Supramolecular Complex of Poly(styrene)-b-Poly(4-vinylpyridine) and 1-Pyrenebutyric Acid in Thin Film

Summary: Here, we have described a novel supramolecular complex (SMC) between poly(styrene)-b-poly(4-vinylpyridine) (PS-b-P4VP) and 1-pyrenebutyric acid (PBA) and studied of its self assembly in thin film. PBA will make supramolecular complex with the P4VP block due to strong hydrogen bonding between the carboxylic group of 1-pyrenebutyric acid and pyridine ring of P4VP. The formation of supramolecular complex between PS-P4VP and PBA through hydrogen bonding is investigated through FTIR study. The supramolecular complex of PS-b-P4VP and 1-pyrenebutyric acid changed the block copolymer morphology from cylindrical to lamella in thin film due to the increase of the volume fraction of P4VP (PBA). In both cases (parent block copolymer and SMC), the microdomains are oriented normal to the substrate after annealing in a selective solvent. Pure block copolymer shows cylindrical morphology with a periodicity of ∼26 nm, whereas the SMC shows lamellar morphology with a periodicity of ∼ 29 nm. After fabricating the thin film from SMC, 1-pyrenebutyric acid can be easily removed by dissolving the thin film in ethanol to transform the block copolymer thin film into nanotemplate or membrane.     

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.     

Fabrication of metallized nanoporous films from the self-assembly of a block copolymer and homopolymer mixture

Inorganic compound HAuCl4, which can form a complex with pyridine, is introduced into a poly(styrene-block-2-vinylpyridine) (PS-b-P2VP) block copolymer/poly(methyl methacrylate) (PMMA) homopolymer mixture. The orientation of the cylindrical microdomains formed by the P2VP block, PMMA, and HAuCl4 normal to the substrate surface can be generated via cooperative self-assembly of the mixture. Selective removal of the homopolymer can lead to porous nanostructures containing metal components in P2VP domains, which have a novel photoluminescence property.     

Adsorption of poly(N-isopropylacrylamide-co-4-vinylpyridine) onto core-shell poly(styrene-co-methylacrylic acid) microspheres

Adsorption of the thermoresponsive copolymer of poly(N-isopropylacrylamide-co-4-vinylpyridine) (PNIPAM-co-P4VP) onto the core-shell microspheres of poly(styrene-co-methylacrylic acid) (PS-co-PMAA) is studied. The core-shell PS-co-PMAA microspheres are synthesized by one-stage soap-free polymerization in water. The copolymer of PNIPAM-co-P4VP is synthesized by free radical polymerization of N-isopropylacrylamide and 4-vinylpyridine in the mixture of DMF and water using K₂S₂O₈ as initiator. Adsorption of PNIPAM-co-P4VP onto the core-shell PS-co-PMAA microspheres results in formation of the composite microspheres of PS/PMAA-P4VP/PNIPAM. The driven force to adsorb the copolymer of P4VP-co-PNIPAM onto the core-shell PS-co-PMAA microspheres is ascribed to hydrogen-bonding and electrostatic affinity between the P4VP and PMAA segments. The resultant composite microspheres of PS/PMAA-P4VP/PNIPAM with surface chains of PNIPAM are thermoresponsive in water and show a cloud-point temperature at about 33 °C.     

Novel comb-type hydrogels of net-[PP-g-AAc]-g-4VP synthesized by gamma radiation,with possible application on Cu2+ immobilization

A novel comb-type grafted hydrogel system of net-[PP-g-AAc]-g-4VP was synthesized by gamma radiation in three steps. In the first step a pH sensitive graft copolymer of AAc onto PP film was obtained by radiation grafting of acrylic acid (AAc) onto polypropylene (PP) films in aqueous solution at radiation doses of 10 kGy with a ⁶⁰Co source. The grafted side chains of poly (acrylic acid) (PAAc) were then cross-linked with gamma radiation at different radiation doses to give net-[PP-g-AAc]. Finally, 4-vinylpyridine (4VP) was grafted into the net-[PP-g-AAc]. The comb-type grafted hydrogel obtained, net-[PP-g-AAc]-g-4VP, has been studied through determination of graft yield and swelling behavior at room temperature. Two critical pH values were found for net-[PP-g-AAc]-g-4VP at 4.5 and 7.2. Initial studies on the immobilization of Cu²⁺ ions from solution into net-[PP-g-AAc]-g-4VP films were performed.The comb-type grafted hydrogel, grafted onto PP was also characterized by differential scanning calorimetry (DSC), scanning electronic microscopy (SEM) and FTIR-ATR.     

