Methods to improve the properties of polymer mixtures: optimizing intermolecular interactions and compatibilization

Two methods to improve the dispersion, interfacial adhesion and properties of polymer mixtures are presented. Infrared spectroscopy and optical microscopy results document that control of the spacing of interacting moieties along the polymer chain results in optimal intermolecular hydrogen bonding and improved miscibility between two polymers. Moreover, initial results indicate that this protocol also works for polymer nanocomposites. Computational and experimental results indicate that multiblock or blocky copolymers are the most effective interfacial strengtheners among linear copolymers for polymer-polymer interfaces. ADCB and neutron reflectivity experiments provide direct evidence that multiblock copolymers that have blocks that are long enough to entangle with a homopolymer are most effective at strengthening the interface. Both sets of results provide guidelines by which multi-component polymer systems can be designed with target properties.     

Mathematical Description of the Kinetics of the Macromolecular Reaction of Oxirane Groups of Polycaproamide—Polyglycidyl Methacrylate Copolymer with Diamines

The formation of amino derivatives of PCA—PGMA graft copolymers is established by chemical analysis and IR spectroscopy in their reaction with ethylenediamine and hexamethylenediamine. Mathematical processing of the experimental data using a modified quasistationary method allowed describing the kinetics of amination of PCA—PGMA graft copolymers. The proposed approach can be used for controlling heterogeneous processes in polymer systems.     

Preparation and investigation of silicon rubber containing imide-siloxane copolymers

A study has been carried out on the preparation of some modified imide-siloxane copolymers. This has been accomplished by means of addition of α,ω-dihydropoly(di-methylsiloxane)s to N,N'-diallyldiimides by hydrosilylation reaction. The copolymers were characterized by IR and NMR spectroscopy methods. Molar mass, molar mass distribution, thermal and mechanical properties of copolymers were determined. These copolymers are used as additives, mixing them in different ratios with a silicone polymer and filler to obtain imide-silicone rubbers of high temperature vulcanizing (HTV) type. Mechanical properties of the vulcanized rubbers were evaluated.     

ESR studies of the photodegradation of cellulose graft copolymers

Ultraviolet light induced free radicals in cellulose and cellulose graft copolymers were studied by means of ESR spectroscopy. At least six kinds of free radicals were formed in cellulose when the polymer was irradiated with ultraviolet light. Polystyrene and poly(methyl methacrylate) are more resistant to ultraviolet light than cellulose; however, the cellulose graft copolymers of polystyrene and poly(methyl methacrylate) were degraded by ultraviolet light. ESR studies revealed that photoinduced free radicals in cellulose graft copolymers were formed at the grafting branches of the copolymers rather than the cellulose backbone. The mechanisms of light stabilization and energy transfer reactions of cellulose and cellulose graft copolymers are discussed.     

Synthesis and Characterization of Methacrylate-Based Antibacterial Copolymers for Anticorrosive Application

Functional methacrylate polymer coatings can help retard materials from corrosion. However, the antibacterial-based anticorrosive coating of methacrylate polymer is very limited. In this paper, a functional methacrylate, namely, p-acetamidophenyl methacrylate was copolymerized with N-vinylpyrrolidone and it was characterized by Fourier transform infrared spectroscopy, ¹H and ¹³C nuclear magnetic resonance spectroscopy. Thermal analyses of copolymers were studied by thermogravimetric analysis. The polymers were tested for their in vitro antibacterial activity by well diffusion method against microbes using ampicillin as a standard. The corrosion behavior of mild steel specimens coated with different ratios of copolymers has been studied by potentiodynamic polarization and electrochemical impedance spectroscopic methods. It was showed that the copolymer-coated specimens exhibited high protection efficiency than uncoated one.     

Copolymer composition as a function of molecular weight for poly(styrene-methyl methacrylate) initiated by ethylaluminum sesquichloride

There is an increasing body of evidence showing that, for a variety of copolymers, there are significant changes in the copolymer composition over the molecular weight distribution of the polymer. In this work, we have polymerized the copolymer poly(styrene-methyl methacrylate) using ethylaluminum sesquichloride as the initiator. The copolymers produced were fractionated using a semiprep gel permeation chromatograph. The composition of the fractions was determined using infrared spectroscopy. Results show that the percent methyl methacrylate of the copolymers was higher at both the low- and high-molecular-weight regions of the polymers.     

