Download or read book Molecular Engineering of Liquid Crystal Polymers by Living Polymerization 11 Synthesis and Characterization of Poly 911 994 Cyano 4 trans a Cyanostilbene oxy undecanyl Vinyl Ether written by V. Percec and published by . This book was released on 1991 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: A convenient method for the synthesis of 11-(4-cyano-4'-trans-alpha-cyanostilbene)oxyundecanyl vinyl ether (6) which is the first member of a new class of mesogenic monomers is described. The polymerization of 6 initiated with CF3SO3H/S(CH3)2 in methylene chloride at proceeds through a living cationic mechanism leading to polymers with controllable molecular weights and polydispersities narrower than 1.10. The mesomorphic behavior of both 6 and poly(6)s with various molecular weights was determined by using a combination of thermal optical polarized microscopy and differential scanning calorimetry. 6 is only crystalline. Poly(6)s with degrees of polymerization from 4 to 30 exhibit an enantiotropic smectic A mesophase and side chain crystallization.
Download or read book Molecular Engineering of Liquid Crystalline Polymers by Living Polymerization 20 Synthesis and Characterization of Binary Copolymers of 11 4 Cyano 4 biphenyl Oxy undecanyl Vinyl Ether with N Butyl Vinyl Ether and of 2 4 Cyano 4 biphenyl oxy ethyl Vinyl Ether with N Butyl Vinyl Ether written by and published by . This book was released on 1992 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Copolymerization represents the simplest synthetic technique which can be used to tailor make phase transitions of both main chain and side chain liquid crystalline polymers. Indeed, copolymerization was frequently employed to manipulate the phase transitions of side chain liquid crystalline polymers. However, most of the results reported in the literature can be considered only in a qualitative way, since there are only very few cases in which information about both copolymer composition and molecular weight are available. A general classification of side chain liquid crystalline copolymers was recently discussed in a review article. There are two main classes of side chain liquid crystalline copolymers. The first one refers to copolymers containing pairs of structural units with and without mesogenic units. The second class refers to copolymers based on pairs of structural units containing mesogenic units in each structural unit.
Download or read book Government Reports Annual Index written by and published by . This book was released on 1991 with total page 1188 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Molecular Engineering of Liquid Crystalline Polymers by Living Polymerization 22 Synthesis and Characterization of Binary Copolymers written by and published by . This book was released on 1992 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: The synthesis and characterization of poly(11-(4-cyano-4'-biphenyl) oxy)undecanyl vinyl ether-co-(2S,3S)-(+)-2-chloro-3-methylpentyl 4'-(8- vinyloxyoctyloxy)biphenyl-4-carboxylate)X/Y (poly(6-11)-co-(15-8)X/Y) (where X/Y represents the molar ratio of the two structural units) and poly(2S,3S)-(+)-2- chloro-3-methylpentyl 4'-(8-vinyloxyoctyloxy)biphenyl-4-carboxylate-co-3((4- cyano-4'-biphenyl)oxy)propyl vinyl ether)X/Y (poly(15-8)-co-(6-3))X/Y) with degree of polymerization of about 20 and molecular weight distribution of about 1.1 are described. The mesomorphic behavior of all copolymers determined from both first, second and subsequent differential scanning calorimetric (DSC) scans was discussed as a function of composition. As determined from the second DSC scans, poly(6-11) exhibits enantiotropic smectic A and sX (unidentified smectic), poly(6-3) enantiotropic nematic mesophases, while poly(15-8) exhibits enantiotropic sA, chiral smectic C and sX (unidentified smectic) mesophases. Poly(6-11)-co-(15-8)X/Y exhibit a sA phase over the entire range of compositions. This mesophase displays a continuous dependence of copolymer composition with an upward curvature. Poly(15-8)-co-(6-3)X/Y from 10/0 to 3/7 displays an enantiotropic sA mesophase as their highest phase, while those with X/Y from 2/8 to 1/9 an enantiotropic cholesteric mesophase.
