Study of the miscibility of poly(vinyl pyridines) with poly(vinyl acetate), poly(vinyl alcohol) and their copolymers

Miscibility of poly(4-vinyl pyridine) (P4VP) and poly(2-vinyl pyridine) (P2VP) with poly(viny acetate) (PVAc), poly(vinyl alcohol) PVA and poly(vinyl acetate-co-alcohol) (ACA copolymers) has been investigated over a wide composition range. Differentiaal scanning calorimetry (DSC) results indicate that P2VP is immiscible with PVAC, PVA, and their copolymers over the whole composition range. In turn, P4VP appears to be immiscible with PVAC and PVA, but miscible with some ACA copolymers in certain range of composition. The P4VP-ACA phase diagram for different copolymer compositions has been determined. The variation of the glass transition temperature with composition for miscible mixtures was found to follow the Gordon-Taylor equation, with the parameter κ dependent upon copolymer composition. FTIR analysis of blends reveal the existence of specific interactions via hydrogen bonding between hydroxyl groups and the nitrogen of the pyridinic ring, which appear to be decisive for miscibility. © 1994 John Wiley & Sons, Inc.     

Molecular weight control in polycondensation of hydroxyl diesters with hexamethylenediamine by polymer matrices

Polycondensation reactions of hydroxyl diesters such as dimethyl tartrate (DMT) and diethyl mucate (DEM) with hexamethylenediamine (HMD) were carried out in the presence of poly(vinyl pyridine) (P-VPy) and its copolymers with styrene of different compositions as matrix polymers in order to investigate the difference in interaction forces with monomers or the resulting polyamides owing to hydrogen bonding. It was found that matrix effects of poly(4-vinyl pyridine) (P-4VPy) on the rate enhancement and solution viscosity of the resulting polyamide became more pronounced with decreasing solvent polarity. This result suggests that the matrix effects of P-4VPy on polycondensation are due to hydrogen bonding interactions between hydroxyl diesters and P-4VPy. The addition of P-4VPy increased the molecular weight of the resulting polyamide to a higher extent than poly(2-vinyl pyridine) (P-2VPy), and the molecular weight of the resulting polyamide could be controlled according to the molecular weight of P-4VPy. Copolymer composition of 4-vinyl pyridine–styrene (4VPy/St) copolymers as matrix polymers also affected the molecular weight of the polyamide, which increased with increasing P-4VPy unit contents in the copolymers.     

Antibacterial activities of polystyrene-block-poly(4-vinyl pyridine) and poly(styrene-random-4-vinyl pyridine)

Styrene was polymerized in the presence of benzoyl peroxide (BPO) and 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) to yield polystyrene-TEMPO (PS-TEMPO) macroinitiator. The PS-TEMPO macroinitiator with different molecular weight was reacted with 4-vinyl pyridine (4-VP) to synthesize polystyrene-block-poly(4-vinyl pyridine) (PS-b-PVP), which was then quaternized with n-octyl iodide. Antibacterial activity of the quaternized copolymers was assessed against a gram negative bacterium (Pseudomonas aeruginosa) and a gram positive one (Staphylococcus aureus) by using the shake flask test method, and the results were compared with those of poly(styrene-random-4-vinyl pyridine) (P(ST-r--VP)). The quaternized copolymers inhibited greatly the growth of the bacteria, and PS-b-PVP was more active than P(ST-r-VP), which was ascribed to the fact that the content of quaternized 4-VP units on the surface of the particles of the former copolymer was higher than that corresponding to the latter one.     

改性酚氧树脂/聚(甲基丙烯酸丁酯-co-4-乙烯基吡啶)共混物的相容-络合行为和表面表征

合成了一系列不同4-乙烯基吡啶含量的聚(甲基丙烯酸丁酯-co-4-乙烯基吡啶)(BVPy)共聚物,并对酚氧树脂(Phenoxy)的仲羟基进行了不同乙酰化程度的改性.用粘度法和激光光散射(LLS)研究了BVPy/改性Phenoxy共混物在溶液中的络合行为对氢键相互作用基团密度的依赖性,并用DSC研究了共混体系在本体中的相容性.将粘度法及LLS的结果结合起来,得到了改性Phenoxy/BVPy共混体系的不相容-相容-络合转变相图.在此基础上,用XPS初步考察了共混物的相容性对其表面组成的影响.结果表明,大分子间的络合相互作用可抑制共混物的表面富集.     

