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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.

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.

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.

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.

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.

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.

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.

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.

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.

This article is from International Journal of Nanomedicine , volume 9 . Abstract This study presents an innovative method for creating a highly porous surface with nanoscale roughness on biologically relevant polymers, specifically polyurethane (PU) and polycaprolactone (PCL). Nanoembossed polyurethane (NPU) and nanoembossed polycaprolactone (NPCL) were produced by the casting of PU and PCL over a plasma-deposited, spiky nanofeatured crystalline titanium (Ti) surface. The variables used in the process of making the spiky Ti surface can be altered to change the physical properties of the spiky particles, and thus, the cast polymer substrate surface can be altered. The spiky Ti surface is reusable to produce additional nanopolymer castings. In this study, control plain PU and PCL polymers were produced by casting the polymers over a plain Ti surface (without spikes). All polymer surface morphologies were characterized using both scanning electron microscopy and atomic force microscopy, and their surface energies were measured using liquid contact angle measurements. The results revealed that both NPU and NPCL possessed a higher degree of nanometer surface roughness and higher surface energy compared with their respective unaltered polymers. Further, an in vitro study was carried out to determine chondrocyte (cartilage-producing cells) functions on NPU and NPCL compared with on control plain polymers. Results of this study provided evidence of increased chondrocyte numbers on NPU and NPCL compared with their respective plain polymers after periods of up to 7 days. Moreover, the results provide evidence of greater intracellular protein production and collagen secretion by chondrocytes cultured on NPU and NPCL compared with control plain polymers. In summary, the present in vitro results of increased chondrocyte functions on NPU and NPCL suggest these materials may be suitable for numerous polymer-based cartilage tissue-engineering applications and, thus, deserve further investigation.

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.

This article is from Nanoscale Research Letters , volume 9 . Abstract In this work, an influence of bovine serum albumin proteins grafting on the surface properties of plasma-treated polyethylene and poly-l-lactic acid was studied. The interaction of the vascular smooth muscle cells with the modified polymer surface was determined. The surface properties were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, nano-LC-ESI-Q-TOF mass spectrometry, electrokinetic analysis, and goniometry. One of the motivations for this work is the idea that by the interaction of the cell with substrate surface, the proteins will form an interlayer between the cell and the substrate. It was proven that when interacting with the plasma-treated high-density polyethylene and poly-l-lactic acid, the bovine serum albumin protein is grafted on the polymer surface. Since the proteins are bonded to the substrate surface, they can stimulate cell adhesion and proliferation.

XXIV, 840 Seiten

XXIV, 840 Seiten

XXIV, 840 Seiten

XXIV, 840 Seiten

XXIV, 840 Seiten

XXIV, 840 Seiten

XXIV, 840 Seiten

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.

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 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 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 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 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 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 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 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 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 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.

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 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 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 Biological Engineering , volume 7 . Abstract The complex nature of in vivo gene transfer establishes the need for multifunctional delivery vectors capable of meeting these challenges. An additional consideration for clinical translation of synthetic delivery formulations is reproducibility and scale-up of materials. In this review, we summarize our work over the last five years in developing a modular approach for synthesizing peptide-based polymers. In these materials, bioactive peptides that address various barriers to gene delivery are copolymerized with a hydrophilic backbone of N-(2-hydroxypropyl)methacrylamide (HPMA) using reversible-addition fragmentation chain-transfer (RAFT) polymerization. We demonstrate that this synthetic approach results in well-defined, narrowly-disperse polymers with controllable composition and molecular weight. To date, we have investigated the effectiveness of various bioactive peptides for DNA condensation, endosomal escape, cell targeting, and degradability on gene transfer, as well as the impact of multivalency and polymer architecture on peptide bioactivity.

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 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 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.

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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.

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.

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.

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.

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.

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.

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.

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.

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.

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