Synthesis of polyheterocycles on the basis of poly-functional monomers and study of their characteristics

Application of polyfunctional monomers in the course of polycondensation allows to synthesize different types of polymers using different activity of functional groups. It is possible in this case to vary to a large extent the characteristics of the obtained polymers. The presence of functional groups of different activity in one monomer also allows to modify it by introduction of new fragments for subsequent use in polycondensation or polymerization reactions. The abovementioned is confirmed by the example of using trimellitic anhydride and a number of alicyclic tetracarbonic dianhydrides. Trimellitic anhydride is directly used for synthesis of polymers and also modified for preparation of new derivatives. The perspective of using alicyclic tetracarbonic dianhydrides for synthesis of heterocycles has been shown. Varying the monomer nature and conditions of a polycondensation reaction, polymers with different specific characteristics have been obtained: heat-resistant, high- and low-fusible, soluble, incombustible, film-forming, fiber-forming, binding for glass-plastics.     

Copolyamide-imides of controlled microstructure. Effect of reaction conditions on regularity and properties

Aromatic polyamide-imides, based on trimellitimide and 4,4′-diphenylmethane and with different degrees of order, have been obtained from symmetric and asymmetric monomers. The polymers have been prepared by two general methods: (1) low temperature solution polycondensation of diamines and carboxylic acid derivatives; and (2) high temperature solution polycondensation of diisocyanates and dicarboxylic acids. High field ¹H-NMR has been used to elucidate the chemical structures of monomers and polymers and to estimate quantitatively the degree of order and the distribution of head-to-head, tail-to-tail (amide-amide, imide-imide) and head-to-tail (amide-imide) units. The influences of microstructure and other molecular features on some properties of the polymers have also been investigated.     

Asymmetric polymerization of methacrylates

The syntheses of optically active polymers having helical conformation from bulky methacrylates are reviewed focusing on selected topics. The monomers include triphenylmethyl methacrylate and its analogues. Asymmetric anionic polymerization of the monomers gives isotactic, optically active polymers having a helical structure with excess helicity. The isotactic content and the extent of helical‐sense excess depend on the monomer structure and the reaction conditions. In the case of methacrylates, completely isotactic and single‐handed helical polymers can be produced by asymmetric anionic polymerization (helix‐sense‐selective polymerization). Asymmetric radical polymerization is also possible for this class of monomer. Some of the helical polymers show chiral recognition ability toward a wide range of racemic compounds. Polymers having main‐chain configurational chirality are also discussed.     

Thermotropicity of fully aromatic polyesters based on 3,4′-dicarboxydiphenyl ether

3,4′-Substituted aromatic monomers, consisting of two phenylene units joined together by linking groups such as ketone or methylene, have recently been used for the preparation of quasi-rigid fully aromatic thermotropic polymers, based on conformational isomerism, with accessible transition temperatures. In this work the polyester of 3,4′-dicarboxydiphenyl ether and hydroquinone is considered: an Ullmann condensation has been carried out for the preparation of the asymmetric monomer, and low-temperature solution polycondensation has been used to synthesize the polymer. Although a liquid crystalline behavior could be expected, the polyester melts to an isotropic phase. Several copolymers have been prepared, by partially substituting either the asymmetric monomer with terephthalic acid or hydroquinone with different diphenols. The attempt to decrease the stability of the crystalline phase did not lead to significant results. The appearance of the nematic phase in some samples has been attributed to an increased chain stiffness, expressed in terms of persistence length as derived from molecular dynamics (MD) simulations.     