A FOURIER TRANSFORM INFRARED SPECTROSCOPIC STUDY OF THE REACTION BETWEEN POLY (VINYL PYRIDINE)S AND EPOXY COMPOUNDS

Chemical reactions between poly (vinyl pyridine)s and 1, 4-butanediol diglycidyl ether and other epoxy compounds were studied by Fourier transform infrared spectroscopy and other techniques. The epoxy group was found to react with the pyridine side group of poly (4-vinyl pyridine), forming crosslinked networks which contain cyclic amide structures. The reaction was also observed in the interracial region of poly(vinyl pyridine) and γ-glycidoxy propyl trimethoxysilane hydrolyzate (γ-GPS) coatings on PET fiber substrates. Poly(2-vinyi pyridine) does not show the same reaction.     

Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation

Cyclic 6-membered aromatic compounds such as benzene and azabenzenes (pyridine, pyridazine, and pyrazine) are known to be light-sensitive, affording, in particular, the Dewar benzene type of intermediates. Pyridine is known to provide the only Dewar pyridine intermediate that undergoes reversible ring-opening. We found that irradiation of photosensitive gels prepared from poly(4-vinyl pyridine) and pyridine at 254 or 312 nm leads to pyridine ring-opening and subsequent formation of 5-amino-2,4-pentadienals. We show that this light-induced process is only partially reversible, and that the photogenerated aminoaldehyde and aminoaldehyde-pending groups undergo self-condensation to produce cross-linked, conjugated oligomers that absorb light in the visible spectrum up to the near-infrared range. Such a sequence of chemical reactions results in the formation of gel with two distinct morphologies: spheres and fiber-like matrices. To gain deeper insight into this process, we prepared poly(4-vinyl pyridine) with low molecular weight (about 2000 g/mol) and monitored the respective changes in absorption, fluorescence, ¹H-NMR spectra, and electrical conductivity. The conductivity of the polymer gel upon irradiation changes from ionic to electronic, indicative of a conjugated molecular wire behavior. Quantum mechanical calculations confirmed the feasibility of the proposed polycondensation process. This new polyacetylene analog has potential in thermal energy-harvesting and sensor applications.     

Enthalpy relaxations in polymer blends and block copolymers: Influence of domain size

It is now well known that enthalpy relaxation measurements can be used to establish polymer-polymer blend phase behavior when the glass transition temperatures of the two polymers are virtually coincident. In the most simple cases, the aging kinetics of an immiscible blend will be representative of the pure polymers superimposed upon each other. However, in many cases the situation is more complicated because of the presence of interface material. In this paper the relation between enthalpy recovery peak separation, domain size and interface thickness is considered. The discussion is based on relaxation experiments involving di-block copolymers of styrene and 2-vinyl pyridine, blends of polystyrene and poly(2-vinyl pyridine) and blends of poly(vinyl chloride) and poly(isopropyl methacrylate). If the amount of material in the interface is too large due to either a small average domain size or a thick interface no peak separation will occur. The first situation is found for the microphase separated block copolymer system whereas the second possibility occurs for blends of polymers which are on the verge of miscibility like poly(vinyl chloride) and poly(isopropyl methacrylate).Presented in part at the Sixth International Seminar on Polymer Physics Relaxation in Polymers, Gomadingen, October 3–8, 1988, F.R.G.     

Highly protein-resistant coatings from well-defined diblock copolymers containing sulfobetaines

Three well-defined diblock copolymers of poly(sulfobetaine methacrylate) [poly(SBMA)] and poly(propylene oxide) (PPO) were synthesized by the sequential addition of SBMA monomer to fixed amounts of PPO using an atom transfer radical polymerization method and varying poly(SBMA) lengths. These copolymers were characterized by 1H NMR and aqueous gel permeation chromatography. These copolymers were physically adsorbed onto a surface plasmon resonance (SPR) sensor surface covered by methyl-terminated self-assembled monolayers, followed by the in situ evaluation of protein adsorption on the adsorbed copolymers. It is found that the behavior of the protein adsorption depends on the molecular weight of the copolymers. Results show that the diblock copolymers containing poly(SBMA) can be highly protein resistant when surface SBMA densities are well controlled. Thus, copolymers containing zwitterionic groups are ideal for resisting protein adsorption when the surface density of zwitterionic groups is controlled.     

