Modification of montmorillonite by cationic polyesters

Novel types of polyester hydrochlorides and polyesters were synthesized from N-octyl- or N-methyldiethanolamine and organic acid chlorides with varying chain length. Their structure, molar masses and glass transition temperatures were determined. Montmorillonite (MMT) was modified by cation exchange with the polyester hydrochlorides. The basal spacing was not significantly influenced by the length of organic acid chain but increased with the length of the alkyl group attached to nitrogen atom. Cation ratio of MMT and hydrochloride must have been at least 1:3 for quantitative cation exchange, indicating that only a part of polycation chain adheres to MMT surface. Hydrophobicity and organic content increased with increased exchange ratio, reaching approximately constant levels at ratios above 1:3.     

The synthesis of a physically crosslinked NVP based hydrogel

Complexes of polyvinyl pyrrolidinone–polyacrylic acid (PVP–PAA) were prepared by photopolymerisation from a mixture of the monomers NVP and AA. The complexes were characterised by means of differential scanning calorimetry, Fourier transform infrared spectroscopy (Ftir), potentiometric titration, swelling studies and gel permeation chromatography. The Ftir spectra of PVP–PAA copolymer complexes indicates hydrogen bonding between the carbonyl group in the PVP and the carboxylic acid group in the PAA moiety. As the percentage of AA increases in the copolymer there is evidence of increased intermolecular hydrogen bonding between the carboxylic acid groups of the AA segments. Swelling of the PVP–PAA complex in a higher pH medium is significantly different from results in low pH solutions. The critical pH range was found to be between 4.07 and 4.49. Above a pH of 4.49, there is a progressive break up of the polymer chain due to a reduction in the amount of intermolecular hydrogen bonding. There is also a significant increase in the solubility of the copolymer complex at higher pHs. The low solubility of the copolymer at low pH may make the complex suitable for gastric drug delivery systems.     

Syntheses and photoluminescence properties of UV photocrosslinkable polyesters based on fluorene

Suppression of the green emission for polyfluorene has been widely investigated and various methods have been explored. In the present work, the photocrosslinkable copolyesters based on ferulic acid and 9-hydroxy-9-fluorene-carboxylic acid with different monomer feed molar ratios were synthesized and photocrosslinking reactions were employed to make the copolyesters crosslinked. All the photoluminescence spectra of the polyesters prior to photocrosslinking peaked at 418 nm in chloroform with quantum efficiencies more than 0.65. After crosslinking, copolyester P2 showed better thermo-stability of photoluminescence than the conjugated poly(9,9-dihexylfluorene). This indicated that the crosslinking architecture could suppress the chain aggregation, thus improving the purity of blue emission.     

对苯二甲酸和聚酯废水综合处理探讨

对苯二甲酸和聚酸装置废水的处理是制约化纤厂环保达标的关键。作者通过对该废水的水质分析,物化与生化降解机理的探讨,来优化废水处理工艺,为同类装置提供一定的借鉴作用。     

Enzymatic hydrolysis of polyester based coatings

The potential of two hydrolytic enzymes, namely a lipase from Thermomyces lanuginosus (TlL) and a cutinase from Humicola insolens (HiC) for hydrolysis of the phthalic acid backbone based polyester coatings was assessed. Two phthalic acid/trimethylolpropane based model substrates resembling the structure of the polyester backbone of coatings were synthesized. Out of both enzymes, only the cutinase was able to hydrolyze both model substrates while the larger substrate was hydrolyzed at a lower rate. The cutinase was also able to hydrolyze a coating (alkyd resin) both in suspension and as dried film. LC–MS analysis of the hydrolysis products released from the coating revealed the presence of oleic acid, its monoglyceride, phthalic acid and 2-((3-((2-((2,3-dihydroxypropoxy)carbonyl)benzoyl)oxy)-2-hydroxypropoxy)carbonyl)benzoic acid. These results indicate that the enzyme was able to hydrolyze the polyester backbone as well as to release fatty acid side chains. Consequently, enzymatic hydrolysis has a potential for the removal of coatings, their recycling or their functionalization.     