Meeting announcement

Diffusion and solution behavior of methanol vapor in two diblock copolymers, poly(2-vinylpyridine)—block—polyisoprene [P(2VPbI)] and poly(2-vinylpyridine)—block—polystyrene [P(2VPbS)], was studied by the weighing method at 25°C. The domain structure of films of both copolymers showed an alternating lamellar arrangement. Methanol is a good solvent for P2VP, but a nonsolvent for PI and PS. Methanol dissolved exclusively in the P2VP phase of the copolymers. For both copolymer systems, absorption and desorption processes of non-Fickian type were observed as characterized by a thickness anomaly. However, the magnitude of the deviations from purely Fickian behavior was small, and the integral diffusion coefficient, D?, was obtainable with reasonable accuracy. At low and medium concentrations, D? for P(2VPbI) was greater, by about one order of magnitude, than that for P2VP, while D? for P(2VPbS) was lower than that for P2VP. A similar trend was observed in plots of the permeability coefficient against the vapor pressure of methanol. The results indicate that the rubbery PI phase may facilitate the transport of penetrant molecules in the P(2VPbI) film. On the other hand, the glassy PS phase in the P(2VPbS) film merely interferes with the transport of methanol molecules.     

Microphase separation in thin films of supramolecular assemblies composed of a triblock copolymer and low-molecular-weight additive

The phase behavior of supramolecular assemblies (SMAs) formed by poly(4-vinylpyridine)-block-polystyrene-block-poly(4-vinylpyridine) (P4VP-b-PS-b-P4VP) triblock copolymer with 2-(4′-hydroxybenzeneazo)benzoic acid (HABA) was investigated with respect to the molar ratio (X) between HABA and 4VP monomer unit in bulk as well as in thin films. The results were compared with SMAs formed by a PS-b-P4VP diblock copolymer of similar composition as the triblock but half the molecular weight to ascertain the effect of molecular architecture on microphase separation. In bulk, both the di- and triblock SMAs showed composition-dependent morphological transitions, which could be tuned by HABA/4VP molar ratio. The domain spacing of the SMA was not significantly affected by the molecular architecture of the constituting block copolymers. In thin films also, both the di- and triblock SMAs showed more or less similar morphological transitions depending on X. Interestingly, the domain orientation of the cylindrical or lamellar microdomains in the SMAs was influenced by the molecular architecture of the block copolymer. After chloroform annealing, although the diblock SMAs showed in-plane orientation of the domains, triblock SMAs showed perpendicular domain orientation. The perpendicular orientation of the microdomains in triblock was favored because it allowed the mid-PS blocks to acquire normal distribution of loop and bridged conformations. Furthermore, the orientation of the lamellar and cylindrical microdomains of the diblock SMAs was found to switch to perpendicular orientation after annealing in 1,4-dioxane vapors. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1594–1605, 2010     

Kinetics of the addition of electrophilic vinyl reagents on protonated tertiary amines supported by a polymeric chain

Starting from the mechanism of the addition of vinyl methyl ketone to protonated tertiary polyamine, we examined the kinetics of addition of acrylic acid, acrylamide and methyl acrylate to P4VP in the presence of HBr. The reactivities depend on the electrophilic character of the double bond; the kinetics of addition of vinyl methyl ketone to poly(2-methyl-5-vinylpyridine), poly(2-vinylpyridine), poly(2-vinylquinoline) and poly(dimethylaminostyrene) in the presence of HBr depend essentially on the steric hindrance of the tertiary amine.     