Narrow molecular weight distribution of condensation polymers achieved by adding monomers in many batches

The Z transform method has been used to calculate the molecular weight distribution (MWD) of condensation polymers. The MWD obtained by using Z transform is explicitly discrete. The method is illustrated for two cases: (1) further polycondensation of AB prepolymers with certain initial MWD, and (2) polycondensation of AB and Ar (r is the number of A type functional groups) monomers where AB monomers are added in several batches. In the latter case, it is found that the resulting MWD is much narrower than that of one-batch polycondensation. The trick of producing narrow MWDs of condensation polymers is merely a consequence of keeping AB monomer concentration as low as possible during the reaction in order to suppress the condensation reaction between monomeric AB molecules. The theoretical prediction has been confirmed by Monte Carlo simulation. Therefore, it provides a new possible technique for obtaining narrow MWD polymers through polycondensation reactions.     

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.     

Mixtures of lattice polymers with structured monomers

The influence of monomer structure on the thermodynamic properties of lattice model polymer blends is investigated through Monte Carlo computations. The model of lattice polymers with monomer structure has been used extensively in the context of the lattice cluster theory (LCT), a thermodynamic theory for polymer mixtures in the liquid state. The Monte Carlo computations provide the first unequivocal test of the accuracy of the LCT predictions for binary mixtures of polymers with structured monomers. Four types of monomer structures are analyzed, corresponding to to the monomers of polyethylene, polypropylene, polyethylethylene, and polyisobutylene (PIB). Most computations use chains with M=12 and 24 beads and the total volume fraction of the beads is phi=0.6. Both structurally symmetric and asymmetric blends are investigated. For the symmetric case, the predictions of the LCT for the energies of mixing and the liquid-liquid coexistence curves are in qualitative agreement with the Monte Carlo computations, except for the PIB/PIB symmetric blend. For structurally asymmetric blends, the LCT does not capture contributions to the energy of mixing arising solely from structural differences between the components. Computational estimates of the nonideal entropy of mixing indicate that the LCT also underestimates the entropic cost of mixing chains with different structures, thus explaining some discrepancies between the theoretical and the Monte Carlo liquid--liquid coexistence curves.     

A convenient room temperature polycondensation toward hyperbranched AB2‐type all‐aromatic polyesters with phenol terminal groups

As a convenient alternative to the classical melt polycondensation the one‐pot solution polycondensation of suitable AB₂ monomers under mild conditions has been successfully adapted to hyperbranched all‐aromatic polyester with phenol terminal groups. The polymerization was performed in solution at room temperature directly using commercially available 3,5‐dihydroxybenzoic acid as monomer and 4‐(dimethylamino) pyridinium 4‐tosylate as catalyst to suppress the formation of N‐acylurea. Different carbodiimides as coupling agents were investigated to find the optimal esterification conditions. The polymers have been characterized extensively and were compared with their well‐known analogs synthesized in melt. The characterization was carried out by NMR spectroscopy, size exclusion chromatography, and asymmetric flow‐field flow fractionation as an alternative separation technique for multifunctional polymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5158–5168, 2009     

Configurational rules governing the stereochemical control of chiral initiators in ring-opening polymerizations of heterocyclic monomers

Configuration rules were established for the polymerization of cyclic monomers with chiral initiators. The latter recognize in the monomer an asymmetric carbon of homochiral configuration. The chirality of the initiator is defined by the “local” asymmetry of the ligand and by the overall asymmetry of the particular arrangement of catalytic aggregates. Two types of process called “homosteric” and “antisteric,” which apply to the polymerization of resolvable monomers and achiral monomers of meso structure, are defined. These configurational rules have a general character and are verified in many examples of differently substituted three- or four-membered cyclic monomers (oxiranes, thiiranes, β-lactones). Stereoelective polymerization appears to be an original method for the determination of the absolute configuration of some monomers of unknown chirality.     

An orthogonal approach to multifunctional molecularly imprinted polymers

[structure: see text] An "orthogonal" approach to molecularly imprinted polymers has been demonstrated using a crown ether derived monomer that does not exhibit cross-reactivity with other functional monomers. This strategy provides multiple functional groups in the binding site of molecularly imprinted polymers (MIPs) without unproductive interactions between functional monomers. The orthogonal functional group system was shown to act cooperatively in MIPs to bind a template with higher selectivity than any of the individual functional monomers alone.     

