Parent Copolymer Research Articles

Polymer electrolytes based on acrylonitrile–butyl acrylate copolymers and lithium bis(trifluoromethanesulfone)imide

Novel “polymer-in-salt“ electrolytes were prepared by mixing random copolymers of acrylonitrile and butyl acrylate [poly(AN- co-BuA)] with lithium bis(trifluoromethanesulfone)imide (LiTFSI). The interaction of Li + ions and polymeric groups was investigated by DSC and IR methods; electrical properties were studied by impedance spectroscopy. The properties of the new system were compared to those of the well-known poly(ethylene oxide) (PEO)–LiTFSI polymer electrolytes. The mixtures of poly(AN- co-BuA) and LiTFSI exhibit much lower glass transition temperature T g than the parent copolymer (decrease of over 60 K for high salt content). By extrapolation of the dependence of the T g on the salt content, the value of T g for pure LiTFSI was estimated as 232 K. The decrease of T g was correlated with the increase of the decoupling index, R τ , which is proportional to the value of conductivity measured at T g. The interactions of LiTFSI with poly(AN- co-BuA) lead to high flexibility of this system; a property that is opposite to the behavior of the PEO–LiTFSI system, where interactions between the salt and polyether lead to stiffening of the polymer with increasing salt content.

Effect of Molecular Weight Distribution on Microphase-Separated Structures from Block Copolymers

The effect of molecular weight distribution on microphase-separated structures for both AB diblock and BAB triblock copolymers was investigated in comparison with that of composition distribution. Monodisperse poly(styrene-b-2-vinylpyridine) (SP) and poly(2-vinylpyridine-b-styrene-b-2-vinylpyridine) (PSP) parent block copolymers were synthesized by living anionic polymerizations whose volume ratios were all designed to be 0.5/0.5. Three parent copolymers were blended variously with both number-average molecular weight and composition kept constant but having different molecular weight distribution. Microphase-separated structures of sample films obtained by solvent-casting followed by annealing were observed by transmission electron microscopy and small-angle X-ray scattering. It has been found that both SP and PSP block copolymers show simple lamellar structures even when the molecular weight distribution is relatively wide and that lamellar domain spacing increases with increase in polydispersity index of the blend system. Furthermore, the increment for PSP triblock is larger than that for SP diblock as was the result for the study on composition distribution. The microdomain expansion can be caused by the localization of polydisperse block chains in both phases, which was commonly observed for both the composition distribution system and the molecular weight distribution system.

Adsorption of triblock copolymers and their homopolymers at laponite clay/solution interface. Role played by the copolymer nature

The adsorption thermodynamics of copolymers, based on ethylene oxide (EO) and propylene oxide (PO) units, at the laponite (RD) clay/liquid interface was determined at 298 K. The copolymer nature was tuned at molecular level by changing the hydrophilicity, the architecture and the molecular weight (Mw) keeping constant the EO/PO ratio. Polyethylene (PEGs) and polypropylene (PPGs) glycols with varying Mw and their mixture were also investigated to discriminate the role of the EO and the PO segments in the adsorption process. Enthalpies of transfer of RD, at fixed concentration, from water to the aqueous macromolecule solutions as functions of the macromolecule molality were determined. They were treated quantitatively by means of a model based on two equilibria: (1) one-to-one binding between the macromolecule and the site on the solid and (2) two-to-one binding following which one macromolecule interacts with another one adsorbed onto the solid. The good agreement between the equilibrium constants obtained from calorimetry and those determined from kinetic experiments confirmed the reliability of the experimental and theoretical approaches. Almost all of the systems investigated are highlighted by the one-to-one binding; the L35 and 10R5 systems present both equilibria. The insights provided by the thermodynamics of adsorption of their homopolymers onto RD were fruitful in obtaining detailed information on the nature of the forces involved between RD and the copolymers. The data obtained in the present work clearly evidenced that for comparable polymer Mw, PPG is more suitable in building up a steric barrier around the RD particles and, indeed, exhibits several advantages and no drawbacks. Moreover, the parent copolymers may properly functionalize the RD surface by exploiting both their high affinity to the solid surface and the ability to self-assemble onto it as L35 and 10R5 clearly showed.

