given. This paper summarises the performance of coal gasification in the presence of different oxygen/nitrogen mixtures as a blow for processing of low-quality (high moisture content) coal. The optimal content of O 2 in the blow is in the range 27–33% v/v. The heating value of synthesis gas obtained in optimal conditions was in the range 3.5–4.7 MJ/m 3 (STP). In second part of the paper, the performance of several membranes available for cheap and efficient air separation is analysed and, after comparing them, recommendations on appropriate selection of membrane type and module needed are given.

Radiation-induced crosslinking of polyvinyltrimethylsilane in the presence of ethylene glycol dimethacrylate and allyl methacrylate

Abstract Radiation-induced crosslinking of homogeneous glassy polyvinyltrimethylsilane was carried out either by the γ -irradiation of the polymeric films containing 3–20 wt% of ethylene glycol dimethacrylate or by the radiation-induced grafting of allyl methacrylate from vapour phase onto films made of pure polymer. The dependence of grafting value on the absorbed γ -irradiation dose and film thickness was investigated. The modified films were analyzed for the sol/gel content and the dependence of gel fraction yield of crosslinked polymer on absorbed dose, concentration of the crosslinking agents and film thickness. The radiation-chemical yields of crosslinking and degradation as well as gelation doses were calculated. The permeability of oxygen and nitrogen through the crosslinked films was determined.

New composites based on poly(3-trimethylsilyltricyclononene-7) and organic nature fillers (calixarenes & cyclodextrins)

Herein we describe new materials for membrane gas separation process with improved selectivities towards different pairs of gases. Organic nature fillers (modified calix[4]arenes, calix[8]arenes and modified α-, β-, γ-cyclodextrins) were used as additives to poly(trimethylsilyltricyclononene-7) (PTCNSi1)in order to study correlations between structure of the filling agent and gas transport parameters of the composite membranes. It was shown a positive influence of calixarenes and cyclodextrins as additives on permselectivity of the membranes. For instance, selectivity towards H2/CH4 gas pair increased almost in 2.4 times when calix[4]arene with Et- and tert-Bu- group was introduced into polymeric matrix. Detailed study of the PTCNSi1 adsorbtion/desortion data is presented. The obtained composites were characterized by TEM, WAXD, PALS and BET analysis.

Janus tricyclononene polymers bearing tri(n-alkoxy)silyl side groups for membrane gas separation

A series of polymers of a new type, which contain rigid polymer main chains (glassy nature) and long flexible side substituents (rubbery nature), were prepared from norbornene derivatives with (AlkO)3Si-groups of a different length (Alk = Me, Et, n-Pr, n-Bu) as promising materials for membrane separation of gaseous hydrocarbons. The 1st generation Grubbs complex and Pd–N-heterocyclic carbene complex in combination with Na+[(3,5-(CF3)2C6H3)4B]− and PCy3 were used as catalysts of metathesis and addition polymerization in the synthesis of high-molecular weight polymers (Mw ≤ 1.1 × 106) with good or high yields (up to 99%). The prepared addition polymers were glassy, while the glass transition temperature of metathesis polymers depended on the length of the alkyl-group in (AlkO)3Si-substituents and it varied in the range of −44 to 61 °C. The dramatic tuning of polymer gas-transport properties was demonstrated by the change of the polymer main chain structure and the length of tri(n-alkoxy)silyl side groups. For example, we have succeeded for the first time in obtaining metathesis polynorbornenes, which turned out to be more permeable than their addition isomers. Not being large free volume polymers, all studied metathesis and addition polytricyclononenes exhibited solubility controlled permeation of hydrocarbons (P(n-C4H10) up to 8100 barrer) and high C4/C1 selectivity (22–49).

New Membrane Materials Via Catalytic Polymerization of Bis(Trimethylsilyl)-Substituted Norbornene Type Monomers

In this work we summarize our results of investigation on ring-opening metathesis (ROMP) and addition polymerization (AP) of a range of norbornene, norbornadiene and tricyclononene monomers containing two Me3Sisubstituents. The tested monomers exhibited different reactivity in ROMP and AP. The new polymers obtained demonstrated high gas permeability and allowed defining some correlations between features of their chemical structure and gas separation characteristics.