Rigid backbone polymers. XI. Solution phase-viscosity relationship

Using combined results of isothermal viscosity measurements and cross-polarized light microscopy on four polyisocyanate/solvent systems, the following were demonstrated: (a) an anisotropic phase appears, associated with a shoulder in the viscosity curve, at a concentration v lower than the peak viscosity at v; (b) the inversion from anisotropic inclusions in an isotropic matrix to isotropic inclusions in an anisotropic matrix, occurs at concentrations v > v and (c) the attainment of a single phase, microscopically anisotropic, occurs at v > v; where the viscosity is decreasing but has not yet reached its minimum. When the experiments were repeated with changes in temperature, the following were observed: (a) within each single phase the viscosity drops with increased temperature; (b) in the biphasic range, the total viscosity η⁰ remains about constant in the concentration range ≤ and increases with temperature in the range v > v; (c) in the interval v > v of the biphasic range, at constant temperature an increase in concentration decreases η⁰, and at constant concentration, a decrease in temperature lowers η⁰. Qualitative explanations of the observations are proposed.     

Rigid backbone polymers. X. Transitions in bulk polyisocyanates

Data obtained by hot-stage cross-polarized light microscopy and thermogravimetric analysis were used to plot a transition map for the poly(n-alkylisocyanate) homologous family. Most members had a low-temperature transition (or relaxation). The middle members of the family, with side-chain length of 4 ≤ n < 13 carbon atoms, exhibit a mesomorphic range of temperatures. Members with sidechains of n ≥ 13 in length, go directly from the low-temperature transition to the melting point without passage through a liquid crystalline state. A transition map for two homopolymers and a series of their copolymers, poly[x mol% n-butyl + (100-x)mol% p-anisole-3-propyl]isocyanate, was also prepared. The range of mesomorphicity as a function of composition and temperature is clearly indicated.     

Rigid rod polymers with regularly spaced silicon-centered phthalocyanine units in the backbone

We describe the synthesis of new rigid rod polymers possessing a backbone of silicon phthalo-cyanine units and stiff 4,4′-dioxybiphenyl or 2,6-dioxynaphthalene spacers. These modified phthalocyaninato-polysiloxane derivatives are characterised by mass, absorption and ¹³C-CPMAS spectroscopies, differential scanning calorimetry and X-ray powder diffractometry. UV/VIS spectra show only slight differences to the corresponding phthalocyanine monomers, which indicates the absence of excited state interactions between the chromophores within the polymer backbone.     

Rigid rod molecules as liquid crystal thermosets. I. Rigid rod amides

A series of rigid rod amide monomers based on 2,2′-disubstituted-4,4′-diaminobiphenyl were prepared and characterized by DSC and hot stage polarized light microscopy. The monomers were endcapped with maleimide, nadimide, and methylnadimide functionalities. With one exception, all of the materials could be thermally polymerized. Nematic liquid crystalline behavior was observed in three of the new materials which could be crosslinked in either the nematic or isotropic phase. Fast heating rates with hot stage polarized light microscopy were necessary to determine the melting and phase behavior before substantial crosslinking occurred during the heating process. One of the methylnadimide endcapped monomers also showed lyotropic liquid crystalline behavior.     

Amino acid-bearing ROMP polymers with a stereoregular backbone

The ruthenium-catalyzed ring-opening polymerization (ROMP) of 1-cyclobutenecarbonyl glycine methyl ester provides translationally invariant, head-to-tail ordered polymers. This polybutadiene backbone contains (within the limits of detection) only E-trisubstituted olefins, and it has no stereocenters that would serve as a source of structural ambiguities. Characterization of the polymer products indicates that they have polydispersities ranging from 1.2 to 1.6 and suggests that they are the products of a "living" polymerization. 1-Cyclobutenecarboxamide-derived ROMP polymers are excellent prospects for applications that require stereoregular chains functionalized with polar ligands.     

Synthesis of N-substituted phenoxazine polymers bearing vinyl backbone

Vinyl monomers bearing N-substituted phenoxazine or 2,8-dimethylphenoxazine units were synthesized starting with the corresponding phenoxazines. N-substituents were 2-vinylbenzyl-oxycarbonylethyl group prepared via 2-carboxyethyl group, 3-methacrylamido-, 3-acrylamido-, or 3-(4-styrenesulfonamido)-propyl group prepared via 3-aminopropyl group, vinylbenzyl, or 2-vinyloxyethyl group attached by the displacements of sodium salts of the phenoxazines to the chlorides, and 2-methacryloyl- or 2-acryloyl-oxyethyl group prepared via 2-hydroxyethyl group. Free-radical polymerixations of these novel monomers proceeded smoothly, except those with 2-vinyloxyethyl group, which were susceptible to BF₃-etherate. Changes of the visible absorption spectrum of iodine in THF with addition of the monomers and polymers were considerable, with the appearance of new absorption peaks or shoulders in major cases.     