Stimuli-responsive surfaces using polyampholyte polymer brushes prepared via atom transfer radical polymerization

The synthesis of AB diblock copolymer polyampholyte polymer brushes of the type Si/SiO2//poly(acrylic acid-b-vinyl pyridine) prepared using atom transfer radical polymerization is reported. Both 2- and 4-vinyl pyridine have been used. The diblock polyampholyte polymer brushes demonstrate stimuli-responsive behavior with respect to pH, showing both polyelectrolyte and polyampholyte effects. Furthermore, we have quaternized the 4-vinyl pyridine segments to form a mixed weak/strong, or annealed/quenched, polyelectrolyte system. The quaternized polymer brush exhibits different pH-responsive behavior, with decreasing film thickness being observed with increasing pH.     

Novel approaches for the preparation of silica-based zwitterionic hybrid copolymers

Two novel routes for the preparation of silica-based zwitterionic hybrid copolymers were proposed. A series of zwitterionic hybrid copolymers were prepared by the sulfonation of phenyl groups and the quaternary amination of tertiary amine groups alternately. Both FT-IR and ¹H NMR spectra confirm the step products. TGA and DrTGA analyses indicate that the thermal stability of these zwitterionic hybrid copolymers is higher than 400 °C. The determination of sulfonation degree reveals that the zwitterionic hybrid copolymer (c) from sulfonation-quarteramination (Route I) has the minimal value; meanwhile the anion-exchange capacity exhibits that the zwitterionic hybrid copolymer (e) from quarteramination-sulfonation (Route II) has the minimal value. These findings demonstrate the impact of electrostatic effect on the charge content of ionic groups. MALDI-TOF mass spectra exhibit that the decrease in the stability of the charged hybrid copolymers can be ascribed to the electrostatic effect between the molecular chains. The surface SEM images demonstrate that the surface of zwitterionic hybrid copolymer (e) from quarteramination-sulfonation (Route II) has some aggregated particles and form clusters regions in the hybrid matrix, which can also be attributed to the ionic interactions between those charged groups.     

IRMPD spectra of Gly.NH4 + and proton-bound betaine dimer: evidence for the smallest gas phase zwitterionic structures

Zwitterionic structures exist extensively in biological systems and the electric field resulting from zwitterion formation is the driving force for determination of the properties, function and activity of biological molecules, such as amino acids, peptides and proteins. It is of considerable interest and import to investigate the stabilization of zwitterionic structures in the gas phase. Infrared multiple photon dissociation (IRMPD) spectroscopy is a very powerful and sensitive technique, which may elucidate clearly the structures of both ions and ionic clusters in the gas phase, since it provides IR vibrational fingerprint information. The structures of the clusters of glycine and ammonium ion and of the betaine proton-bound homodimer have been investigated using IRMPD spectroscopy, in combination with electronic structure calculations. The experimental and calculated results indicate that zwitterionic structure of glycine may be effectively stabilized by an ammonium ion. This is the smallest zwitterionic structure of an amino acid to be demonstrated in the gas phase. On the basis of the experimental IRMPD and calculated results, it is very clear that a zwitterionic structure exists in the proton-bound betaine dimer. The proton is bound to one of the carboxylate oxygens of betaine, rather than being equally shared. Investigations of zwitterionic structures in the isolated state are essential for an understanding of the intrinsic characteristics of zwitterions and salt bridge interactions in biological systems.     

Polyvinyl pyridines as flocculating agents

Summary High molecular weight poly 2- and 4-vinyl pyridines were synthesized by ionic polymerisation and their flocculation efficiency tested against kaolin and silica dispersions at pH 3. Low additions of the polymers, around 3 parts per 10₃ parts solid, destabilize the dispersions and clarify silica dispersions to a remarkable extent; however, over-addition of polymer leads to partial restabilization. The flocculation efficiency improves with increase of solids content, especially with clay dispersions. Flocculation efficiency increases with polymer molecular weight, especially over the lower part of the range covered, but is relatively independent of pH in the range 2–4. Quaternization of poly(4-vinyl pyridine) with bromobutane produces a good flocculant for aqueous silica dispersions in which the degree of restabilization on over-dosing depends on the KCI content. TheN-oxide derivatives of the vinyl pyridine polymers do not affect the colloidal stability of silica dispersions. The observations are interpreted in terms of bridging flocculation by the cationic polymer molecules between anionic surface sites on the solid particles.     