Thermal and structural properties of high-energy electron irradiated poly(vinylidene fluoride-trifluoroethylene) copolymer blends

Thermal and structural properties of high-energy electron irradiated ferroelectric blends by poly(vinylidene fluoride-trifluoroethylene) 56/44 and 80/20 mol% copolymers have been investigated by thermally stimulated depolarization current (TSDC), differential scanning calorimetry (DSC) and X-ray diffraction measurements. The temperature peaks observed in TSDC spectra of the blends decrease with the irradiation dose, associating phase transitional characters of the parent copolymers. And their distribution shows the existence of two types of crystallite, which become more clear after irradiation, demonstrating that the miscibility in the crystalline region for their large compositional discrepancy (24 mol% in their VF 2 contents) in the blend. In DSC thermograms, it is found that the Curie temperature and melting temperature decrease with the dose. The ferroelectric-to-paraelectric (F–P) transition temperatures and enthalpies in the blends merge into one with the increasing of dose, which indicates a strong lattice coupling. X-ray diffraction shows some degree of mixing inside a crystal lattice due to significant changes in the F–P phase transition behavior from all-trans to trans-gauche conformation in nanometer range after irradiation.

Amphiphilic maleic acid‐containing alternating copolymers—2. Dilute solution characterization by light scattering, intrinsic viscosity, and PGSE NMR spectroscopy

AbstractThe dilute solution behavior of several alternating copolymers of maleic acid has been characterized by static and dynamic light scattering, intrinsic viscosity, and pulsed‐gradient spin‐echo NMR spectroscopy. The copolymer of maleic acid–sodium salt and isobutylene (IBMA‐Na, Mw ∼350 kg/mol) dissolves readily in concentrated aqueous salt solutions. Changes in chain dimensions with ionic strength and pH are similar to those of the lesser salt solution‐soluble poly(acrylic acid‐sodium salt). The hydrophobically modified (with n‐butyl, n‐hexyl, n‐octyl, and phenethyl amines) copolymers of maleic acid–sodium salts and isobutylene (IBMA‐NHR‐Na) show no sign of large intermolecular aggregation in 0.1 N sodium acetate (NaAc). However, the sizes of the copolymers are relatively small compared to that of the ionized parent copolymer (IBMA‐Na, Mw ∼350 kg/mol), suggesting intramolecular aggregation of the alkyl side‐chain groups along the polymer backbone. The copolymer modified with the longer chain n‐decyl, on the other hand, forms stable large intermolecular aggregates containing 33 chains/aggregate. The copolymers of maleic acid–sodium salt and styrene (SMA‐Na) appear to have no signs of aggregation, despite being a hydrophobic polyelectrolyte. The copolymer of maleic acid–sodium salt and di‐isobutylene (DIBMA‐Na) has a similar salting‐out concentration as SMA‐Na. The radius of gyration measurements by static light scattering suggest that at least some fraction of the DIBMA‐Na chains form large intermolecular aggregates. The copolymers of maleic acid–sodium salt with n‐alkenes (n‐CmMA‐Na) in 0.1 N NaAc form small intermolecular aggregates (three to five chains/aggregate). In contrast to these static light scattering results, PGSE NMR diffusion measurements for the above aggregated systems indicate only one diffusion coefficient consistent with the motion of single isolated chains. A plausible explanation for this discrepancy is that the population of the aggregates is too small to be sufficiently detected in the PGSE NMR experiment. Furthermore, it is likely that the aggregate has a larger relaxation rate than the nonaggregate, and therefore has a comparatively reduced signal in the PGSE NMR experiment. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3584–3597, 2004