Thermotropic liquid crystalline polymers. I. Cholesterol-containing polymers and copolymers

An approach to the creation of thermotropic cholesterol-containing liquid crystalline polymers by the chemical binding of cholesterol molecules with side chains of comblike polymers is presented. This type of structure permits a decrease in the steric hindrances provided by the backbone chains for the purpose of realizing the liquid crystalline state. A number of new cholesteric esters of poly(N-methacryloyl-ω-aminocarbonic acid)s (PChMAA-n) with different side-chain lengths (n = 2–11) as well as a series of copolymers of ChMA-n with n-alkylacrylates and n-alkylmethacrylates have been synthesized. The experimental evidence of liquid crystalline structure formation in these polymers in glass, viscoelastic, and fluid states is discussed. Molecular and supermolecular structures of cholesterol-containing comblike polymers have been studied and the model of macromolecular packing in the liquid crystalline state is proposed. It is shown that the existence of a layered order of side methylene groups together with ordering of cholesterol groups is necessary to the production of the liquid crystalline state in these polymers.     

Rigid rod polymers from liquid crystalline phthalocyanines

A number of alkoxy-substituted silicon-dihydroxy-phthalocyanines have been synthesized which form discotic mesophases depending on the side chain length. Metal salt catalyzed polycondensation only gives oligomers while polymer synthesis from activated monomers leads to reasonable high molecular weigths. Indications for the existence of mesophases in this polymer are given.     

Low surface energy polymers and surface active block polymers. I. t-butylphenyl containing polymers

Two new monomers in the 2-oxazoline series were synthesized and polymerized. These were 2-[4-(t-butyl)phenyl]-2-oxazoline ( I ) and 2-[(3-(3,5-di-t-butyl)phenoxy)propyl]-2-oxazoline ( II ). The polymer from I crystallized readily during bulk polymerization and showed T_m at 592 K (319°C). After annealing, the polymer showed a critical surface tension of 23.2 dyn/cm. Polymer from II was amorphous; hence, annealing showed little effect on contact angles. Block polymers were made with I (Xn = 10) and ethyl oxazoline (Xn = 6,20,60). Very sharp molecular weight distributions were obtained. All samples crystallized when annealed. The block polymer was an effective emulsifier for emulsion polymerization of butyl acrylate at 0.1%.     

An addition scheme of heat capacities of linear macromolecules. Carbon backbone polymers

It is shown that heat capacities of linear macromolecules consisting of all-carbon single-bonded backbones can be calculated from the appropriate contributions of substituted carbon atoms to a precision of about – 0.2±2.5% (155 data points), which is similar to the experimental precision. Heat capacity contributions of 42 groups are given over the full range of measurement and reasonable extrapolation. The quality of the addition scheme is tested on 16 series of measurements on homopolymers, copolymers and blends. The addition scheme works for all these different states of aggregation of the constituent groups. The basis of the addition scheme is discussed.

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Zusammenfassung Es wird gezeigt, daß Wärmekapazitäten von aus Hauptketten mit ausschließlich C-C-Einfachbindungen bestehenden Makromolekülen aus geeigneten Beiträgen der substituierten Kohlenstoffatome mit einer Genauigkeit bis etwa –0.2±2.5% (155 Datenpunkte) berechnet werden können, was der experimentellen Genauigkeit nahe kommt. Wärmekapazitätsbeiträge von 42 Gruppen wurden über den vollen Meßbereich hinweg und durch sinnvolle Extrapolation bestimmt und angegeben. Die Zuverlässigkeit des Additionsschemas wurde in 16 Meßreihen an Homopolymeren, Kopolymeren und Mischungen getestet. Das Additionsschema ist für alle diese verschiedenen Anordnungen der konstitutionellen Gruppen zutreffend. Die Grundlagen des Additionsschemas werden diskutiert.

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, , , , , –0,2 ±2,5% (155 ), . 42 - . 16 , . . .

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On leave from the University of Science and Technology of China, Hefei, Peoples Republic of China.

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This work was supported through the many years it took to assemble the needed experimental data by the National Science Foundation,-Polymers Program, Grant # DMR 8317097.     

Diffusion in glassy polymers. I

Synopsis The diffusion of six solvents in three crosslinked, glassy epoxy polymers is studied. Case II swelling and Fickian sorption are observed as two simple limiting cases. The mechanism of diffusion changes from one limit to another as the nature of the solvent or the crosslink density of the polymer is altered. With mixed solvents, properly chosen, a superposition of Fickian diffusion and case II swelling is observed.     