Membrane properties of sulfonated polytriazoles with molecular branching

The incorporation of branching units in the polymer is beneficial in improving many of the polymer properties. This article deals with the synthesis of branched sulfonic acid–based copolytriazoles (PTHPSH-XX) to prepare freestanding membranes. The copolymers were synthesized by the click reaction of 1,4-bis(prop-2-ynyloxy)benzene, 1,3,5 tris[2-trifluoromethyl-4(4-azidophenyl) phenoxy]benzene (B₃), and 4,4′-diazido-2,2′-stilbene disulfonic acid disodium salt. The chemical constructions of the subsequent copolymers were established by Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. The copolymers showed high thermal stability, low water absorption, and outstanding structural robustness in their hydrated state. The presence of branching segments (B₃) in the copolymers contributed to improved peroxide radical resistance and proton conductivity (71–192 mS/cm measured at 90°C) in comparison with their linear analogs. In addition, the membranes exhibited reasonably good set of mechanical properties (TS = 71–53 MPa, YM = 2.76–2.33 GPa). The membranes exhibited phase-separated morphology in their transmission electron microscope images with ionic domains of 20–160 nm.     

Synthesis and characterization of ethylene-xylene-based polysulfide block-copolymers using the interfacial polymerization method

Copolymers of linear and aromatic polysulfide blocks are synthesized using interfacial polymerization of dichloro-xylene-based aromatic and ethylene-dichloride-based non-aromatic organic monomers. Synthesized copolymers consist of poly(ethylene sulfide) as well as ploy (xylene sulfide) blocks. Fascinating properties of linear and aromatic polysulfide species are gathered in the structure of synthesized polysulfide copolymers. Ethylene dichloride and α,α′-dichloro-p-xylene are used as the non-aromatic and aromatic organic monomers, respectively. To investigate the influences of sulfur contents in the backbone of the polymer on the thermal stability of synthesized copolymers, poly(ethylene-xylene disulfide) (PEXDS), poly(ethylene-xylene trisulfide) (PEXTRS) and poly(ethylene-xylene tetrasulfide) (PEXTS) copolymers are synthesized using, respectively, sodium disulfide, sodium trisulfide and sodium tetrasulfide, as aqueous monomers. Compared to both linear and nonlinear homopolymers, synthesized copolymers exhibit improved thermal stability. Moreover, the thermal degradation temperatures of synthesized copolymers improve by decreasing the number of sulfur atoms in the backbone of copolymers. These results reveal that thermal degradation of polysulfide copolymers can be tailored by controlling the polysulfide chain’s sulfur contents. Structural characteristics of synthesized polysulfide copolymers are also investigated using Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy and X-ray diffraction analysis.     

Surface modification of ethylene copolymers moulded against different mould surfaces-1. Surface enrichment by functional groups

A polymer surface chemical composition can be changed by the influence of different environments. Results presented from this study show that the surface of the mould influences the outermost polymer surface by enriching it with specific functional groups. This was done by moulding random copolymers against polymer films with low and high surface energies. The values presented are interpreted in terms of differences in surface energy between the mould surface and the copolymer. The random copolymers used were poly(ethylene-co-vinylacetate) (EVA) and poly(ethylene-co-acrylic acid) (EAA), both with a different comonomer content. The copolymers were moulded in contact with mould surfaces made of polymer films which were perfluorinated ethylene propylene copolymer (FEP), poly(tetrafluoroethylene) (PTFE), and poly(ethylene terephthalate) (PET). The resultant surfaces were characterized by X-ray photoelectron spectroscopy (XPS or ESCA) and contact angle measurements The surface content of acrylic acid functional groups increased in the case of EAA copolymer moulded against PET, and decreased when moulded against FEP as compared to the bulk concentration. EVA copolymers were found to be enriched in acetate groups when moulded against FEP and deficient when moulded against PET. The contact angle measurements together with the XPS measurements showed significant differences between materials moulded in contact with low and high energy surfaces. A low molecular weight additive (an internal release agent), in an EVA copolymer, was found to be enriched at the moulded polymer surface when a PET film was used as mould surface. A material transfer was also found to occur from the solid polymer films to the moulded polymer surface.     

Photodegradation of ethylene–propylene copolymer and ethylene–propylene–ethylidenenorbornene terpolymer

Significant progress has been made in recent years regarding the photooxidation of olefin copolymers, but questions still remain. This paper reviews the progress and probes the photooxidative chemistry of ethylene–propylene (EP) and ethylene/propylene/diene monomer (EPDM) copolymers. Both stabilized and unstabilized polymer plaques were irradiated in a xenon are and the surface chemistry followed using infra-red spectroscopy. Model compounds were used to help elucidate the chemistry caused by unique structural features present in the copolymers. Volatile products evolved during photooxidation were determined giving valuable insight into the degradation chemistry.