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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)

The objective of this investigation was to determine if engineering properties of soil-cement could be significantly improved by the addition of a relatively small amount of polymeric material. Polymer science has increased drastically over the last two decades and polymers have become increasingly useful in recent years. Composite materials using polymers have been used in several areas of engineering, and it was believed that positive results could be obtained when they were used in combination with soil-cement. Three soils were used in this investigation: a lean clay classified as CL by the Unified Soil Classification System (USCS), a fat clay classified as CH by the USCS, and a uniform grade sand classified as SP by the USCS. The stabilizers used included type I portland cement and two proprietary polymers. These two polymers were selected after a deliberate screening test involving numerous polymers. Indirect tensile and unconfined compressive tests were conducted on specimens containing 4, 6, and 8 percent portland cement plus 2 percent polymer. Results are presented showing the effects of polymers on tensile strength, compressive strength, density, tensile modulus of elasticity, and compressive modulus of elasticity. Correlations are also presented between tensile and compressive strengths and tensile and compressive moduli of cement-treated soils. Although conclusive results cannot be determined without extensive research using other polymers and other soils, it is concluded that polymers have a tremendous effect on soil-cement, and that further research should be initiated in order that the effects of various polymers on different soil types can be more accurately defined. (Author)

The synthesis and 'living' cationic polymerization of (2R, 3S)-2-fluoro-3-methylpentyl 4'-(8-vinyloxyoctyloxy)biphenyl-4-carboxylate (11-8) are described. Poly(11-8)s with degrees of polymerization from 4.3 to 15.7 and polydispersities less than or equal to 1.19 were synthesized and characterized by differential scanning calorimetry (DSC) and thermal optical polarized microscopy. All poly(11-8)s exhibit an enantiotropic S(sub c*) and an unidentified smectic (S(sub 1) phase. Poly(11-8)s with DP less than or equal 11.5 exhibit an additional enantiotropic unidentified smectic (S(sub 2)) phase. No S(sub A) phase could be detected in any of poly(11-8)s. The nature of mesophases exhibited by poly(11-8) was confirmed by the investigation of the phase diagram of the copolymers prepared from 11-8 and (2R, 3S)-2- fluoro-3-methylpentyl 4'-( 11 vinyloxyundecanyloxy)biphenyl-4 carboxylate (11-11). The S(sub c*) phase of these copolymers displays a continuous dependence of copolymer composition. jg

XXIV, 840 Seiten

This experimental study investigated the System Molding of Four Liquid Crystal Polymers, Vectra A 950, Vectra B 950, HX 4000, and Xydar SRT 500 and two High Temperature Engineering polymers, Polyetherimide (Ultem) and Polyphenylene Sulfide (Fortron) and evaluation of mechanical properties, tensile, flexural, and compression of molded samples.

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.

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.

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.

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.

The synthesis and living cationic polymerization of (2S, 3S)-(+)-2- chloro-3-methylpentyl 4'-(11-vinyloxyundecanyloxy)biphenyl-4-carboxylate (15-11) and (2S, 3S)-(+)-2-chloro-3-methylpentyl 4'-(8-vinyloxyoctyloxy)biphenyl-4- carboxylate (15-8) are described. Poly(15-11)s and poly(15-8)s with degrees of polymerization (DP) up to 25 and polydispersities lower than 1.15 were synthesized and characterized by differential scanning calorimetry (DSC) and thermal optical polarized microscopy. Over the entire range of molecular weights poly(15-11)s and poly(15-8)s exhibit enantiotropic smectic A (sA) and chiral smectic C (sC) mesophases. In addition, all poly(15-11)s exhibit a crystalline phase. Poly(15-8)s are noncrystallizable. However, poly(15-8)s with degrees of polymerization higher than 12 exhibit an unidentified sX mesophase. Poly(15-11- co-158)X/Y (where X/Y represents the molar ratio of monomer 15-11 to monomer 15-8) with DP of about 15 and polydispersities lower than 1.11 were also synthesized and characterized.