Poly(oxyethylene methacrylate)–poly(4-vinyl pyridine) comb-like polymer electrolytes for solid-state dye-sensitized solar cells

Poly(oxyethylene methacrylate)–poly(4-vinyl pyridine) (POEM–P4VP) comb-like copolymers with 3:7, 5:5, and 6:4 wt ratio were synthesized via atom transfer radical polymerization and confirmed by ¹H-NMR and FT-IR spectroscopy. The copolymers were quaternized with 1-iodopropane to convert the pyridine groups into pyridinium ions, i.e., POEM–qP4VP. Transmission electron microscopy showed that strongly segregated microphase separation in POEM–P4VP was less prominent upon quaternization due to interactions between the ether oxygens of POEM and the quaternized pyridine groups of qP4VP, as confirmed by FT-IR spectroscopy. The energy conversion efficiencies of dye-sensitized solar cells (DSSCs) with quaternized polymer electrolytes were always greater than those with pristine electrolytes due to greater ionic conductivity and concentrations of free iodide ions. The maximum energy conversion efficiency of a DSSC employing POEM–qP4VP electrolyte reached 3.0% at 100 mW/cm² when a 6:4 wt.% of POEM–qP4VP was used.     

Supramolecular PS-P4VP diblock copolymer thin films slowly dip-coated from chloroform solutions

This contribution shows the strong influence of using chloroform instead of THF on the characteristics of thin films of supramolecular block copolymers of poly(styrene-b-4-vinyl pyridine) dip-coated in the so-called "capillarity" regime from solutions containing 1-naphthol or 1-naphthoic acid.The small molecule content in the dip-coated films was investigated by infrared spectroscopy and the film morphology by atomic force microscopy.It was found that the small molecule content in the films is constant with dip-coating rate in the range investigated,but it is higher for 1-naphthoic acid than for 1-naphthol.The main morphology observed was in the form of "islands" and "holes",which is typical of flat-on lamellae.These findings are related to hydrogen-bonding between the small molecule and pyridine being conserved in chloroform and to the good solubility of both blocks in this solvent,with differences between the two small molecules related to their differing H-bond strengths.These findings contrast strongly with what was observed previously using THF as a solvent,for which the SM content increases with dip-coating rate and the morphologies are mainly spherical and cylindrical in the same parameter range.     

Unusual behaviour of crosslinked and linear forms of a zwitterionic polymer in aqueous alkali

Novel findings are reported on hydrogels and aqueous solutions of the zwitterionic polymer, poly[1‐(3‐sulfopropyl)‐2‐vinylpyridinium‐betaine]. In aqueous media of high pH: (a) the chemically crosslinked polymer develops a reddish‐brown coloration followed by physical disintegration and dissolution, and (b) the corresponding linear polymer exhibits the same coloration and undergoes a reduction in molecular weight, solution viscosity and T_g. These finding lie in sharp contrast to normal behaviour exhibited in neutral and acidic aqueous media. Although an unequivocal definitive mechanism is not known, a possible explanation consistent with the experimental observations is suggested.     

Etude de la nature des especes ioniques intervenant au cours de la polymerisation anionique de la vinyl-4 pyridine

Initiation of anionic polymerization of 4-vinyl-pyridine (4-VP) in tetrahydrofuran solution, using organo-metallic compounds of Na and K, involves the same type of side reactions as the polymerization of 2-vinyl pyridine (2-VP). The living polymers of 2- and 4-VP have similar u.v. spectra. The values of the dissociation constants of ionic species of 2- and 4-VP are similar when the chain [poly(styrene-b vinyl-4 pyridine)] contains one 4-VP unit (K_n ≈ 10^?9). But when the size of 4-VP block increases, the conductivity goes up to the value observed for living polystyrene (K_D ≈ 10^?7). This phenomenon could be due to a solvation of the counter-ion by the poly 4-vinyl pyridine chain, acting as a polydentate complexing agent.     