Modular Synthesis of Functional Block Copolymers

AbstractSummary: The free‐radical addition of ω‐functional mercaptans to the vinyl double bonds of 1,2‐polybutadiene‐block‐poly(ethylene oxide) copolymers was used for modular synthesis of well‐defined functional block copolymers. The modification reaction proceeds smoothly and yields quantitatively functionalized block copolymers (1H NMR and FT‐IR spectroscopy) without disturbing the molecular‐weight distribution of the parent copolymer (PDI < 1.09, size exclusion chromatography).The modular synthetic pathway towards the functional block copolymers reported here.imageThe modular synthetic pathway towards the functional block copolymers reported here.

Polymeric stationary phase, based on (R,R)‐tartramide and bisphenol S, with potential chiral properties

AbstractA new polymeric stationary phase with potential chiral properties, obtained by the chemical modification of the parent copolymer of dimethacrylate esters of bisphenol S and divinylbenzene, is presented. Hydroxyl functional groups present in the copolymer chemical structure are blocked by optically active selectors of (R,R)‐tartramide derivatives. The influence of the chemical modification of the parent copolymer on its porous structure has been studied. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2566–2574, 2004

Thermal degradation of copolymers of styrene with dicarboxylic acidsI. Alternating styrene-maleic acid copolymer

An alternating styrene-maleic anhydride copolymer was hydrolysed to obtain styrene-maleic acid copolymer. The degradation of the product was studied and the thermal stability of hydrolysed copolymer compared with that of parent copolymer. It was found that alternating styrene-maleic acid copolymer degraded in three stages. FTIR spectra of heated film of copolymer as well as mass spectrometry of volatile products of the decomposition indicate that dehydration is the main reaction, which takes place at the first stage of degradation. However, the decomposition is not only the simple regeneration of the maleic anhydride units. Heating of the styrene-maleic acid copolymer to 250 °C causes an increase of its glass temperature in comparison to T g of the parent copolymer. During heating at 140 °C the hydrolysed styrene-maleic acid copolymer loses its solubility in polar solvents, presumably due to crosslinking. The volatile products of the last two stages of degradation were studied by mass spectrometry.

Maleic copolymers with pendant disinfectant and/or odorant molecules II. Thermal and thermo-oxidative behaviour

New esters of alternating maleic anhydride/styrene or vinyl acetate copolymers with thymol, eugenol, phenylethyl alcohol and citronellol, known as bioactive molecules with disinfectant and/or odorant properties, have been synthesized and characterized by conductometry and infrared spectroscopy. Their thermo-oxidative and thermal behaviour under dynamic conditions of heating were studied by means of thermogravimetry and differential scanning calorimetry. One or two thermogravimetric steps of weight loss are characteristic for the studied compounds in the 20–450°C temperature range, that are endothermic processes in DSC curves. The characteristic temperatures, weight losses, overall kinetic parameters and reaction heats were evaluated and information about physical and/or chemical processes involved, have been obtained. On the basis of these results two distinct pathways for the release of active moieties have been proposed in respect to the parent copolymer. IR spectra recorded after heating at various temperatures support the proposed mechanisms. ©

Macroporous polyamines containing cyclodextrin: Synthesis, characterization, and sorption properties

Macroporous beads containing N-vinyl-tertio-butyl carbamate (NVTBC) have been prepared by suspension copolymerization using divinylbenzene as crosslinking agent. After solvolysis, parent copolymers containing vinylamine (VA) were functionalized by β-cyclodextrin (β-CD) using the mono-tosyl derivative of β-CD as the intermediate (β-CDOTs). Several copolymers with various degrees of substitution were synthesized. Several factors (reaction time, amounts of the reactants, composition of solvent, and temperature) were studied. Characterization was achieved by crosspolarization magic angle spinning nuclear magnetic resonance spectroscopy (CPMAS NMR). The textural features (specific area and porous volume) of the beads were also determined. These insoluble macroporous copolymers containing β-CD were then used for the recovery of various organic pollutants from aqueous solutions. Some preliminary studies (time, concentration, kinetics, and β-CD content) are presented here. The results of sorption experiments show that they exhibit high sorption capacities toward substituted benzene derivatives. The mechanism of sorption is an acid-base interaction due to the amino groups of the polymer network and/or the formation of an inclusion complex due to the β-CD molecules. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1419–1427, 1998