SYNTHESIS OF POLY(SILPHENYLENE-SILOXANE) THROUGH DEHYDROCARBON POLYCONDENSATION OF 1,4-BIS(DIMETHYLSILYL)BENZENE AND DIALKOXYSILANE

Poly(silphenylene-siloxane)s had been synthesized through dehydrocarbon polycondensation of 1,4- bis(dimethylsilyl)benzene(BDSB)and dialkoxysilane.The polymer composition and structure was characterized by ~(29)Si-NMR.The influence of temperature,B(C_6F_5)_3 concentration and monomer structure on the composition and the microstructure of the copolymers were investigated.It shows that elevating reaction temperature or using substrate (R'O)_2R_2R_1Si with bulk organic group of R_1 or R_2 augments the run n...     

“Living” free radical graft copolymers I: Preparation and properties

Polymers substituted with thio groups are useful for the photochemical synthesis of graft copolymers. Such copolymers have been prepared by the initial conversion of backbone polymers containing chlorinated substituents into polymers containing diethyldithiocarbamate (TC), isopropyl xanthate (IX) or mercaptobenzothiazole (BT) functionality. The photochemical reaction of monomers with these products produced graft copolymers. A variety of halogenated polymers were investigated as starting materials for these syntheses, including poly(vinyl chloride), chlorinated polyvinyl chloride), chlorinated polyethylene, chlorobutyl rubber and neoprene. Characteristics of the grafting reactions, including “pseudo-living” behavior and tandem grafting aspects, were investigated. Glass transitions of the grafted polymers were found to vary uniformly with composition for most of the grafted products.     

ABg型单体缩聚反应的动力学分析

研究了AB_g型单体缩聚反应的动力学,导出了分子量分布函数以及数均和重均分子量.一些结果与Flory用统计方法得到的一致.数值计算结果表明,单体上B官能团越多,反应所得的超支化聚合物的分子量分布越宽;多分散性随着A基团转化率的增加而增加,且当反应接近完成时迅速增加,这个结论与Turner等的实验数据定性地一致.     

Self-Reguiating Poiycondensations. II. A Study of the Order Present in Polyamide-Hydrazides Derived from Terephthaloyl Chloride and p-Aminobenzhydrazide

The problem of chemical order of polyamide-hydrazides prepared from terephthaloyl chloride with an unsymmetrical monomer, p-aminobenzhydrazide, is discussed. An NMR method for identifying the molecular structure of species formed in the early stages of poly condensation has enabled the course of a polymerization to be followed during this time and the final degree of order to be predicted qualitatively. These studies have provided a demonstration that the structure of these polymers can be controlled to a significant degree by appropriate variations in experimental conditions. But even under the most adverse conditions usually employed, poly amide-hydrazides are found to be at least “partially ordered” copolymers. The techniques developed for this study may find application in the study of other polymer forming reactions with monomers having two functional groups with dissimilar reactivities.     

Synthesis and evaluation of cationic and cationogenic polymeric sorbents for removing surfactants from aqueous solutions

Polymers based on 2‐dimethylaminoethyl methacrylate (DMAEMA) crossslinked with ethylene glycol dimethacrylate (EGDMA) or N,N′‐methylenebisacrylamide (MBAA) have been prepared by solution‐suspension polymerization. Polymers containing ammonium groups were synthesized by quaternization of aminofunctional polymers obtained with ethyl or dodecyl bromide or by the polymerization of respective quaternized monomers. Influence of the content of DMAEMA in the polymers, nominal degree of crosslinking, length of alkyl substituent in quaternary ammonium groups as well as particle size on the sorption of anionic and nonionic surfactants from aqueous solutions has been studied.     