We report that microporous films (honeycomb films) can lead various types of cells to tissue formation. The honeycomb films were fabricated by applying a moist air to a spread polymer solution containing biodegradable polymers (poly(L-lactic acid) (PLLA) and poly((epsilon)-caprolactone) (PCL)) and an amphiphilic polymer. Hepatocytes were cultured on a self-supporting honeycomb film of PLLA. The hepatocytes formed a single layer of columnar shape cells with a thickness of 20 micrometer. The tissue formation of hepatocytes specifically occurred on the honeycomb film of PLLA not on a flat film of PLLA. Three dimensional tissue structures were formed when cells were cultured on both sides of the self supporting honeycomb film. Double layers of hepatocytes were obtained by the method. Striated tissues such as heart and blood vessel could be reconstructed by utilizing a stretched honeycomb film of PCL.

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.

In the project supported by the AFOSR YIP, my laboratory published 24 papers. The goal of this project was to establish the design criteria for elasticity and ductility in conjugated polymers and composites by analysis of the structural determinants of the mechanical properties. We developed coarse-grained molecular dynamics simulations that predicted the mechanical properties of conjugated polymers and polymer-fullerene composites. We elucidated the mechanical properties of a library of greater than 50 low-band gap polymers to determine molecular design rules for maximizing electronic performance with mechanical deformability. We also determined the effect of cyclic stretching on the microstructure and mechanical properties of conjugated polymers. We used many of these results to produce a new type of ultra-thin, skin-wearable solar cell that could survive many cycles of deformation without degrading significantly. Complementary to the molecular approaches for improving the mechanical robustness of stretchable organic electronics, we also explored the role of encapsulation and adhesion in electronic devices and found that a large increase in stretchability is possible with the use of a stretchable encapsulating layer.

Our investigations on the polymerization of mesogenic vinyl ethers are performed with the initiating system CF3SO3H/(CH3)2S which induces a living polymerization at 0C in methylene chloride. Presently, we are performing experiments which provide a complete understanding of the influence of molecular weight on the phase behavior of poly omega-(4-cyano-4'-biphenyl)oxyalkyl vinyl ether s with flexible spacers containing from two to eleven methylene units. This paper will describe our results on the influence of molecular weight on the behavior of poly 2-4-cyano-4'-biphenyl)oxyethyl vinyl ether (6-2), poly 3-4- cyano-4'-biphenyl)oxypropyl vinyl ether (6-3) and poly 4-4-cyano-4'-biphenyl) oxybutyl vinyl ether (6-4). Their phase behavior will be compared to that of the model compounds of their monomeric structural units. (TTL)

Our investigations on the polymerization of mesogenic vinyl ethers are performed with the initiating system CF3SO3H/(CH3)2S which induces a living polymerization at 0C in methylene chloride. Presently, we are performing experiments which provide a complete understanding of the influence of molecular weight on the phase behavior of poly omega-(4-cyano-4'-biphenyl)oxyalkyl vinyl ether s with flexible spacers containing from two to eleven methylene units. This paper will describe our results on the influence of molecular weight on the behavior of poly 2-4-cyano-4'-biphenyl)oxyethyl vinyl ether (6-2), poly 3-4- cyano-4'-biphenyl)oxypropyl vinyl ether (6-3) and poly 4-4-cyano-4'-biphenyl) oxybutyl vinyl ether (6-4). Their phase behavior will be compared to that of the model compounds of their monomeric structural units. (TTL)

Our investigations on the polymerization of mesogenic vinyl ethers are performed with the initiating system CF3SO3H/(CH3)2S which induces a living polymerization at 0C in methylene chloride. Presently, we are performing experiments which provide a complete understanding of the influence of molecular weight on the phase behavior of poly omega-(4-cyano-4'-biphenyl)oxyalkyl vinyl ether s with flexible spacers containing from two to eleven methylene units. This paper will describe our results on the influence of molecular weight on the behavior of poly 2-4-cyano-4'-biphenyl)oxyethyl vinyl ether (6-2), poly 3-4- cyano-4'-biphenyl)oxypropyl vinyl ether (6-3) and poly 4-4-cyano-4'-biphenyl) oxybutyl vinyl ether (6-4). Their phase behavior will be compared to that of the model compounds of their monomeric structural units. (TTL)

Our investigations on the polymerization of mesogenic vinyl ethers are performed with the initiating system CF3SO3H/(CH3)2S which induces a living polymerization at 0C in methylene chloride. Presently, we are performing experiments which provide a complete understanding of the influence of molecular weight on the phase behavior of poly omega-(4-cyano-4'-biphenyl)oxyalkyl vinyl ether s with flexible spacers containing from two to eleven methylene units. This paper will describe our results on the influence of molecular weight on the behavior of poly 2-4-cyano-4'-biphenyl)oxyethyl vinyl ether (6-2), poly 3-4- cyano-4'-biphenyl)oxypropyl vinyl ether (6-3) and poly 4-4-cyano-4'-biphenyl) oxybutyl vinyl ether (6-4). Their phase behavior will be compared to that of the model compounds of their monomeric structural units. (TTL)