Structure of Poly(vinyl alcohol) Microfibrils Produced by Saponification of Copoly(vinyl pivalate/vinyl acetate)

High molecular weight specimens of syndiotacticity-rich poly(vinyl alcohol) (PVA) have been prepared by saponification of copolymers of vinyl pivalate (VPi) and vinyl acetate (VAc). VPi and VAc were copolymerized using the low-temperature initiator 2,2‘-azobis(2,4-dimethylvaleronitrile) and saponified in KOH/methanol/water with vigorous stirring, i.e., under shear. The PVAs obtained had number-average degrees of polymerization in the range (5.6−16.5) × 103 and syndiotactic diad (S-diad) contents of 52.8−61.5%. The highest molecular weight and S-diad content were obtained for specimens derived from homopoly(VPi) prepared at low initiator concentration, and these parameters declined progressively with increasing VAc content in the parent copolymers. The structures of these PVAs show a consistent sharp transition between 55 and 56% S-diad content. Specimens with lower S-diad contents have shapeless morphologies, but at 56% S-diad content the polymers were fibrous, with a higher degree of crystallinity and or...

Supercritical Fractionation of A Perfluorinated Copolymer

A perfluorinated copolymer, poly(tetrafluoroethylene-co-19, 3 mol % hexafluoropropylene), is fractionated using supercritical SF6. The fractionations arc performed isothermally at 163°C using an increasing pressure profile to obtain gram-sized fractions that have molecular weight distributions that are narrower than that of the parent copolymer. The fractionation pressure is increased in increments of 34 bar from 276 to 683 bar. The parent material and the fractions are characterized using SEC and FTTR spectroscopy. The first seven samples, eluting between 276 and 552 bar, show a trend of increased molecular weight of the fraction with increasing fractionation pressure. Above 552 bar, the molecular weight of the remaining fractions decreases with increasing fractionation pressure. Although these last fractions do not differ in hexafluoropropylene content, they do differ in the type and concentration of their end groups. In particular, the fractions that eluted at pressures greater than 552 bar contain increasing amounts of carboxylic acid end groups. The strong hydrogen-bonding interactions of these end groups prevent oligomers with acid ends from eluting from the column at lower pressures, which was expected due to their lower molecular weight.

Fractionation of poly(ethylene-co-vinyl acetate) in supercritical propylene: Towards a molecular understanding of a complex macromolecule

A commercial low-density polyethylene copolymer, poly(ethylene-co-vinyl acetate) (EVA), synthesized via the high-pressure free-radical polymerization process, was fractionated with supercritical propylene by isothermal increasing pressure profiling and critical, isobaric, temperature rising elution fractionation (CITREF™). Extensive characterization of the fractions by nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC) in combination with low-angle laser light scattering (LALLS), and differential scanning calorimetry (DSC) was used to map not only the molecular-weight and chemical composition distributions of the parent copolymer, but also its short-chain branch (SCB) and long-chain branch (LCB) distributions. Fractionation by increasing pressure profiling confirmed the broad molecular-weight distribution and the narrow acetate-branch distribution expected for this random copolymer but revealed the presence of a small amount (∼ 2 wt %) of low molecular-weight amorphous species containing a high level of alkyl SCBs (80 branches/1000 C). The LCB density estimated from the Zimm-Stockmayer relationship using the GPC data monotonically increases with increasing molecular weight above 60,000 g/mol, in agreement with the kinetics of free-radical polymerization. CITREF™ was found to fractionate this copolymer by crystallinity, which is influenced by both the alkyl SCBs and the acetate branches. Up to 18% difference in total branch density (<5% in crystallinity) between EVA molecules was identified using CITREF™. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2015–2030, 1997

