Self-regulating polycondensations. IV. Ordered oxadiazole-imide copolymers

Ordered oxadiazole-imide copolymers are prepared from simple aminobenzhydrazide monomers by a step-wise reaction which begins with the condensation of a diacid chloride to produce in situ a diamine containing hydrazide linkages. The in situ diamine is then reacted with a dianhydride to yield an ordered hydrazide-amic-acid copolymer; this precursor is converted by heating to the ordered heterocycle copolymer. Polymers prepared via this manner are identical in properties to those obtained by the reaction of a dianhydride with a diamine containing hydrazide linkages preformed by a straight forward synthesis from a dinitro precursor. Fibers spun from the soluble precursor polymers were converted via cyclodehydration to thermally stable fibers. Another polyoxadiazole-imide was produced in similar fashion; e.g., an aminobenzhydrazide was reacted with the acid chloride of trimellitic anhydride to yield an in situ AB monomer which was polymerized to yield a precursor polyhydrazide-amic-acid, which in turn was converted by cyclodehydration to an AB type polyoxadiazole-imide. Additional examples are cited of the formation of polymers from the in situ intermediates produced by the “self-regulating” reaction of aminobenzhydrazides with acid chlorides followed by polycondensation with difunctional monomers.     

Preparation and properties of aromatic polyamide-esters from aminophenols and aromatic diacid chlorides

Aromatic polyamide-esters of moderately high molecular weight were prepared from various combinations of three aminophenols (m- and p-aminophenol, and 4-(4′-aminophenoxy) phenol) and two aromatic diacid chlorides (isophthaloyl and terephthaloyl) by interfacial polycondensation in a cyclohexanone/water system and two-phase polycondensation in a dichloromethane/water system with phase-transfer catalysts. The solution polycondensation in dichloromethane/N,N-dimethylacetamide was also successful for the production of high-molecular-weight polymers. The solubility of the aromatic polyamide-esters varied markedly with polymer structure. Except for two polyamide-esters derived from terephthaloyl chloride, all the other polymers were almost amorphous. These polymers had glass transition temperatures at around 200°C and showed 10% weight losses at about 400°C in both air and nitrogen atmospheres.     

Preparation and properties of N-phenylated aromatic polyamide-esters from anilinophenols and aromatic diacid chlorides

N-Phenylated aromatic polyamide-esters with high molecular weights were synthesized by the high-temperature solution polycondensation in nitrobenzene at 200°C from combinations of m- and p-anilinophenol and isophthaloyl and terephthaloyl chloride. Reaction variables such as monomer concentration, solvent, temperature, and time were studied to optimize the reaction conditions for the preparation of high molecular weight polymers. Some of the N-phenylated aromatic polyamide-esters have glass transition temperatures around 190°C and good solubility in chlorinated and amide solvents. These polymers gave transparent flexible films by solution-casting. Copolymers from p-anilinophenol and the two diacid chlorides were also synthesized and characterized.     

Pyrimidine based carboxylic acid terminated aromatic and semiaromatic hyperbranched polyamide-esters: synthesis and characterization

Carboxylic acid terminated aromatic and semiaromatic hyperbranched polyamide-esters (HBPAEs) containing pyrimidine moieties were prepared by polycondensation of 4-hydroxy-2,6-diaminopyrimidine (CBB′) to a double molar ratio of various diacid chlorides (A₂) without any catalyst. The products were soluble in organic solvents, such as N,N-dimethylformamide, N-methyl-2-pyrrolidone and displayed glass transition temperature (T_g) between 180 and 244 °C. The polymerization products have been investigated with FTIR, ¹H and ¹³C NMR analyses and the degree of branching was higher than 60%. Amorphous polymers had inherent viscosity (η_inh) ranging between 0.21-0.28 dL/g and had excellent thermal stability with 10% weight loss at 346-508 °C.     

Ring‐opening polycondensations

Ring‐opening polycondensation is a novel synthetic strategy using heterocycles of any ring size having two reactive bonds as bifunctional monomers in step‐growth polymerizations. The first part of this article reviews previous publications. The previous studies mainly dealt with syntheses of polyesters from tin‐containing macrocycles including cyclic polylactones. These tin‐containing cyclic oligomers or polymers were easily obtained in two ways, either by ring‐closing polycondensation of dibutyltin compounds with preformed diols or by ring‐expansion polymerizations of lactones by means of cyclic tin‐initiators. The second part of this article presents new results which deal with ring‐opening polycondensations of silicon containing macrocycles derived from oligo(ethylene glycol)s. In these cases the chain growth proceeds by elimination of dimethyl dichlorosilane. In addition to syntheses of homopolyesters, copolycondensations with silylated or stanylenated monomers were studied. Finally, the thermodynamical aspects of ring‐opening polycondensations will be discussed.     