Download or read book Molecular Engineering of Liquid Crystal Polymers by Living Polymerization 13 Synthesis and Living Cationic Polymerization of 4 S 2 Methyl 1 Butyl Oxycarbonyl 4 omega Oxyalkyl 1 Vinyl Ether Biphenyl with Undecanyl and Hexyl Alkyl Groups written by and published by . This book was released on 1991 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: The synthesis and living cationic polymerization of 4-S( - )-2-methyl- 1-butyloxycarbonyl-4'(11-oxyundecanyl-1-vinyl ether)biphenyl (12-11) and 4-S( - )- 2-methyl-1-butyloxycarbonyl-4'-(6-oxyhexyl-1-vinyl ether)biphenyl (12-6) are described. Polymers with degrees of polymerization from four to twenty six and polydispersities equal and lower than 1.10 were synthesized and characterized by differential scanning calorimetry (DSC) and thermal optical polarized microscopy. When determined from first heating and cooling DSC scans, poly exhibit monotropic SA, SC* and SX (unidentified) mesophases over the entire range of molecular weights. When determined from second and subsequent heating and first and subsequent cooling scans, poly with degrees of polymerization equal to ten and lower than ten exhibit enantiotropic SA, SC* and SX mesophases, and crystallization on the heating scan, while those with higher degrees of polymerization exhibit enantiotropic SA, SC* and SX mesophases only.
Download or read book Molecular Engineering of Liquid Crystal Polymers by Living Polymerization 14 Synthesis and Characterization of Binary Copolymers of Omega 4 Cyano 4 Biphenyl oxyAlkyl Vinyl Ethers Containing Undecanyl and Hexyl Pentyl and Propyl and Undecanyl and Propyl Pairs of Alkyl Groups written by and published by . This book was released on 1991 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: Copolymerization represents the simplest synthetic technique which can be used to tailor make phase transitions of both main chain and side chain liquid crystalline polymers. Indeed, copolymerization was frequently employed to manipulate the phase transitions of side chain liquid crystalline polymers. However, most of the results reported in the literature can be considered only in a qualitative way, since there are only very few cases in which information about both copolymer composition and molecular weight are available. A general classification of side chain liquid crystalline copolymers was recently discussed in a review article. There are two main classes of side chain liquid crystalline copolymers. The first one refers to copolymers containing pairs of structural units with and without mesogenic units. This class of copolymers was extensively investigated. The second class refers to copolymers based on pairs of structural units containing mesogenic units in each one.
Download or read book Catalogus der tentoonstelling 60 jaren Nederlandse affiches written by and published by . This book was released on 1951 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Molecular Engineering of Liquid Crystalline Polymers by Living Polymerization 10 Influence of Molecular Weight on the Phase Transitions of Poly Omega 4 Cyano 4 Biphenyl oxy alkyl Vinyl Ethers s with Nonyl and Decanyl Alkyl Groups written by and published by . This book was released on 1990 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first goal of this series of publications is to provide a complete elucidation of the influence of molecular weight on the phase behavior of poly omega-(4-CYANO-4'-BIPHENYL)OXYaklyl vinyl ether s containing alkyl groups from ethyl to undecanyl. The goal of this paper is to describe the synthesis and living cationic polymerization of the last two monomers from this series, i.e., 9-(4-CYANO-4'-BIPHENYL)OXYnonyl vinyl ether (6-9) and 10-(4-CYANO- 4'-BIPHENYL)OXYdecanyl vinyl ether (6-10). The influence of molecular weight on their phase transitions will be discussed by comparison to that of 9-(4-CYANO- 4'-BIPHENYL)OXYdecanyl ethyl ether (8-10) which represents the model compounds of the monomeric structural units of poly (6-9) and poly (6-10). Then, the mesomorphic behavior of poly?w-(4-CYANO-4'-BIPHENYL)OXYalkyl vinyl ether s with alkyl groups containing from two to eleven methylenic units will be comparatively discussed at four different degrees of polymerization: 30, 23, 13 and 4. The implication of different phase transitions at various molecular weights on the molecular design of novel macromolecular architectures based on side charm liquid crystalline polymers is briefly discussed.