Synthesis of biodegradable conjugated polymers with controlled backbone flexibility

A series of flexible, highly bright fluorescent poly(p‐phenyleneethynylene)s (PPEs) was prepared by employing a disulfide containing nonconjugated monomer at various ratios under Sonogashira reaction conditions. PPEs with flexible linkers exhibited fluorescence properties comparable to those of a fully conjugated PPE when less than 50% of flexible monomers were incorporated into the backbone. To evaluate the self‐assembly properties of PPEs, a series of conjugated polymer nanoparticles (CPNs) was fabricated by treating PPEs with organic acids followed by dialysis. CPNs containing linkers exhibited different complexation behavior with polysaccharides, warranting further investigation into how flexibility and biodegradability of CPNs influence their cellular interaction and entry. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1403–1412     

Polyisocyanides derived from tripeptides of alanine

Helical polymers of isocyanotripeptides derived from alanine have been synthesized and their architectures studied in detail. The helical conformation of the polyisocyanotripeptides is stabilized by internal hydrogen-bonding arrays between the tripeptide side chains. The possibility of extending the well-defined hydrogen-bonded array, from dipeptide to tripeptide side chains, depends strongly on the stereochemistry of the constituent alanine amino acids, as has been shown by circular dichroism and IR studies. In polymers containing a weaker hydrogen-bonding array adjacent to the polymer backbone, due to steric interactions between the alanine methyl groups, a stronger second hydrogen-bonding array was present between the peptide bonds furthest away from the main chain, which is probably a result of stretching/compression of the helical-polymer conformation.     

Stretching globular polymers. I. Single chains

We review the force-extension behavior of polymers collapsed in poor solvent, modified to include the effects of semiflexibility and considered for globules with "ordered" and "disordered" internal structures. A series of ordered globules is used as a model for the unbinding of a disordered globule beneath its glass transition and for multiple-repeat proteins such as the poly-Ig-domain titin used in atomic force microscopy studies. These single-chain results form the foundation for the treatment of cross-linked networks of globular polymers.     

Metal coordination polymers. I. Synthesis and thermogravimetric analysis of beryllium phosphinate polymers

The preparation, properties, infrared, DTA, and TGA data are given for beryllium dimethyl-, tetramethylene-, di-n-butyl-, di-n-pentyl-, di-n-heptyl-, methylphenyl-, diphenyl-, and bispentafluorophenylphosphinates. Synthesis of dimeric beryllium acetylacetonyl phenyl-[o-methylcarboranyl (B₁₀)] phosphinate is reported. The beryllium phosphinates were prepared by the reaction of beryllium acetylacetonate with the appropriate phosphinic acid.     

Maleimide polymers. I. A polymeric color reaction

Certain copolymers of maleimide and N-substituted maleimides yield brilliant colors when treated with sufficiently strong basic reagents under nonhydrolytic conditions. For color generation, the copolymer must be capable of HX elimination. The chromophores which account for color probably result from the ionization of acidic protons in structures involving one or more double bonds conjugated with imide carbonyl. The analogy to the color reactions of aconitylanil is pointed out. Spectra covering the range of 330–700 mμ are presented for a number of copolymer–amine color-generating systems. The colors produced in base with radical-initiated polymaleimide and imidazole-initiated poly-N-alkylmaleimides as well as the absence of color with anionic polymaleimide and radical poly-N-alkylmaleimides are discussed in light of what is known about their polymerization kinetics and mechanisms. Corresponding maleic anhydride copolymer systems are mentioned.     

Evaluation of polymers based on a silicone backbone as pseudostationary phases for electrokinetic chromatography.

The feasibility of polymeric phases based on a silicone polymer backbone as pseudostationary phases for electrokinetic chromatography has been investigated. Silicone phases were studied because of the range of chemistries that could be developed based on these backbones, and because successful development of silicone phases would make it possible to employ much of the stationary phase chemistry developed in the past thirty years. Three silicone polymer structures have been investigated, but only one had sufficient aqueous solubility to permit application in electrokinetic chromatography. This phase was characterized by a variety of methods and was shown to be a mixture of partially hydrolyzed poly(bis-(3-cyanopropyl) siloxanes. When employed as a pseudostationary phase, this material provided selective and efficient separations. The electrophoretic mobility of the silicone polymer is greater than that of sodium dodecyl sulfate (SDS) micelles and poly(sodium 10-undecenylsulfate), providing an extended migration time range. A striking characteristic of the polymer is that the electrophoretic mobility is greater than typical electroosmotic mobilities. The chemical selectivity of the phase is significantly different from that of SDS micelles or poly(sodium 10-undecenylsulfate). The silicone phase is a more cohesive, basic and polar phase than SDS micelles. In buffers modified with a high concentration of organic solvents, the chromatographic properties of the silicone polymer are inferior to those of the poly(sodium 10-undecenylsulfate). The greatest limitation of silicone polymers for this application appears to be limited aqueous solubility, which will make it difficult to realize a family of such polymers with different chemical selectivities.     

Organosilane polymers. I. Poly(dimethylsilylene)

Poly(dimethylsilylene) higher polymers prepared by alkali metal coupling of purified dimethyldichlorosilane were found to be high melting, largely crystalline polymers, soluble in solvents at temperatures above 200°C.     

Heat-resistant polymers containing bipyridyl units. I. Polyimides

Polyimides containing bipyridyl units were synthesized. The bipyridyl units were successfully incorporated by polymerization of various bipyridyl diamines with aromatic tetracarboxylic acid dianhydrides. The resulting polyamic acids had inherent viscosities in the range 0.07 to 2.26, and they were converted to the polyimides by thermal cyclization. The polyimides containing the bipyridyl units exhibited varying degrees of solubility in dimethylacetamide and m-cresol and were found to be very soluble in dichloroacetic acid.