Distributions in nonself-condensing polycondensations: A kinetic approach

The size distributions of a number of different polycondensations with nonself-condensing monomers were calculated by a kinetic method. The results of linear polycondensations with and without reversibility or stoichiometry and of multifunctional polycondensations are exactly the same as those obtained by Flory with probability methods and do not differ, when comparable, from the size distributions produced by the polycondensation of self-condensing monomers. Size distributions were also obtained for reactions in which the order of reaction changes with conditions or during reaction. These results clearly show that a Flory distribution is obtained as long as the principle of equal reactivity applies at any given instant, although this reactivity may vary in the course of the reaction.     

Macrocycles IV. Macrocyclic polylactones as bifunctional monomers for polycondensations

Tin containing macrocyclic polylactones were prepared by di-n-butyl-2-stanna-1,3-dioxepane-initiated polymerizations of ε-caprolactone in bulk. The average ring size was varied from 10 to 100 monomer units via the monomer/initiator (M/I) ratio. Addition of terephthaloyl or sebacoyl chloride to the in situ prepared macrocycles yielded polycondensates under elimination of di-n-butyl tin dichloride. The molecular weights increased with the reaction temperature (e.g., 80–140°C) and with the size of the macrocycles. Number-average molecular weights (M_ns) up to 90,000 and polydispersities between 1.65 and 2.0 were obtained. Further polycondensations were conducted with isophthaloyl chloride, 4,4′-biphenyldicarbonylchloride and 4,4′-phenylenebisacryloylchloride. Several polycondensations were performed with macrocyclic poly (δ-valerolactone) and poly (β-D ,L -butyrolactone). In those cases the increase of the molecular weight was lower. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1373–1378, 1998     

New high-temperature polymers. II. Ordered aromatic copolyamides containing fused and multiple ring systems

Symmetrical diamines, containing preformed carbonamide linkages, were prepared by reacting nitrobenzoyl chlorides with aromatic diamines and reducing the dinitro intermediates. The diamines were polymerized with aromatic diacid chlorides to give wholly aromatic ordered copolyamides of exceptionally high thermal stability. Ordered diamines were prepared containing only phenylene units as the aromatic portion, and others containing phenylene and naphthylene or biphenylene groups. Low-temperature solution polymerization of these diamines with isophthaloyl chloride, 4,4′-bibenzoyl chloride, or 2,6-naphthalenedicarbonyl chloride, gave thirteen ordered copolyamides, each containing a naphthylene and/or biphenylene group in its repeating unit. Differential thermal analyses and thermogravimetric analyses showed these polymers to have melting points or decomposition temperatures of from 420 to over 500°C. Films of one of the polymers had a breakdown voltage of 3000 v./mil at 180°C. Fibers of the same composition had tenacities of up to 8 g/den.; a 5.5 g/den. sample retained 85% of its tenacity after 17 hr. at 300°C. and 21% after 9 days.     

Preparation and properties of ordered and random polyamide-esters from 4-(4-amino-α,α-dimethylbenzyl)phenol and aromatic diacyl chlorides

Random polyamide-esters were prepared directly by the interfacial and solution polycondensation of 4-(4-amino-α,α-dimethylbenzyl)phenol (I) with iso- and terephthaloyl chlorides. Authentic samples of ordered polyamide–esters with an amide-amide–ester-ester structure were synthesized by the two-step procedure; that is, the preparation of amide–bisphenol monomers from I and subsequent polycondensation with aromatic diacyl chlorides. The random and ordered polyamide–esters differed from one another with respect to solubility in organic solvents and glass transition temperature, whereas all the random and ordered polymers were of equal low crystallinity. All of these polymers began to decompose around 350°C in both air and nitrogen atmospheres.     

Interpenetrating Nets: Ordered,Periodic Entanglement

Independent one-, two-, and even three-dimensional nets interpenetrate each other in many solid-state structures of polymeric, hydrogen-bonded nets and coordination polymers. For example, the interpenetration of the adamantane units of two diamondlike nets is shown on the right. A detailed and systematic examination of many interpenetrating nets of this kind is made, and implications for crystal engineering are discussed.     