Polymerization of olefins with bulky substituents. 1. Homo- and copolymerization of 3-(1-adamantyl)propene

The use of bulky substituents like adamantane has been shown in the past to influence the glass transition temperatures of polymers significantly. In this paper the synthesis and homopolymerization of the monomer 3-(1-adamantyl) propene is described, as well as the copolymerization of this monomer with ethene, propene, 1-pentene, 4-methyl-1-pentene, 1-hexene and 1-octene. The resultant copolymers proved to be largely insoluble in organic solvents. It was also demonstrated that the presence of the bulky methyladamantyl side group influenced the glass transition temperatures of the copolymers in comparison with the corresponding homopolymers.     

Kinetics of surface grafting on polyisoprene latexes by reaction calorimetry

The two-component redox-initiation system, cumene hydroperoxide (CHP) and tetraethylene pentamine (TEPA), was used to polymerize dimethylaminoethyl methacrylate (DMAEMA) in the presence of synthetic polyisoprene latexes. The modified latex particles are postulated to possess a ‘hairy layer’ of surface-grafted poly(DMAEMA) chains formed via an abstraction reaction between cumyloxy radicals and the isoprene moieties present in the seed polymer. The modified latexes exhibited enhanced colloidal stability to low pH, and dynamic light scattering showed that the apparent particle size was sensitive to pH. The rate of polymerization was followed by reaction calorimetry. No steady-state polymerization was observed, with a continual increase in the number of propagating chains at all initiator feed rates investigated. The data for particle size and colloidal stability, together with the calorimetric data, are consistent with radical production at the particle surface, and with abstraction near the interface being a rare event. Further, there is evidence that radical production by the redox couple is relatively slow. While this ‘topology-controlled’ reaction is responsible for the formation of the hairy layer and latex stability, the dominant polymerization process appears to be the formation of ungrafted poly(DMAEMA) in the water phase.     

Unsaturated polyesters. II. Structure and properties of polyester resins based on cinnamylsuccinic acid

Unsaturated Polyester resins were prepared by the reaction of cinnamylsuccinic acid with saturated diols, namely, ethylene, diethylene, propylene, dipropylene, tetramethylene, and hexamethylene glycols, and the unsaturated diols, namely, 1,4-butene- and 1,4-butynediols. All the polyester resins obtained have been characterized and were found to cure with styrene, with relatively low conversions. The properties of the cured polyesters in the form of films were determined. IR and ¹H-NMR spectroscopy were used for both qualitative and quantitative analyses of the polyesters and their hydrolyzate products, after curing with styrene.     

Induction of chirality into a fully sulfonated poly(methoxyaniline) via acid-base interactions with chiral amines

A wide range of chiral amines and amino alcohols associate with poly(2-methoxyaniline-5-sulfonic acid) (PMAS) in aqueous solution, from which optically active PMAS·(amine) films can be cast. The chiral induction is believed to be initiated by acid-base interactions with “free” sulfonic acid groups on the PMAS chains. Chiral amine:PMAS dimer molar ratios as low as 1:4 give PMAS·(amine) films with similar optical activity to those cast from 1:1 molar mixtures, indicating that only one in four of the “free” sulfonate groups on the PMAS chains need to be electrostatically bound by chiral ammonium ions to achieve optimal chiral induction. Circular dichroism studies show that the enantiomeric amines (R)-(+)- and (S)-(−)-1-phenylethylamine induce the opposite helical hands for the supermolecular assemblies of PMAS chains. However, there is no clear correlation between the sign of the CD signals for the PMAS·(amine) films and the configuration of structurally diverse amines.     