Self-regulating polycondensations: Ordered aromatic polyamide-esters

The polycondensation of aminophenols with diacid chlorides was examined to determine if the amide-ester polymers obtained are random or ordered. All of the evidence obtained points to the conclusion that ordered copolymers indeed are prepared and that a “self-regulating” polymerization process is operating by virtue of the considerably greater reactivity of aromatic amino groups relative to phenol groups. The first step of the reaction involves the in situ preparation of a diphenol-amide which undergoes further condensation. The diphenol-amide intermediate may be isolated or reacted in situ. In addition to the ordered polymer from a given aminophenol and a single diacid chloride, ordered copolymers from two different diacid chlorides were prepared in which the diacid moieties appear in an alternating fashion; the structure of such polymers depends on the order of addition of the diacid chlorides. Corresponding polymers also may be prepared from the preformed diphenol-amide monomers. The molecular weights of certain of the polymers were sufficient for the preparation of films which could be hot-stretched severalfold. Interfacial polycondensations gave polymers of higher inherent viscosities than did solution polymerizations when aminophenols or diphenol-amide monomers were condensed with diacid chlorides.     

Synthons as building blocks in the synthesis of liquid crystalline multiblock copolymers

Synthetic approaches which allow to insert rather long fragments with exactly definite sequence of several single structural units into polymer chains are considered and summarized. The procedure consists in preliminary formation of such sequences in a form of bifunctional “complex monomer” (synthons) which may undergo a polycondensation with other single or complex monomer to form macromolecule with definite alternation of several single monomers. These synthetic approaches were used for the synthesis of LC multi-block copolymers with definite structure of rigid block.     

Polymeres porteurs de greffons peptidiques: Polymérisation et copolymérisation de monomères styréniques parasubstitués par des oligopeptides

Polymers and copolymers with peptide pendant chains have been prepared by polymerization and copolymerization of styrene with para styryl peptide monomers terminated by a carboxylic acid or primary amine group.

Polymerizations of I and II have been initiated by AIBN, in tetrahydrofuran or N,N-dimethylformamide. For polymers with functional ends on side-chains protected by urethane functions (amino group) or ester function (acid group), polymer regeneration has been carried out by acidolysis (urethane) and basic hydrolysis (ester). The influences of monomer structure on polymerization yield and the water solubility after neutralisation, have been considered. Copolymerizations of styrene with I and II have been studied. Random copolymers, with solubility in various solvents depending on their composition, have been obtained. Reactivity ratios have been determined.     

L-glutamic acid as a versatile platform for rapid synthesis of functional polyesters via facile Passerini multicomponent polymerization

In this work, a series of polyesters with different functional side groups were successfully prepared by Passerini three-component polymerization (P-3CP) in “one-pot” from biorenewable l -glutamic acid (l -GA)-based monomers. First, the polymerization conditions including monomer feed ratios, solvents and comonomer were systematically studied using Boc-protected l -GA with adipaldehyde and tert-butyl isocyanide. Under the optimal polymerization conditions, a variety of N-substituted l -GA-based monomers as well as functional isocyanides were attempted in the P-3CP to produce polyesters with different functionalities. Moreover, it was found that after removal of pendant protecting groups, the obtained l -GA-based polyester degraded spontaneously into small molecules via 1,5-intramolecular cyclization between the pendant amine groups and the ester groups in polymer backbone. The structures and thermal properties of obtained polymers were determined by ¹H NMR, IR, SEC, MALDI-ToF-MS, DSC, and TGA measurements. Starting from biorenewable l -GA, this approach will provide a facile and straightforward route to produce functional and biodegradable polyesters, thus effectively expanding the range of biodegradable polymers.     

Synthesis of Polyamides and Polyesters Having Various Functional Groups

Polyamides and polyesters having various functional groups have been synthesized either by the polycondensation of functional monomers having a high reactivity or by the modification of unsaturated polymers by means of suitable polymer reactions. Polyamides or polyesters having hydrophilic groups such as hydroxyl group have a high affinity for moisture adsorption and are applicable to membrane uses. Photosensitive polyamides or polyesters were also prepared.