Charge mosaic membrane with a microstructure of poly(styrene-b-4-vinylpyridine)

Well defined AB and BAB type poly[styrene(ST)-b-4-vinylpyridine(4VP)]s were prepared by anionic living polymerization in tetrahydrofuran (THF) at ?78°C. Casting AB and BAB type poly(ST-b-4VP)s with a composition of about 50 mol% PST from 1,1,2-trichloroethane (TCE) produced specimens with lamellar microdomain structures. Quaternization of P4VP and sulfonation of PST domains (lamellar and spherical structures), accompanied by each domain fixing, were carried out under various reaction conditions. The piezodialysis of the prepared charge mosaic membrane with its lamellar microdomain structure was measured from a sodium chloride (NaCl) aqueous solution. The results are discussed in some detail.     

An in situ GISAXS study of selective solvent vapor annealing in thin block copolymer films: Symmetry breaking of in-plane sphere order upon deswelling

Thin films of asymmetric poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) block copolymers are studied by means of in situ grazing-incidence small-angle X-ray scattering (GISAXS) during solvent vapor annealing in tetrahydrofuran, a solvent selective for the PS majority block of the copolymer. Upon swelling, PS-b-P4VP block copolymers form hexagonal arrays of spherical P4VP microdomains in a PS matrix in films 7–9 layers thick. Deswelling the films induces a transition from hexagonal to face-centered orthorhombic (fco) symmetry, which is stable only at ∼7 layers of spherical microdomains. Dry films show co-existing hexagonal and orthorhombic symmetries when the solvent is removed slowly, whereas instantaneous solvent removal suppresses the fco structure, resulting in films with only hexagonal structure. The in-plane order of microdomains is significantly deteriorated in dry films independent of the solvent removal rate.Spherical block copolymer microdomains are known to undergo a transition from hexagonal to orthorhombic packing in isothermally annealed thin films when the number of sphere layers is increased from 4 to 5. In this paper, in situ GISAXS experiments reveal that a similar transition occurs during solvent vapor annealing in a selective solvent. Interestingly, the transition from hexagonal to orthorhombic packing of spheres occurs as solvent is removed from a thin block copolymer film. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 331–338     

Synthesis of poly(4-vinylpyridine) and block copoly (4-vinylpyridine-b-styrene) by atom transfer radical polymerization using 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazamacrocyclotetradecane as ligand

Poly(4-vinylpyridine) (P4VP) and block copolymer, poly(4-vinylpyridine-b-styrene) (P4VP-b-PSt) were prepared by atom transfer radical polymerization (ATRP) using 1-phenylethyl chloride as initiator, CuCl and 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazamacrocyclotetradecane (Me₆[14]aneN₄) as catalyst and ligand. The polymerization of 4VP was carried out in 2-propanol at 40 °C. GPC and NMR studies show that the plot of ln([4VP]₀/[4VP]) against the reaction time is linear, and the molecular weight of the resulting P4VP increased linearly with the conversion. Within 3 h, the conversion can reach almost 90%. P4VP-b-PSt amphiphilic block copolymer with low polydispersity index (M_w/M_n ≈ 1.2) is also obtained by ATRP of St in DMF at 110 °C using P4VP-Cl as macroinitiator, CuCl/ Me₆[14]aneN₄ as catalyst.     

Thermal degradation of poly(vinylpyridine)s

The thermal stability and the temperature at which maximum degradation yields are detected were quite similar for both poly(2-vinylpyridine) (P2VP) and poly(4-vinylpyridine) (P4VP). However, considerable differences among the thermal degradation products of both polymers were detected indicating a correlation between the polymer structure and the degradation mechanism. Direct pyrolysis mass spectrometry analyses revealed that P2VP degrades via a complex degradation mechanism, yielding mainly pyridine, monomer, and protonated oligomers, whereas depolymerization of P4VP takes place in accordance with the general thermal behaviour of vinyl polymers. The complex thermal degradation behaviour for P2VP is associated with the position of the nitrogen atom in the pyridine ring, with σ-effect.     