Unsaturated polyesters based on terephthalic acid: 4. Sequence distribution of crosslinks in styrene cured resins

The sequence distribution of the styrene crosslinks in a cured polyester formed from propylene glycol, terephthalic acid and maleic anhydride has been studied by ¹³C nuclear magnetic resonance and infrared spectroscopy. The n.m.r. method involved the degradation of the crosslinked polyester into a copolymer of styrene and fumaric acid and the interpretation of the peaks in the ¹³C spectrum, which arise from the quaternary phenyl carbon atoms in sequences of styrene units, by considering the ¹³C spectra of copolymer standards of styrene and diethyl fumarate. The crosslinking process was monitored directly by infra-red spectroscopy, and the distribution of sequence lengths of styrene units was then estimated by considering that crosslinking may be interpreted by a statistical treatment of copolymerization. Values of mol fractions of styrene units in sequences of monads, diads and triads determined by ¹³C n.m.r. and infra-red spectroscopy were in fair agreement.     

Study of performance properties of itaconic acid based acrylic-modified polyester for industrial baking finishes

Itaconic acid based unsaturated polyesters have been synthesized followed by their co-polymerization with commonly used acrylic monomers. Series of such acrylic-modified polyesters have been prepared and examined their physical and performance characteristics. Apart from determining various physico-chemical characteristics, these resins were also characterized for their molecular weight distribution and grafting of acrylic on polyester using gel permeation chromatography (GPC) and FT-IR techniques respectively. The performance of cured film and the effect on cross-linking density of the synthesized acrylic-modified polyesters were investigated through dynamic mechanical analyzer (DMA) using melamine formaldehyde resin as a cross-linker at elevated temperature. The resultant polymeric film showed excellent hardness, flexibility, impact resistance, adhesion, and cupping with improved weathering resistance over non-acrylated polyester.     

Synthesis and cross-linking of polyisoprene latexes

Seeded and ab initio emulsion polymerizations of isoprene using redox initiation systems were investigated and suitable reaction conditions determined to prepare polyisoprene latexes with minimal cross-linking. Polymerizations initiated with the potassium persulfate/sodium bisulfite (KPS/SBS) redox couple had a significant inhibition period and low yield. Polymerizations initiated with the tert-butyl hydroperoxide/tetraethylene-pentamine redox couple showed reasonable yields and no apparent inhibition. It is postulated that the lipophilic nature of the t-butyl group plays a favorable role in the entry of hydroperoxide-initiated oligomeric radicals, while persulfate-initiated radicals are more likely to undergo aqueous phase termination before entry. The cross-linking reaction by benzoyl peroxide (BPO) at 70 °C was investigated using this lightly cross-linked polyisoprene latex. ¹H NMR and gel permeation chromatography results were consistent with a reaction mechanism in which the radicals formed by the decomposition of BPO react exclusively with polyisoprene to abstract a hydrogen atom, and the resulting radicals react by termination to form cross-links. No loss of double bonds was found, suggesting that radical formation is overwhelmingly achieved by hydrogen abstraction and cross-linking occurs by termination between two radicals. Cross-linking was accompanied by chain scission, which was observed only at the beginning of the reaction. At low weight-fractions of polymer, the rate of cross-linking was dependent on the concentrations of BPO and abstractable hydrogens in a manner consistent with the postulated mechanism.     

Purple red and luminescent polyiminoarylenes containing the 1,4-diketo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DPP) chromophore

New DPP-containing polyiminoarylenes were prepared from 1,4-diketo-2,5-dihexyl-3,6-di(4′-bromophenyl)pyrrolo[3,4-c]pyrrole and various arylamine derivatives using palladium-catalyzed amination reactions. The arylamine comonomers were aniline (ANI), t-butylaniline (TBA), 2-aminoanthracene (AAN), 1-aminopyrene (APY) and N,N′-diphenyl-p-phenylenediamine (PDA). Purple red polymers with good solubility in common organic solvents and molecular weights between 4.4 and 35.8 kDa were obtained. Polymer solutions were readily fluorescent with quantum yields between 19 and 62%, while solution-cast films only showed a weak fluorescence. All polymers exhibit low band gaps of approximately 1.9 eV. Cyclovoltammetric studies indicate quasireversible oxidation for polymers with TBA, APY and PDA as comonomer units, and quasireversible reduction for the polymer with AAN comonomer unit. Polymers with APY and PDA comonomer units are electrochromic and can be switched between red in the neutral and greenish grey in the oxidized state.     