This paper describes the synthesis of poly 11-4-cyano-4 '-biphenyl) oxyundecanyl vinyl ether-co-2-(4-cyano-4'biphenyl)oxyethyl vinyl ether A/B poly(6-11)-co-(6-2)A/B where A/B refers to the molar ratio between the monomers 6-11 and 6-2, with number average molecular weights above 15, by living cationic polymerization. The phase behavior of the resulting copolymers was discussed as a function of copolymer composition. Within this range of molecular weights, in the first heating scan poly(6-11) exhibits a melting and an enantiotropic s(A) phase, while poly(6-2) only a glass transition temperature. Depending on composition, poly(6-11-CO6-2)A/B either display an enantiotropic nematic, enantiotropic s(A) or both enantiotropic nematic and anantiotropic s(A) phases.

This paper describes the synthesis of poly 11-4-cyano-4 '-biphenyl) oxyundecanyl vinyl ether-co-2-(4-cyano-4'biphenyl)oxyethyl vinyl ether A/B poly(6-11)-co-(6-2)A/B where A/B refers to the molar ratio between the monomers 6-11 and 6-2, with number average molecular weights above 15, by living cationic polymerization. The phase behavior of the resulting copolymers was discussed as a function of copolymer composition. Within this range of molecular weights, in the first heating scan poly(6-11) exhibits a melting and an enantiotropic s(A) phase, while poly(6-2) only a glass transition temperature. Depending on composition, poly(6-11-CO6-2)A/B either display an enantiotropic nematic, enantiotropic s(A) or both enantiotropic nematic and anantiotropic s(A) phases.

This paper describes the synthesis of poly 11-4-cyano-4 '-biphenyl) oxyundecanyl vinyl ether-co-2-(4-cyano-4'biphenyl)oxyethyl vinyl ether A/B poly(6-11)-co-(6-2)A/B where A/B refers to the molar ratio between the monomers 6-11 and 6-2, with number average molecular weights above 15, by living cationic polymerization. The phase behavior of the resulting copolymers was discussed as a function of copolymer composition. Within this range of molecular weights, in the first heating scan poly(6-11) exhibits a melting and an enantiotropic s(A) phase, while poly(6-2) only a glass transition temperature. Depending on composition, poly(6-11-CO6-2)A/B either display an enantiotropic nematic, enantiotropic s(A) or both enantiotropic nematic and anantiotropic s(A) phases.

This paper discusses a strategy to control molecular stacking interactions in low-dimensional mixed valence materials by locking partially oxidized metallomacrocycles together in a face-to-face orientation. Thus, doping of the cofacially linked oligomers (M(Pc)O)n M = Si, Ge, Sn; Pc = phthalocyaninato -- with halogen (I2, Br2) or quinone (e.g., TCNQ, DDQ) electron acceptors produces robust, electrically conductive polymers with a wide range of stoichiometries and properties. The new materials have been studied by a variety of physical methods including X-ray diffraction, resonance Raman and infrared spectroscopy, ESR, static magnetic susceptibility, and variable-temperature four-probe electrical conductivity. Evidence is presented that some of the polymers have 'metal-like' conductivity in the stacking direction and that transport properties within the series can be readily manipulated by rational variation of lattice architecture (e.g., the identity of the metal, M) and acceptor characteristics. (Author)

Since the first examples of mesogenic vinyl ethers and liquid crystalline poly(vinyl ether)s were reported from our laboratory, several research groups became actively engaged in the synthesis of liquid crystalline poly(vinyl ether)s mainly because they can be polymerized by living cationic mechanism. So far, we have elucidated the influence of molecular weight on the phase transitions of poly(omega-((4-cyano-4'-biphenyl)oxy)alkyl vinyl ether)s with alkyl groups from ethyl to undecanyl. Binary copolymerization experiments performed with the same monomers at constant copolymer molecular weight allowed the molecular design of nematic, smectic A and reentrant nematic mesophases. Similar homopolymerization and copolymerization experiments were used to tailor make polymers exhibiting a chiral smectic C mesophase. In addition, it has been shown that many functional mesogenic vinyl ethers can be polymerized by our preferred initiating system CF3SO3H/S(CH3)2 in CH2Cl2(9). The experiments described so far required only a good control over the degree of polymerization and polydispersity of the polymer.