聚(丙烯酸钠-4-乙烯基吡啶)的生物降解性和功能性研究

用自由基共聚法制备了一系列可生物降解的功能聚合物聚(丙烯酸钠-4-乙烯基吡啶)[P(SA-co-4VP)],研究了其组成和分子量与生物降解性、资合性及分散性间的关系.结果表明:聚合物中小乙烯基吡啶含量越大,P(SA-co-4VP)的生物降解越显著.分子是一定时,少量的个乙烯基吡啶引入聚丙烯酸钠主链是增强聚合物生物降解性和保持原有功能特性的有效途径.     

Self‐assembled complexes of poly(acrylic acid) and poly(styrene)‐block‐poly(4‐vinyl pyridine)

Polymer complexes were prepared from high molecular weight poly(acrylic acid) (PAA) and poly(styrene)‐block‐poly(4‐vinyl pyridine) (PS‐b‐P4VP) in dimethyl formamide (DMF). The hydrogen bonding interactions, phase behavior, and morphology of the complexes were investigated using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), dynamic light scattering (DLS), atomic force microscopy (AFM), and transmission electron microscopy (TEM). In this A‐b‐B/C type block copolymer/homopolymer system, P4VP block of the block copolymer has strong intermolecular interaction with PAA which led to the formation of nanostructured micelles at various PAA concentrations. The pure PS‐b‐P4VP block copolymer showed a cylindrical rodlike morphology. Spherical micelles were observed in the complexes and the size of the micelles increased with increasing PAA concentration. The micelles are composed of hydrogen‐bonded PAA/P4VP core and non‐bonded PS corona. Finally, a model was proposed to explain the microphase morphology of complex based on the experimental results obtained. The selective swelling of the PS‐b‐P4VP block copolymer by PAA resulted in the formation of different micelles. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1192–1202, 2009     

Synthesis of poly(styrene-tetrahydrofuran-2-methyl-2-oxazoline) triblock and graft copolymers

Poly[styrene (ST)-tetrahydrofuran (THF)-2-methyl-2-oxazoline(MeOz)] triblock and graft copolymers were prepared by ionic polymerizations. Poly(ST-THF) graft copolymers were synthesized by coupling of ST-4-vinylpyridine (4VP) copolymer with a large excess of PTHF dication. The ion coupling of PST dianion with PTHF dication was accompanied by the side reaction (abstraction of α proton of oxonium ion). After tosylation of terminal hydroxyl groups of PTHF blocks, cationic copolymerizations of MeOz with poly(ST-THF) block and graft copolymers were carried out, and characteristics of produced copolymers were investigated in some detail.     

Synthesis,Characterization and Application of Amphiphilic Copolymer Poly(vinyl alcohol)-g-Poly(butyl acrylate)

An amphiphilic graft copolymer poly(vinyl alcohol)-g-poly(butyl acrylate) (PVA-g-PBA) was synthesized by grafting butyl acrylate (BA) onto poly(vinyl alcohol) (PVA) with potassium persulfate (KPS) as free radical initiator in N₂ atmosphere and aqueous medium. The formation of graft copolymer was confirmed by means of infrared spectroscopy (IR). The influences of initiator, monomer concentration and reaction time on the percentage of monomer conversion(C _M), graft degree(Gd) and graft efficiency(Ge) have been discussed in detail. PVA-g-PBA was used as compatibilizer in blends of chlorinated polyethylene (CPE)/ poly(acrylic acid-co-acrylamide)[P(AA-AM)], and the compatibility between CPE and P(AA-AM) was also investigated.     

Hydrogen bonded layer-by-layer assembly of poly(2-vinylpyridine) and poly(acrylic acid): Influence of molecular weight on the formation of microporous film by post-base treatment

This article describes the buildup of hydrogen bonded multilayer film of poly(2-vinylpyridine) (P2VP) and poly(acrylic acid) (PAA), and the influence of polymer molecular weight on the formation of microporous film by post-base treatment. The formation of a microporous film involved a two-step mechanism: the release of PAA from P2VP/PAA multilayer, and the reorganization of the remaining P2VP on the substrate. Fourier transform infrared spectroscopy (FT-IR) indicated that the release of PAA from hydrogen bonded multilayer was a rapid process, which was almost independent of the molecular weight of PAA. Furthermore, the molecular weight of P2VP had a great effect on micropore formation by immersing the P2VP/PAA multilayer in basic solution. The rate of micropore formation increased with increasing molecular weight. We anticipate that a comparative study on P2VP/PAA films containing high or low molecular weight polymer provides a way to control the surface morphology, and will be helpful and constructive for the forthcoming discussion about the formation of the microporous film.     