Synthesis of polymers having zwitterionic structure via the radical polymerization of 4-vinylphenyl isothiocyanate/cyclic amidine adduct

Polymers having a zwitterionic pendant group have found a wide range of applications such as fungicides, fire-retardants, lubricating oil additives, emulsifiers, cryoprotectants, and electronic materials. Their properties depend not only on the polymer main chains but also on the zwitterionic structures. In this article, the synthesis of novel polymers having zwitterionic structures is described. A zwitterionic monomer (4-vinylphenyl isothiocyanate [VPI]-1,2-dimetyl-1,4,5,6,-tetrahydropirimidine [DMTHP]) was synthesized by the reaction of VPI and a cyclic amidine DMTHP. A radical polymerization of VPI-DMTHP was carried out using 2,2′-azobis(2,4-dimethyl-4-methoxy)valeronitrile (V-70) as an initiator to give poly(VPI-DMTHP). The obtained poly(VPI-DMTHP) was not soluble in any of the investigated organic solvents, probably because it had a networked structure resulting from the ionic interactions. Copolymers of VPI-DMTHP and other vinyl monomers such as styrene, methyl methacrylate, t-butyl methacrylate, and N-vinylpyrrolidone were synthesized. The obtained copolymers were also insoluble in all of the examined common organic solvents even when the VPI-DMTHP content was low (5 mol %), indicating the existence of strong ionic interactions in the zwitterionic moieties. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2303–2309     

Synthesis and characterization of poly(4-vinylpyridine) substituted with a novel betaine salt derived from 4,5-dicyanoimidazole

A novel betaine internal salt ( 3 ) has been synthesized by the reaction of pyridine with 1-methyl-2-bromo-4,5-dicyanoimidazole ( 1 ). The reaction of pyridine with 1 serves as a model for the reaction of poly(4-vinylpyridine) with 1 . The reaction of poly(4-vinylpyridine) with 1 gives betaine salt substituted polymers which were characterized by IR, NMR, UV-visible spectroscopy, and viscometry. The substituted polymers were compared to the model compound ( 3 ) and to unsubstituted poly(4-vinylpyridine) in order to determine polymer structure and the degree of substitution. One of the substituted polymers shows polyelectrolyte behavior. Thermal characterization of the substituted polymers shows two exothermic transitions at 260 and 340°C attributed to chemical reactions of the pendant groups.     

Formation and catalytic activity of spherical composites with surfaces coated with gold nanoparticles

Micelle-supported gold composites with a polystyrene core and a poly(4-vinyl pyridine)/Au shell are synthesized using NaBH(4) to reduce a mixture of micelle and HAuCl(4) in acidic aqueous solution (pH approximately 2). The template micelle with a polystyrene core and a poly(4-vinyl pyridine) shell is formed by self-assembly of block copolymer polystyrene-block-poly(4-vinyl pyridine). The gold nanoparticles coated onto the surfaces of the composites possess an average diameter of about 15 nm. The composites are applied to catalyze the reduction of p-nitrophenol in the presence of NaBH(4), and the results indicate that the kinetic constant of the reaction increases when the composite concentration and the reaction temperature increase. In addition, research results also indicate that composites with high content of gold show higher catalytic activity and higher catalytic efficiency.     

Synthesis of pH-responsive particles with shape anisotropy

Seeded emulsion polymerization is used to produce large quantities of shape anisotropic, amphoteric particles in a size range of about 1 μm. Copolymer dicolloids (CDCs) containing pyridine groups are synthesized by swelling spherical, lightly cross-linked polystyrene seeds with a mixture of styrene and pH-responsive monomer 2-vinyl pyridine followed by secondary polymerization to contrast with their analogue homopolymer dicolloids (HDCs) where the swelling step is carried out with styrene alone. After the particles are coated with a nonionic surfactant to minimize van der Waals attractions, surface potentials and aggregation properties of dilute suspensions are studied as functions of pH and ionic strength. Compared to HDCs, which remain stable at all pH values studied (3 < pH < 9) up to an ionic strength of 5 M, the CDC particles show amphoteric behavior with strong attractions under conditions where dipolar interactions are expected to dominate.