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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.

This article is from Journal of Functional Biomaterials , volume 3 . Abstract A recombinant 130 kDa dihemoglobin which is made up of a single-chain tetra-α globin and four β globins has been expressed as a soluble protein in E. coli. The sequence of the single chain tetra-α is: αI-Gly-αII-(SerGlyGly)5Ser-αIII-Gly-αIV. This dihemoglobin has been purified and characterized in vitro by size exclusion chromatography, electrospray mass spectroscopy, equilibrium oxygen binding, and analytical ultracentrifugation. The observed values of P50 and nmax for the dihemoglobin are slightly lower than those observed for the recombinant hemoglobin rHb1.1 (a “monohemoglobin” comprised of two β globins and an αI-Gly-αII diα-globin chain). Titration of the deoxy form of dihemoglobin with CO shows that all eight heme centers bind ligand.In vivo, dihemoglobin showed increased circulating halflife and a reduced pressor response in conscious rats when compared to rHb1.1. These observations suggest that dihemoglobin is an oxygen carrying molecule with desirable in vivo properties and provides a platform for an isooncotic hemoglobin solution derived solely from a recombinant source. A 260 kDa tetrahemoglobin has also been produced by chemical crosslinking of a dihemoglobin that contains a Lys16Cys mutation in the C-terminal α-globin subunit. Tetrahemoglobin also shows reduced vasoactivity in conscious rats that is comparable to that observed for dihemoglobin.

This article is from Journal of Functional Biomaterials , volume 3 . Abstract A recombinant 130 kDa dihemoglobin which is made up of a single-chain tetra-α globin and four β globins has been expressed as a soluble protein in E. coli. The sequence of the single chain tetra-α is: αI-Gly-αII-(SerGlyGly)5Ser-αIII-Gly-αIV. This dihemoglobin has been purified and characterized in vitro by size exclusion chromatography, electrospray mass spectroscopy, equilibrium oxygen binding, and analytical ultracentrifugation. The observed values of P50 and nmax for the dihemoglobin are slightly lower than those observed for the recombinant hemoglobin rHb1.1 (a “monohemoglobin” comprised of two β globins and an αI-Gly-αII diα-globin chain). Titration of the deoxy form of dihemoglobin with CO shows that all eight heme centers bind ligand.In vivo, dihemoglobin showed increased circulating halflife and a reduced pressor response in conscious rats when compared to rHb1.1. These observations suggest that dihemoglobin is an oxygen carrying molecule with desirable in vivo properties and provides a platform for an isooncotic hemoglobin solution derived solely from a recombinant source. A 260 kDa tetrahemoglobin has also been produced by chemical crosslinking of a dihemoglobin that contains a Lys16Cys mutation in the C-terminal α-globin subunit. Tetrahemoglobin also shows reduced vasoactivity in conscious rats that is comparable to that observed for dihemoglobin.

This article is from Journal of Functional Biomaterials , volume 3 . Abstract A recombinant 130 kDa dihemoglobin which is made up of a single-chain tetra-α globin and four β globins has been expressed as a soluble protein in E. coli. The sequence of the single chain tetra-α is: αI-Gly-αII-(SerGlyGly)5Ser-αIII-Gly-αIV. This dihemoglobin has been purified and characterized in vitro by size exclusion chromatography, electrospray mass spectroscopy, equilibrium oxygen binding, and analytical ultracentrifugation. The observed values of P50 and nmax for the dihemoglobin are slightly lower than those observed for the recombinant hemoglobin rHb1.1 (a “monohemoglobin” comprised of two β globins and an αI-Gly-αII diα-globin chain). Titration of the deoxy form of dihemoglobin with CO shows that all eight heme centers bind ligand.In vivo, dihemoglobin showed increased circulating halflife and a reduced pressor response in conscious rats when compared to rHb1.1. These observations suggest that dihemoglobin is an oxygen carrying molecule with desirable in vivo properties and provides a platform for an isooncotic hemoglobin solution derived solely from a recombinant source. A 260 kDa tetrahemoglobin has also been produced by chemical crosslinking of a dihemoglobin that contains a Lys16Cys mutation in the C-terminal α-globin subunit. Tetrahemoglobin also shows reduced vasoactivity in conscious rats that is comparable to that observed for dihemoglobin.