Supercritical-fluid fractionation of poly(ethylene-co-acrylic acid)

Poly(ethylene-co-acrylic acid) copolymers of 3.1 and 3.9 mol % acrylic acid are fractionated with supercritical propane, butane, and dimethyl ether. The fractionations are performed isothermally using increasing pressure profiling that provides gram-size fractions with molecular-weight distributions of ∼ 1.2 to 3.0 as compared to the parent copolymers which have polydispersities near 6.0. It is possible to fractionate these acid copolymers with respect to chemical composition by first using one of the poor quality solvents, propane or butane, that solubilize the nonpolar ethylene-rich oligomers and then using dimethyl ether, a very strong solvent for these acid copolymers, to solubilize the acid-rich oligomers. The performance of the SCF fractionation is directly related to the cloud-point behavior exhibited by the copolymer-solvent mixture.

Preparation of .alpha.-Phenyl Ketone-, .omega.-Carboxylate-Ended Telechelic Methyl Methacrylate Oligomers by the Ozonolysis of Regioregular Methyl Methacrylate-Phenylacetylene Copolymers

Telechelic methyl methacrylate oligomers with α-phenyl ketone and ω-carboxylic acid end groups have been prepared by the ozonolysis of statistical copolymers of methyl methacrylate and phenylacetylene. The oligomers are exclusively α-phenyl ketone- and ω-carboxylate-ended, indicating that the incorporation of phenylacetylene in the parent copolymer is regiospecific. The oligomers have number-average molecular weights ranging from 1600 to 4500 (controlled by the composition of the copolymers from which they were prepared) and polydispersities of less than 2

Supercritical fluid fractionation of copolymers based on chemical composition and molecular weight

AbstractPoly(ethylene‐co‐methyl acrylate) copolymers of 30, 40, 60, and 70 wt % acrylate in the backbone have been fractionated with supercritical (SCF) propane, propylene, butane, 1‐butene, and chlorodifluoromethane. The fractionations were performed isothermally using an increasing pressure profile that provided gram‐sized fractions with molecular weight distributions of ∼ 1.2 to 2.2 as compared to those of the parent copolymers, which were ∼ 2.6 to 3.5. If the chemical composition distribution of the copolymer is greater than ±2%, it is possible to fractionate with respect to chemical composition by chosing solvents that preferentially dissolve the nonpolar ethylene‐rich or the polar acylate‐rich oligomers. Cloud‐point curves were determined for each copolymer in the SCF solvents to provide an indication of whether the solvent would dissolve the copolymer at temperatures and pressures within the range of the fractionation apparatus. © 1993 John Wiley &amp; Sons, Inc.

Block copolymer ionomers: solution behavior of lightly sulfonated polystyrene-b-poly(tert-butylstyrene) in polar solvent

Light scattering experiments were performed to study the structure and dynamics of block polystyrene-b-poly(tert-butylstyrene) copolymers in the sodium form with a sulfonation level of 5.8 and 12.0 mol % dissolved in DMAc at 25, 45, and 60°C in the dilute-solution regime. A polyelectrolyte-like solution behavior win observed. Due to the repulsive electrostatic interactions between like charges, the scattered intensities monitored were greatly reduced in compared with those of the unmodified diblock copolymer. In particular, a characteristic bimodal relaxation mode was observed on block ionomer solutions in strong contrast to the single-exponential decay found for the parent (neutral) copolymer solutions

Incorporation of branches into the crystal lattice during the solidification of linear low density polyethylene