Copolymer of poly(4-vinylpyridine)-g-poly(ethylene oxide) respond sharply to temperature, pH and ionic strength

The stimuli-responsive copolymers with poly(ethylene oxide) (PEO) as side chain were prepared by free-radical copolymerization of methacrylamide end-capped PEO macromonomer and 4-vinylpyridine (4VP). Phase transition behavior of these copolymers of poly(4-vinylpyridine)-g-poly(ethylene oxide) (P4VP-g-PEO) was investigated as a function of polymer concentration, temperature, pH and ionic strength by monitoring the turbidity of the polymer solutions. The copolymers displayed sharp response to temperature and pH. The LCST of P4VP-g-PEO copolymer increased with the increase of PEO content and decreased with increasing pH due to the deprotonation of the pyridine ring, indicating well-tunable LCST. In addition, the LCST of P4VP-g-PEO9 presented a unique phase transition behavior with varying salt concentration, showing a minimum with 1 M NaCl solution at pH 6.0.     

Self-assembly behavior of A-B diblock and C-D random copolymer mixtures in the solution state through mediated hydrogen bonding

We have synthesized poly(methyl methacrylate- b-4-vinylpyridine) (PMMA- b-P4VP) and poly(styrene- r-vinylphenol) (PS- r-PVPh) copolymers by using anionic and free radical polymerizations, respectively. Well-defined micelles through hydrogen bonding have been prepared by mixing PMMA- b-P4VP diblock copolymer and PS- r-PVPh random copolymer in a single solvent. Block copolymers were mixed with random copolymers, with various [N]/[OH] ratios (4/1, 2/1, 1/1, and 1/4) in which "[N]/[OH]" represents the molar ratio of pyridine groups on P4VP to hydroxyl groups on PVPh. The presence distribution of PVPh/P4VP and PVPh/PMMA hydrogen bonding depends on the feeding ratio of PVPh to P4VP. When the PVPh content is lower than that of P4VP, hydrogen bonding occurs only between PVPh and P4VP; with excess PVPh, additional hydrogen bonding between PVPh and PMMA would occur. Furthermore, the effect of the solvent quality on the self-assembly behavior of PMMA- b-P4VP/PS- r-PVPh blends is investigated by considering tetrahydrofuran (THF) and dimethylformamide (DMF) as common solvents. We can mediate the strength of hydrogen bonding in blend systems by adopting different solvents and inducing different morphology transitions.     

Charge mosaic membranes: Microdomain fixing of (polystyrene–poly-4-vinylpyridine) sequential copolymers prepared by macromonomer methods

Polystyrene (PST) macromonomers having several allyl groups at the ends were synthesized by the mechanical scission reaction of the main chain in the presence of diallylmalonic acid diethyl ester (DAME). Photosensitive benzophenone groups were introduced on a PST macromonomer molecule by the reaction of these PST macromonomers with benzoyl chloride. The palm-treelike (PST–poly-4-vinylpyridine (P4VP)) sequential copolymers with different compositions were prepared by the radical copolymerization of PST macromonomer with 4VP. The morphological observation of these sequential copolymers was carried out by the transmission electron microscopy. The PST block microdomains were fixed by photocrosslinks (UV irradiation) in the presence of mono- and bifunctional unsaturated compounds in the state of mesomorphic structures. The microdomain fixing of P4VP blocks was carried out by using the vapor of 1, 4-dibromobutane (DBB). After subsequent chemical modifications (quaternization of residual P4VP blocks and sulfonation of PST blocks), the effect of microdomain fixings was elucidated from the moisture content of positive and negative regions. These results are discussed in some detail.