This article is from Journal of Functional Biomaterials , volume 3 . Abstract A recombinant 130 kDa dihemoglobin which is made up of a single-chain tetra-α globin and four β globins has been expressed as a soluble protein in E. coli. The sequence of the single chain tetra-α is: αI-Gly-αII-(SerGlyGly)5Ser-αIII-Gly-αIV. This dihemoglobin has been purified and characterized in vitro by size exclusion chromatography, electrospray mass spectroscopy, equilibrium oxygen binding, and analytical ultracentrifugation. The observed values of P50 and nmax for the dihemoglobin are slightly lower than those observed for the recombinant hemoglobin rHb1.1 (a “monohemoglobin” comprised of two β globins and an αI-Gly-αII diα-globin chain). Titration of the deoxy form of dihemoglobin with CO shows that all eight heme centers bind ligand.In vivo, dihemoglobin showed increased circulating halflife and a reduced pressor response in conscious rats when compared to rHb1.1. These observations suggest that dihemoglobin is an oxygen carrying molecule with desirable in vivo properties and provides a platform for an isooncotic hemoglobin solution derived solely from a recombinant source. A 260 kDa tetrahemoglobin has also been produced by chemical crosslinking of a dihemoglobin that contains a Lys16Cys mutation in the C-terminal α-globin subunit. Tetrahemoglobin also shows reduced vasoactivity in conscious rats that is comparable to that observed for dihemoglobin.

The goal of this research program has been to establish strategies for producing protein-based materials that contain amino acids not normally found in natural proteins. Efforts have been focused on amino acids with fluorinated, electroactive or conformationally constrained side chains, and have allowed us to prepare protein-based polymers with unique properties, including low surface energies and sensitivity to electrochemical signals. These developments have expanded in a substantial way the range of materials properties accessible via chemical or biological synthesis of polypeptides and artificial proteins.

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.

The present program was undertaken to evaluate cement chemistries more suitable for macrodefect-free cement materials. Therefore, the thrust of this work is oriented to the chemistry of advanced cements. Two strategies are being employed. The first is to modify conventional high alumina and portland cements to develop advanced properties. Such properties in this context include improvement in moisture sensitivity and extension of useful service range to temperatures higher than those tolerated by conventional organic polymers. The second strategy is to evaluate novel chemistries. This has included forming alkali zirconium phosphates at low temperature. This class of materials exhibits zero thermal expansion, is stable to high temperature and therefore may be useful in aerospace applications where dimensional stability is important.

This chapter discusses the molecular engineering of side chain liquid crystalline polymers mainly by living polymerization reactions. According to thermodynamic schemes, the polymer effect through its molecular weight and backbone flexibility can provide an overall change of entropy of the system. Consequently it can transform virtual mesophases into monotropic and enantiotropic mesophases. The control of molecular weight provided by living cationic polymerization of mesogenic vinyl ethers can be used successfully to tailor-make phase transitions like smectic A (SA), nematic (n) and re-entrant nematic (nre) in side chain liquid crystalline polymers and copolymers. Some additional examples of molecular engineering of side chain liquid crystalline polymers containing crown ethers and polypodants and self-assemblying side Chain liquid crystalline polymers are presented.

This chapter reviews the molecular engineering of main chain and side chain liquid crystalline polymers. Several factors influencing the phase transitions of liquid crystalline polymers are critically discussed. These include thermodynamics of phase transitions, isomorphism of liquid crystals, rigidity of rod-like mesogens and chemical heterogeneity of main chain liquid crystalline copolymers. The use of polyetherification and copolyetherification and of living cationic polymerization and copolymerization in the manipulation of phase transitions of liquid crystalline polymers is extensively discussed. This review also discusses several novel architectures such as liquid crystalline dendrimers and cyclic oligomers, liquid crystalline polymers containing crown ethers and polypodants, electron donor-acceptor complexes of discotic liquid crystalline polymers, as well as, self-assemblying supramolecular liquid crystalline polymers.

This China report contains articles on China's Progress in the Chemistry and Chemical Engineering of High Polymers.