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1991 with total page 1652 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Molecular Engineering of Liquid Crystalline Polymers by Living Cationic Polymerization 21 Synthesis and Characterization of Poly 3 4 Cyano 4 Biphenyl oxy propyl Vinyl Ether Macromonomers written by and published by . This book was released on 1992 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes the synthesis and characterization of poly 3-4- CYANO-4'-BIPHENYL)OXYpropyl vinyl ether) POLY(6-3) macromonomers obtained by the functionalization of the growing chain end of the corresponding living polymer obtained by the initiation of the cationic polymerization of 3-4-CYANO- 4'BIPHENYL)OXYpropyl vinyl ether with CF3SO3H/S(CH3)2, with 2-hydroxy ethyl methacrylate POLY(6-3)-I, 2-2(2-ALLYLOXYETHOXY)ETHOXYethanol POLY 6-3-II and 10-undecen-1-ol POLY(6-3)-III.
Download or read book Molecular Engineering of Liquid Crystalline Polymers by Living Polymerization 5 Synthesis and Mesomorphic Behavior of Poly 2 4 Cyano 4 Biphenyl oxy ethyl Vinyl Ether co 8 4 Co 4 Biphenyl oxy octyl Vinyl Ether written by and published by . This book was released on 1990 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The synthesis and characterization of poly 2-(4-cyano-4 '-biphenyl) oxy ethyl vinyl ether poly(6-2), poly 8-(4-cyano-4'biphenyl)oxyocctyl vinyl ether poly(6-8) and poly (6-2-co6-8) X/Y (where X/Y is the molar ratio of the two monomeric structural units) with degrees of polymerization of about 10 and narrow molecular weight distribution are described. Both homopolymers and copolymers were prepared by living cationic polymerization and copolymerization of 6-2 and 6-8. During the first heating scan poly(6-2) presents an inverse monotropic s sub c mesophase. During subsequent heating and cooling scans, this polymer is amorphous regardless of the thermal history of the sample. Poly(6-8) exhibits an enantiotropic s sub a mesophase. Both during the first and subsequent haeting and cooling scans, the phase diagram which plots the dependence of mesomorphic transition temperatures as a function of copolymer composition presents a discontinuity.
Download or read book Molecular Engineering of Liquid Crystalline Polymers by Living Polymerization 9 Living Cationic Polymerization of 5 4 Cyano 4 Biphenyl Oxy pentyl Vinyl Ethers and 7 4 Cyano 4 Biphenyl oxy heptyl Vinyl Ether and the Mesomorphic Behavior of the Resulting Polymers written by and published by . This book was released on 1990 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: The synthesis and living cationic polymerization of 5-((4-cyano-4'- biphenyl)oxy)pentyl vinyl ether (6-5)and 7-((4-cyano-4'biphenyl)oxy)heptyl vinyl ether (6-7) are presented. The influence of molecular weight on the mesomorphic behavior of poly(6-5) and poly(6-7) is discussed and compared to that of 5-((4- cyano-4'-biphenyl)oxy)pentyl ethyl ether (8-5) and 7((4-cyano-4'-biphenyl)oxy) heptyl ethyl ether (8-7) which are models of the monomeric structural units of poly(6-5) and poly(6-7). Both (8-5) and (8-7) exhibit a monotropic nematic mesophase.