Unsaturated polyesters based on terephthalic acid: 2. Quantitative characterization of prepolymers by proton magnetic resonance spectroscopy

Integrated proton magnetic resonance spectra have been obtained for poly(propylene terephthalate) prepolymers prepared by the polyesterification of terephthalic acid with excess propylene glycol. From the peaks for the phenyl hydrogens and the methyl hydrogens, the molecular weight of the terephthalate-based components of the prepolymer is determined. The procedure may be extended to the determination of the molecular weight of all components, including excess propylene glycol. Methods for determining the concentration of excess propylene glycol and the quantity of propylene glycol lost during polyesterification are also presented.     

Synthesis and applications of unsaturated polyester resins based on PET waste

Three types of unsaturated polyester resins were synthesized from the glycolysis of polyethylene terephthalate (PET) plastic waste, considering environment, cost and properties for their applications. These synthesized unsaturated polyester resins could be used for various construction processes and materials such as no dig pipelining (NDR-1), pultrusion (PLR-1) and polymer concrete (PCR-1). PET was taken from common soft-drink bottles, and ethylene glycol (EG), diethylene glycol (DEG) and MPdiol glycol mixtures were used for the depolymerization at molar ratios. The glycolyzed PET 1 ^st products (oligomers) were reacted with maleic anhydride, phthalic anhydride and dicyclopentadiene (DCPD) (especially for polymer concrete) to form unsaturated polyester resins with mixed styrene. The lab scale (1–5 kg) and pilot plant scale-up tests (200 kg) were experimented to evaluate the processing characteristics, viscosity, acid number and curing behaviors. The main properties such as hardness, flexural strength, tensile strength, heat distortion temperature, elongation, and chemical resistance were determined based on the various uses of the three resins. Furthermore, the applicability and the properties of these developed resins were verified through many real application tests.     

聚对羟基苯甲酸侧链液晶高分子的合成与表征

合成了对羟基苯甲酸二聚体，四聚体，并分别接枝到苯乙烯－马来酸酐无规共聚物（SMA）上，得到侧链工度均匀的液晶高分子；同时在N，N'－二环己基碳二亚胺催化下采用溶液缩聚法制备了SMA接枝聚对羟基苯侧链液晶高分子。用FT-IR,DSC，偏光显同镜等方法表征了产物的结构作性质，讨论了液晶侧链对聚合物形态和热性质的影响。     

First-principles calculation of particle formation in emulsion polymerization: pseudo-bulk systems

Kinetic behavior in emulsion polymerization can be conveniently assigned as either ‘zero-one’ or ‘pseudo-bulk’. Sufficiently small particles in emulsion polymerizations obey zero-one kinetics, where entry of a radical into a particle which contains a growing radical leads to instantaneous termination. Pseudo-bulk kinetics applies to particles in which more than one free radical can co-exist for a significant period; while this is commonly applicable to large particles for any monomer, it also applies to very small particles for monomers which propagate very rapidly, such as acrylates. A methodology is developed to enable particle sizes and rates to be calculated for systems in which pseudo-bulk kinetics are important during particle formation. This takes account of all significant reactions involving radical species in the water and particle phases, including the chain-length dependence of the termination rate coefficient. A ‘cross-over radius’ r_co is used to describe the particle size where termination of radicals within the particles is no longer instantaneous. The model is applied to the emulsion polymerization of butyl acrylate. All parameters are available from the literature, except for r_co and k_p¹, the rate coefficient for propagation of a monomeric radical formed from transfer. These were determined from experiments on seeded emulsion polymerizations of this monomer, involving the steady-state rate with chemical initiator and non-steady-state rate in a system initiated by γ radiolysis, after removal from the radiation source (‘relaxation’ mode). Particle sizes and rates in unseeded butyl acrylate emulsion polymerizations at 50 °C, over a range of concentrations of persulfate as initiator and sodium dodecyl sulfate as surfactant, are predicted by the model with acceptable accuracy.