Simulation of reversible polycondensations with monomer having reactivity different from that of higher homologs

Reversible AB-type polycondensations have been simulated in a batch reactor where the monomer reacts with itself or any higher oligomer with a rate constant R times that for higher mers. Similarly, the rate of reaction of the condensation product with an ? AB? group at the end of a polymer chain has been assumed to be R' times that with an “internal” ? ? AB? ? group. The variation of the number-average chain length μ_n with time (until equilibrium is reached) has been obtained. μ_n is found to be lower and the polydispersity index higher in the presence of the reverse reactions. Where the equilibrium conversions are high enough, a split in the molecular-weight distribution (MWD) curves is observed for even- and odd-order homologs for R < 1, though this effect is considerably diminished as compared with that in similar irreversible polycondensations. It is also found that the most probable distribution does not adequately represent the MWD when the functional groups violate the equal-reactivity hypothesis and number-average chain lengths are relatively small.     

Ordered mesoporous metal oxides: synthesis and applications

Great progress has been made in the preparation and application of ordered mesoporous metal oxides during the past decade. However, the applications of these novel and interesting materials have not been reviewed comprehensively in the literature. In the current review we first describe different methods for the preparation of ordered mesoporous metal oxides; we then review their applications in energy conversion and storage, catalysis, sensing, adsorption and separation. The correlations between the textural properties of ordered mesoporous metal oxides and their specific performance are highlighted in different examples, including the rate of Li intercalation, sensing, and the magnetic properties. These results demonstrate that the mesoporosity has a direct impact on the properties and potential applications of such materials. Although the scope of the current review is limited to ordered mesoporous metal oxides, we believe that the information may be useful for those working in a number of fields.     

Self-regulating enzyme-nanotube ensemble films and their application as flexible electrodes for biofuel cells

Nanostructured carbons have been widely used for fabricating enzyme-modified electrodes due to their large specific surface area. However, because they are random aggregates of particular or tubular nanocarbons, the postmodification of enzymes to their intrananospace is generally hard to control. Here, we describe a free-standing film of carbon nanotube forest (CNTF) that can form a hybrid ensemble with enzymes through liquid-induced shrinkage. This provides in situ regulation of its intrananospace (inter-CNT pitch) to the size of enzymes and eventually serves as a highly active electrode. The CNTF ensemble with fructose dehydrogenase (FDH) showed the oxidation current density of 16 mA cm(-2) in stirred 200 mM fructose solution. The power density of a biofuel cell using the FDH-CNTF anode and the Laccase-CNTF cathode reached 1.8 mW cm(-2) (at 0.45 V) in the stirred oxygenic fructose solution, more than 80% of which could be maintained after continuous operation for 24 h. Application of the free-standing, flexible character of the enzyme-CNTF ensemble electrodes is demonstrated via their use in the patch or wound form.     

Synthesis and properties of hyperbranched polyamide-esters derived from 1,3,5-tris(4′-hydroxyphenylcarbamoyl)benzene

A novel aromatic triol was synthesized and polycondensed with various diacid chlorides resulting in the preparation of a series of hydroxy-terminated hyperbranched polyamide-esters without gelation. Structure and degree of branching of the ensuing polymers were confirmed by FTIR, ¹H and ¹³C NMR analyses. These thermally stable polymers were found to be soluble in aprotic solvents. Inherent viscosities and T_g values lie in the range of 0.15-0.21 dL/g and 74-112 °C, respectively.     

509—Ordered protomembranes

Lipid-like structures synthesized according to the Cold Theory of the origins of life self-assemble in multitudes of stable microspheres. The walls of the microspheres present membrane-like properties. Optical (conventional and polarized light images) and electron microscope (conventional and freeze-fracture replication techniques) clearly show order and bilayer structure in the wall-membrane of the vesicles.     

有序纳米金颗粒的多层组装

采用LB技术组装了一种三维有序的由十八胺修饰的纳米金颗粒多层结构.这是一种新的组装纳米颗粒三维有序聚集体的方法.为了扩大这种方法的适用范围,在组装过程中,将有机小分子1-苯基-5-巯基四氮唑引进结构,形成了新的纳米金颗粒多层聚集体.这两种多层膜经透射电子显微镜和小角X射线衍射测量证明构成多层膜的单层膜上的纳米金颗粒是有序的,并且颗粒在层与层之间的排列也是有序的.