Download or read book Molecular Engineering of Liquid Crystalline Polymers by Living Polymerization 23 Synthesis and Characterization of AB Block Copolymers written by and published by . This book was released on 1992 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes the synthesis and characterization of AB block copolymers based on w-((4-cyano-4'-biphenyl)oxy)alkyl vinyl ether (6-n) with alkyl being ethyl (6-2), propyl (6-3), nonyl (6-9) and undecanyl (6-11) with 1H, 1H, 2H, 2H-perfluorodecyl vinyl ether (CF8), poly(6-n)-b-CF8)X/Y (where X/Y refers to the weight ratio of the two segments), and of 2-(4-biphenyloxy)ethyl vinyl ether (BEVE) with 1H, 1H, 2H, 2H-perfluoeodecyl vinyl ether, poly(BEVE-b- CF8)X/Y. They were prepared by living cationic polymerization and exhibit a narrow molecular weight distribution. All block copolymers display a microphase separated morphology when the A segment is in the liquid crystalline phase. Block copolymers based on 6-2, 6-3 and BEVE with CF8 exhibit a microphase separated morphology also in the melt phase of A and B block.
Download or read book Lux e tenebris novis radiis aucta hoc est revelationes factae Christophoro Kottero Christinae Poniatoviae Nicolao Drabicio written by and published by . This book was released on 1665 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Molecular Engineering of Liquid Crystalline Polymers by Living Polymerization 19 Synthesis and Characterization of Poly 2 4 Biphenyloxy Ethyl Vinyl Etherby written by and published by . This book was released on 1992 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: The synthesis and living cationic polymerization of 2-(4-biphenyloxy) ethyl vinyl ether (BEVE) are described. Polymers with degrees of polymerization from 3.8 to 22.1 and narrow molecular weight distribution were synthesized and characterized by differential scanning calorometry (DSC) and thermal optical polarized microscopy. When determined from their first DSC heating scans POLY(BEVE)s exhibit only a crystalline phase over the entire range of molecular weights. When determined from the second and first cooling scans, poly(BEVE) with a degree of polymerization of 3.8 exhibits an enantiotropic smectic mesophase and a crystallization process on the heating scan, while the polymers with degrees of polymerization from 4.7 to 8.1 exhibit only an enantiotropic smectic mesophase. The polymers with higher degrees of polymerization do not exhibit any mesophase. An explanation for this behavior is provided.
Download or read book Molecular Engineering of Liquid Crystal Polymers by Living Polymerization 15 Molecular Design of Reentrant Nematic Mesophases in Binary Copolymers of Omega 4 cyano 4 biphenyl oxy Alkyl Vinyl Ethers written by V. Percec and published by . This book was released on 1991 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The reentrant nematic phase was discovered in 1975 in low molar mass liquid crystals. Since then it received substantial theoretical and experimental interest. The first side chain liquid crystalline polymer exhibiting a nre phase was reported in 1986. This polymer was based on a polyacrylate backbone, six methylenic units in the flexible spacer, and 4-cyano-4'-oxybiphenyl side groups. In the mean time, several other polyacrylates containing mesogenic units with cyano groups and spacer lengths with five or six atoms were reported to exhibit the unusual i-n-SAd-nre sequence. So far, there are two copolymerization experiments with a monomer whose polymer exhibits a nre phase and a monomer whose polymer exhibits a n or SA mesophase.
Download or read book Molecular Engineering of Liquid Crystalline Polymers by Living Polymerization 6 Influence of Molecular Weight on the Phase Transitions of a 1 1 Copolymer of 2 4 Cyano 4 Biphenyl oxy ethyl Vinyl Ether and 8 4 Cyano 4 Biphenyl oxy octyl Vinyl Ether written by and published by . This book was released on 1990 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: A 1/1 molar ratio of 2-4-cyano-4'-biphenyl)oxyethyl vinyl ether (6-2) and 8-(4-cyano-4'biphenyl)oxyoctyl vinyl ether (6-8) was cationically copolymerized with the initiating system CF3SO3H/(CH3)2S in methylene chloride at 0C. All copolymers present narrow molecular weight distributions, and number average molecular weights which exhibit a linear dependence on Msub zero/Isub zero. Copolymers with degrees of polymerization lower than 14 exhibit an enantiotrpic nematic mesophase regardless of the thermal history of the sample. Copolymers with higher molecular weights exhibit an inverse monotropic smectic-A and an enantiotropic nematic mesophase in the first heating scan and only enantiotropic nematic mesophase in the subsequent heating scans. (TR).