Two linear low density polyethylene (LLDPE) samples containing n-hexyl and iso-butyl branches have been etched with fuming nitric acid and the products of the etching analysed by 13C n.m.r. spectroscopy to determine the concentration of branches. Different weight loss behaviour was observed with the two LLDPEs; the weight of material lost during etching plateaued at 50% with a constant low crystallinity for the iso-butyl material while the n-hexyl continued to lose weight and the residue improve in crystallinity. The residual concentration of branches was 10 and 20% of the initial concentration and clearly the two types of branches were incorporated into the crystalline lattice to different extents. The parent copolymers were fractionated by degree of branching and a comparison made between the two sets of fractions to determine their melting points, degree of crystallinity and unit cell volume. In general it was concluded that more of the hexyl branches are incorporated than the iso-butyl at the same branch content, and that chain flexibility is an important parameter in determining the extent of exclusion of the branches.

Microstructure of styrene‐methacrylic acid and styrene‐acrylic acid copolymers, 5 UV absorption study of styrene‐methacrylic acid and styreneacrylic acid copolymers

AbstractUV absorption spectra of styrene‐methacrylic acid and styrene‐acrylic acid copolymers prepared in benzene solution and in emulsion were investigated. They were compared to UV spectra of derived copolymers prepared by methylation of the carboxyl groups of the parent copolymers. In the spectra of the methylated copolymers only a hypochromic effect on all peaks was observed, whereas in the spectra of the parent acid copolymers hypochromic as well as hyperchromic effects were found. They depend on the kind of acid, its content in the copolymer and on the type of the copolymer. These differences may be explained on the basis of hydrogen bonds formed between the π‐electrons of phenyl rings and carboxyl groups. It seems that the most sensitive peak to these hydrogen bonds is that at 259 nm, while the peak at 269 nm is sensitive to electronic interactions between adjacent monomeric units.

Evaluation of protein-N-(2-hydroxypropyl) methacrylamide copolymer conjugates as targetable drug-carriers. 2. Body distribution of conjugates containing transferrin, antitransferrin receptor antibody or anti-Thy 1.2 antibody and effectiveness of transferrin-containing daunomycin conjugates against mouse L1210 leukaemia in vivo

The body distribution (5 h) of protein-N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer conjugates (Mw∼-15000) was evaluated in DBA2 mice, using either the transferrin receptor, or the Thy-1.2 antigen as specific targets. Radioiodinated HPMA copolymer (25 μg), proteins (anti-Thy 1.2, monoclonal antibody B3/25 specific for the transferrin receptor, non-specific IgG, or diferric transferrin; 10 /gmg) and protein-HPMA copolymer conjugates (10 /gmg protein) were injected intraperitoneally (i.p.) or intravenously (i.v.). Administration of protein conjugates via either route resulted in an up to 4.7-fold increase in blood-associated radioactivity (compared with free protein) together with a 2-fold decrease in the rate of excretion via the kidney. However, the organ distribution of radioactivity following administration of protein-conjugates was essentially similar to that seen following administration of free protein, but generally greater than that of the parent copolymer. For example, a maximum 11-fold and 3.5-fold increase in thymus localisation of both the anti-Thy 1.2 conjugate and the transferrin conjugate was observed when compared with that of either free polymer or non-specific IgG, respectively. However, it should be noted that this thymus-localised radioactivity accounted only fora small proportion (approximately 1%) of the dose administered. Conjugates containing transferrin, B3/25 or anti-Thy 1.2 accumulated at sites of rapid cell division namely bone marrow, intestine and skin. In a preliminary experiment to assess anti-tumour activity of transferrin-containing conjugates, HPMA copolymers were synthesised to contain additionally daunomycin (DNM) bound to the copolymer via degradable (Gly-Phe-Leu-Gly) or non-degradable (Gly-Gly) peptidc spacers. These were administered (DNM, 10 mg/kg) i.p. to DBA2 mice bearing an i.p. L1210 ascites (5 X 105 cells).