The underlying premise of the research is that organic polymer films 1-100 micrometers in thickness composed of guest-host polymer materials or functional polymer materials exhibit useful optical, electro-optical or dielectric/electrical properties. Such films show promise as media for optical data-storage and processing and non-linear optics (NLO). However practical device materials require the properties to be optimized and their function (e.g. NLO activity) should be retained in time. Improved performance of organic films may be achieved through molecular design and molecular engineering and an understanding of the fundamental relationships between the macroscopic optical, electro-optical and dielectric properties and the molecular structure and molecular dynamics in the materials. To this end a major joint effort has been made for liquid crystalline side-chain (LCSC) polymers.

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.

In the project supported by the AFOSR YIP, my laboratory published 24 papers. The goal of this project was to establish the design criteria for elasticity and ductility in conjugated polymers and composites by analysis of the structural determinants of the mechanical properties. We developed coarse-grained molecular dynamics simulations that predicted the mechanical properties of conjugated polymers and polymer-fullerene composites. We elucidated the mechanical properties of a library of greater than 50 low-band gap polymers to determine molecular design rules for maximizing electronic performance with mechanical deformability. We also determined the effect of cyclic stretching on the microstructure and mechanical properties of conjugated polymers. We used many of these results to produce a new type of ultra-thin, skin-wearable solar cell that could survive many cycles of deformation without degrading significantly. Complementary to the molecular approaches for improving the mechanical robustness of stretchable organic electronics, we also explored the role of encapsulation and adhesion in electronic devices and found that a large increase in stretchability is possible with the use of a stretchable encapsulating layer.

The synthesis and living cationic polymerization of 4-((S(-)-2- methyl-1-butyl)oxycarbonyl)-4'-(8-oxyoctyl-1-vinyl ether)biphenyl are described. Polymers with degree of polymerization lower than 40 and polydispersities were synthesized and characterized by differential scanning calorimetry (DSC) and thermal optical polarized microscope. All polymers exhibit enantiotropic s sub A and s sub C* mesophases. Polymers with degrees of polymerization higher than 17 exhibit also an enantiotropic unidentified s sub X mesophase. Copolymers of 14-8 with 4-((S(-)-2-methyl-1-butyl)oxycarbonyl)-4'-(11-oxyundecanyl-1-vinyl ether) biphenyl were synthesized to cover the entire range of composition at a degree of polymerization of 15. The phase behavior of these copolymers was investigated and demonstrated a behavior similar to an ideal solution derived from the structural units. This copolymerization experiment allowed the synthesis of copolymers exhibiting, depending on the composition, a s sub C* mesophase from below 10 deg C to up to 50-80 deg C.

The synthesis and living cationic polymerization of 4-((S(-)-2- methyl-1-butyl)oxycarbonyl)-4'-(8-oxyoctyl-1-vinyl ether)biphenyl are described. Polymers with degree of polymerization lower than 40 and polydispersities were synthesized and characterized by differential scanning calorimetry (DSC) and thermal optical polarized microscope. All polymers exhibit enantiotropic s sub A and s sub C* mesophases. Polymers with degrees of polymerization higher than 17 exhibit also an enantiotropic unidentified s sub X mesophase. Copolymers of 14-8 with 4-((S(-)-2-methyl-1-butyl)oxycarbonyl)-4'-(11-oxyundecanyl-1-vinyl ether) biphenyl were synthesized to cover the entire range of composition at a degree of polymerization of 15. The phase behavior of these copolymers was investigated and demonstrated a behavior similar to an ideal solution derived from the structural units. This copolymerization experiment allowed the synthesis of copolymers exhibiting, depending on the composition, a s sub C* mesophase from below 10 deg C to up to 50-80 deg C.

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.

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.

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.

In the project supported by the AFOSR YIP, my laboratory published 24 papers. The goal of this project was to establish the design criteria for elasticity and ductility in conjugated polymers and composites by analysis of the structural determinants of the mechanical properties. We developed coarse-grained molecular dynamics simulations that predicted the mechanical properties of conjugated polymers and polymer-fullerene composites. We elucidated the mechanical properties of a library of 50 low-bandgap polymers to determine molecular design rules for maximizing electronic performance with mechanical deformability. We also determined the effect of cyclic stretching on the microstructure and mechanical properties of conjugated polymers. We used many of these results to produce a new type of ultra-thin, skin-wearable solar cell that could survive many cycles of deformation without degrading significantly. Complementary to the molecular approaches for improving the mechanical robustness of stretchable organic electronics, we also explored the role of encapsulation and adhesion in electronic devices and found that a large increase in stretchability is possible with the use of a stretchable encapsulating layer.

