Relationships between structure, permeability and glass transition temperature of oligodimethylsiloxanyl substituted polymers

ABSTRACT:The permeation of oxygen and nitrogen through the membranes of poly-(N-n-alkylmaleimide )s including poly(N-n-butylmaleimide) [poly(nBMI)] and poly(N-dodecylmaleimide) [poly(DodMI)] was investigated. These membranes from polymaleimides have been revealed to have high permeability coefficients even under their glass transition temperatures on account of facile permeation through the fused alkyl chain in the side group. The apparent diffusion coefficient was determined to be greater than 10-6 cm 2 s-1 for poly(DodMI), and the facile diffusion in the polymer was discussed.KEY WORDS N-n-Alkylmaleimide / Poly(substituted methylene) / Glass Transition Temperature / Gas Permeability / Permeability Coefficient / Diffusion Coefficient / Mobility of Side Chain / Membrane / number of the side chain increases. Gas transport properties of polyimide films which have a variety of chemical structures have been reported on account of a high glass transition temperature and excellent thermal stability. 1 -10 We reported on the radical polymerization of N-alkyl-substituted maleimides and N-(alkyl-substituted phenyl)maleimides bearing various alkyl groups, and on the excellent thermal stability of the resulting polymers. 11 In the previous paper, 12 • 13 we also reported that radical polymerization of N-nalkylmaleimides (RMI) with various kinds of n-alkyl groups as an N-substituent proceeded easily to give high molecular weight polymers in high yields. The polymer membranes prepared by casting show high permeability to oxygen and nitrogen, i.e., permeability coefficients (P 02 and PN) are in the range of 10-9 to 10-8 cm 3 (STP)cmcm-2 s-1 cmHg-1 , although they are glassy polymers with high glass transition temperatures. It has been revealed that permeability depends on the length of the alkyl side chain, i.e., P increases as the carbon In this study, gas permeation through the polymer membranes of poly(N-n-butylmaleimide) [poly(nBMI), n=4] and poly(N-dodecylmaleimide) [poly(DodMI), n= 12] as well as other poly(RMl)s (Scheme I) was investigated and the permeation mechanism is discussed.

mentioning

confidence: 73%

Gas Permeation through Poly(N-n-alkylmaleimide) Membranes

Oki

Otsu

1991

“…Evaluation of dynamic mobility of local segments by solid state NMR will make more detailed discussion possible. 7 When we compare the effects of siloxane linkage in main-chain and side-chain, increase in permeability and diffusion coefficients is higher when they are introduced into sidechain. This also reflects the higher mobility of oligosiloxane in side-chain than in main-chain.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Gas Permeability of Aromatic Polyamide and Polyimide Having Oligodimethylsiloxane in Main-Chain or in Side-Chain

Kawakami

Abe

1992

Self Cite

ABSTRACT:Aromatic polyamides and polyimide having oligodimethylsiloxane of defined length (1-4 Si atoms) in main-chain or in side-chain were synthesized by polycondensation of bis(4-aminophenyl)-functionalized oligodimethylsiloxanes with acid dichloride or pyromellitic dianhydride. Glass transition temperature and gas permeability of the polymers were markedly influenced by the introduction of oligodimethylsiloxane components into the polymer. The effects was more notable in polymers having oligodimethylsiloxane as side-chains.KEY WORDS Oligodimethylsiloxane I Polyamide I Polyimide I Glass Transition Temperature I Gas Permeation I During the last decade, remarkable progress has been made in the technology of gas separation by selective permeation through polymer membranes. However, only few significant studies on the structure-permeability relationships have been published until now, and insufficient understanding of the relationships between the chemical structure of polymers and their gas permeability makes the progress slow, hence new materials for membranes are developed only on a trial-anderror basis. For further progress, creation of new polymers which exhibit both a high selectivity for specific gases and a high intrinsic permeability based on molecular design of the polymer is essential. 1 We reported that introduction of oligodimethylsiloxane as substituents into polymer structure is an excellent method to develop selectively oxygen permeable membrane matet To whom correspondence should be addressed. rials of well-balanced property between permeability, selectivity in permeation and mechanical strength of the membrane. In order to clarify the role of siloxane linkage in permeation, and to establish the relationships between structure and permeability, glass transition temperature, several polymers having oligodimethylsiloxane side-chains have been synthesized, and their properties were estimated. 2 -7

“…It is already reported that the effect oflowering the glass transition temperature of polystyrene by the branched (p-oligodimethylsiloxane)-substituent is smaller than that by linear substituent. 43 Although direct comparison could not be made, the transition enthalpy seems smaller in case of branched substituent compared with the linear substituent (3.3 mJmg-1 for POX-CN-S8).…”

Section: Thermal Analysismentioning

confidence: 99%

Synthesis of Liquid Crystalline Polyoxetanes Bearing Cyanobiphenyl Mesogen and Siloxane-Containing Substituent in the Repeating Unit

Kawakami

Suzuki

Kato

et al. 1996

Self Cite

ABSTRACT:Cyanobiphenyl mesogen-containing oxetanes functionalized by a second siloxane-containing substituent on the same carbon atom of the ring were synthesized. Polymers were obtained by cationic polymerization with BF 3 · OEt 2 or Et3O + BF 4 as an initiator. The poiymers showed smectic liquid crystalline phase. Introduction of siloxane linkage in the second substituent kept the glass transition temperatures of the polymer almost constant irrespective of the difference of the spacer length. The clearing temperature became higher with the increase in the length of the spacer group connecting the mesogenic group to the main chain. By these two effects on the transition temperatures, the temperature range of the liquid crystalline state became wider with the increase in the length of the spacer group.KEY WORDS Oxetane / Cyanobiphenyl / Siloxane Linkage/ Cationic Polymerization/ Glass Transition Temperature / Liquid Crystalline Polymer / Smectic Phase / Much attention has been paid recently to liquid crystalline polymers, especially to side-chain type, because of their potential application for electronic devices. Poly(siloxane)s, poly(acrylate)s, and poly(methacrylate)s are common main chain components of such liquid crystalline polymers. 1 -4 There are some new examples in which hetero-atom containing main chain like poly(phosphazene ), poly(aziridine ), polyether, or poly(isocyanate) are used. 5 -24 We have been interested in the relationship between the structures of main chain, spacer, and mesogenic group and the liquid crystalline phase exhibited by the polymer, and reported examples of liquid crystalline poly( oxetane)s 20 -22 and polydienes. 25 -2 7 In the reports, 2 5 -2 7 we showed the effective role of the siloxane linkage as a constituent of the spacer. Effectiveness of the introduction of a siloxane linkage in the spacer in exhibiting well-organized liquid crystalline phase was also pointed out. 28 -30 Meanwhile considerable interests have been paid to the effect of the introduction of a second monomer component into a liquid crystalline polymers by random copolymerization 31 -35 or block copolymerization. 36 However, by these methods, second component can be introduced only on the basis of the monomer reactivity ratio or as a microphase-separated segments, accordingly, it is difficult to introduce a second specific functional group at the specific position to the mesogenic group.We were interested in the effects of siloxane linkage as the second substituents, and synthesized oxetane monomers having a siloxane-containing substituent along with the mesogenic group on the same carbon atom in the molecule in order to introduce these groups at the specific position to the mesogenic group in the polymer. In this article, we would like to report on the synthesis of the monomers, polymerization and the effect of the second component on the liquid crystalline behavior of the formed polymers.1 To whom correspondence should be addressed. EXPERIMENT AL 1 H and 13 C NMR spectra were obtained on a Varian ...