Electroconductive polymers (ECPs) have garnered increasing attention in the realms of tissue engineering and regenerative medicine due to their unique physicochemical properties, including their ability to conduct electrical signals. These polymers, with inherent conductivity mirroring that of native tissues, present a promising platform for scaffolds that can modulate cell behavior and tissue formation through electrical stimulation. The biocompatibility, tunable conductivity, and topographical features of ECPs enhance cellular adhesion, proliferation, and differentiation. Furthermore, their electrical properties have been shown to augment nerve regeneration, cardiac tissue repair, and musculoskeletal tissue formation. Combined with other biomaterials or biological molecules, ECP-based composites exhibit synergistic effects, promoting enhanced tissue regeneration. Moreover, the integration of ECPs with cutting-edge technologies such as 3D printing and microfluidics propels the design of sophisticated constructs for tissue engineering applications. This paper concludes with the challenges faced in the clinical translation of ECP-based scaffolds and provides perspectives on the future trajectory of ECPs in regenerative medicine. The synthesis of ECPs with emerging biotechnologies has the potential to revolutionize treatments, bridging the gap between traditional regenerative approaches and sophisticated bioelectronic remedies.

While there have been several studies reported in the literature of the structure and properties of organic/inorganic hybrid materials prepared by 'sol-gel' chemistry, less is known about how solution conditions influence copolymerization kinetics and material nanostructure. We are developing kinetic polymerization models for structure development of this class of materials. We use (29)Si nuclear magnetic resonance spectroscopy to monitor the concentrations of differently hydrolyzed and connected silicon sites, and fit integrated sets of differential equations to these concentrations to quantify kinetic trends as monomers and solution conditions are varied.

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.

Hyperbranched polymers of unique compositions were studied for their mechanical properties and degradation behaviors. Highly branched polymeric architectures have been shown to exhibit properties that are unique to those of linear polymer materials. In the studies supported under this grant, hyperbranched polycarbonates were designed as analogs to common engineering polymers to investigate the effects of branching upon the chain-chain packing and cooperative motions. Remarkably, the local chain-chain interactions were quite similar for hyperbranched and linear polymer isomers. In another design, hyperbranched poly(silyl ester)s were studied as hydrolytically-degradable polymers to determine the effects of branching upon the degradation profile. The hyperbranched poly(silyl ester)s degraded by a two step degradation profile, whereas the analogous linear polymer gave smooth molecular weight loss with time. The result of these undertakings was the preparation of new materials and the acquisition of improved understanding of the structural conformation, three-dimensional solid-state packing, and physical and mechanical properties of highly-branched polymers.

Hyperbranched polymers of unique compositions were studied for their mechanical properties and degradation behaviors. Highly branched polymeric architectures have been shown to exhibit properties that are unique to those of linear polymer materials. In the studies supported under this grant, hyperbranched polycarbonates were designed as analogs to common engineering polymers to investigate the effects of branching upon the chain-chain packing and cooperative motions. Remarkably, the local chain-chain interactions were quite similar for hyperbranched and linear polymer isomers. In another design, hyperbranched poly(silyl ester)s were studied as hydrolytically-degradable polymers to determine the effects of branching upon the degradation profile. The hyperbranched poly(silyl ester)s degraded by a two step degradation profile, whereas the analogous linear polymer gave smooth molecular weight loss with time. The result of these undertakings was the preparation of new materials and the acquisition of improved understanding of the structural conformation, three-dimensional solid-state packing, and physical and mechanical properties of highly-branched polymers.

Hyperbranched polymers of unique compositions were studied for their mechanical properties and degradation behaviors. Highly branched polymeric architectures have been shown to exhibit properties that are unique to those of linear polymer materials. In the studies supported under this grant, hyperbranched polycarbonates were designed as analogs to common engineering polymers to investigate the effects of branching upon the chain-chain packing and cooperative motions. Remarkably, the local chain-chain interactions were quite similar for hyperbranched and linear polymer isomers. In another design, hyperbranched poly(silyl ester)s were studied as hydrolytically-degradable polymers to determine the effects of branching upon the degradation profile. The hyperbranched poly(silyl ester)s degraded by a two step degradation profile, whereas the analogous linear polymer gave smooth molecular weight loss with time. The result of these undertakings was the preparation of new materials and the acquisition of improved understanding of the structural conformation, three-dimensional solid-state packing, and physical and mechanical properties of highly-branched polymers.