Preparation and photoactivity of thermosensitive polymer supported metallophthalocyanine

A novel reactive metallophthalocyanine derivative,zinc tetra(2,4-dichloro-1,3,5-triazine)aminophthalo-cyanine(Zn-TDTAPc),was prepared and immobilized on poly(N-isopropylacrylamide)(PNIPAAm) by covalent bonding to obtain a thermosensitive polymer(Zn-TDTAPc-g-PNIPAAm).Compared with zinc tetraaminophthalocyanine(Zn-TAPc),Zn-TDTAPc-g-PNIPAAm exhibits excellent solubility in water and in most organic solvents.Furthermore,it has a special thermosensitive property in water and the lower critical solution temperature(LCST) is 34.1℃.It was found that both dissolved and precipitated Zn-TDTAPc-g-PNIPAAm present high photoactivity evidenced by the experiment of photocatalytic degra-dation of 1,3-diphenylisobenzofuran(DPBF) in the presence of Zn-TDTAPc-g-PNIPAAm.These proper-ties suggest that it can be used potentially in photodynamic therapy(PDT).     

Synthesis and functionalities of poly(N-vinylalkylamide). IV. Synthesis and free radical polymerization of N-vinylisobutyramide and thermosensitive properties of the polymer

Pyrolysis of (N-α-isopropoxyethyl)isobutyramide, which was obtained by the reaction of isobutyramide, 2-propanol, and acetaldehyde in the presence of conc. sulfuric acid, produced N-vinylisobutyramide (NVIBA). The free radical polymerization of NVIBA was carried out in various solvents in the presence of a radical initiator. It was found that the polymerizability of NVIBA is similar to that of N-vinylacetamide. The resulting polyNVIBA showed a lower critical solution temperature (LCST) sharply at 39°C. Thermosensitive properties of polyNVIBA were investigated in comparison with poly(N-isopropylacrylamide). © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1763–1768, 1997     

Swelling behavior of chemically crosslinked PVA gels in mixed solvents

We report the swelling behavior of chemically crosslinked polyvinyl alcohol (PVA) gels with different degrees of hydrolysis in water, several organic solvents, and their mixed solvents. The gels were dried after gelation and were put into their respective solvents. The gel volume in pure water decreased with increasing temperatures, and the total changes increased with decreasing degrees of hydrolysis. The swelling ratio depends on the solvent and its concentration. In the cases of mixed solvents of methanol–water, ethanol–water, and acetone–water, the gels shrank continuously with increasing concentrations of solvents and reached the collapsed state in the pure organic solvent. In the case of dimethyl sulfoxide (DMSO), on the other hand, the gels shrunk, swelled, and finally reached the swollen state in pure DMSO. Results of measurements using Fourier Transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD) suggested that crosslinks and microcrystallites were formed due to hydrogen bonds during the drying process after gelation. The hydrogen bonds were partly destroyed in a rich solvent, but the residual hydrogen bonds had an essential role in determining the swelling behavior in a poor solvent. The swelling behavior and the possible phase transition of the present system are discussed in terms of the solubility of polymers with different degrees of hydrolysis in given mixed solvents and in terms of the formation and destruction of physical crosslinks in the chemical PVA gels. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1978–1986, 2010     

Preparation and properties of polyvinyl acetal sponge modified by chitosan

The polyvinyl acetal sponge modified by chitosan was prepared by adding chitosan/polyvinyl alcohol (PVA) solution during the acetalation reaction of PVA and formaldehyde. The effect of vesicant and chitosan to the pore morphology, water absorption ratio, water absorption rate, expansion time and mechanical properties were studied. The polyvinyl acetal sponge modified by chitosan was used as a hemostatic packing material for the injured rabbit nasal tissue. The hemostatic effect and the healing effect of the modified sponge on the nasal mucosa after nasal surgery were studied. The results indicated that the polyvinyl acetal sponge modified by chitosan has an interconnected pore structure and the wall between large pores also has small pores. The chitosan adhered on the inner surface of the pores. The increased content of vesicant led to an increase in pore diameter, in the water absorption ratio and in expansion time. However, there was only a small change in the water absorption rate and a decrease in tensile strength and compression strength were noted. With an increase in chitosan content, the pore diameter and interconnection of the sponge was reduced. Water absorption ratio, expansion time and water absorption rate decreased, but tensile strength and compression strength improved. Observation of the rabbit nasal tissue after surgical operation suggested that polyvinyl acetal sponge modified by chitosan has an anti-inflammatory, hemostatic and anti-adherent characteristic and could promote the healing and functional recovery of rabbit nasal mucosa. __________ Translated from Journal of Jinan University (Natural Science & Medicine Edition), 2007, 28(3): 283–287 [译自: 暨南大学学报(自然科学与医学版)]     

Reversible swelling as a strategy in the development of smart membranes from electrospun polyvinyl alcohol nanofiber mats

This work presents an electrospun nanofibrous membrane for water treatment, designed to reduce its pores through polymer swelling to retain contaminants, and after that, reopening them for easy cleaning. It consists of a polyvinyl alcohol (PVA) mat crosslinked with a natural agent to avoid water solubility but allow a high swelling of its nanofibers. Then, when the membrane is brought into contact with water, a transitory state occurs during which nanofibers increase their diameter 68%, closing the pores between them. For studying the swelling reversal effect, distilled water filtering was used observing a decrease in the permeate flow over time until a steady state is reached. This phenomenon is explained by the closure of pores, and it is described with a fouling model widely used in the literature. Thanks to this decrease in the pore size, the membrane achieves a rejection rate much higher than conventional PVA electrospun membranes, being capable to retain 20 nm nanoparticles with a rejection rate up to 99%. Swelling is reversible through a simple drying process, which allows reopening the pores and cleaning the fouling easily. Both the membrane and its use strategy extend the capacity of electrospun mats in a sustainable way.     

Interpenetrating polymer networks of poly(carbonate-urethane) and polyvinyl pyridine

Simultaneous interpenetrating polymer networks (IPN's), pseudo IPN's, and liner blends of aliphatic poly(carbonate-urethane) (PCU) and polyvinyl pyridine (PVP) have been prepared and characterized by DSC, DMA, and TEM. The full IPN's of PCU and PVP had a single phase morphology only above 50 wt % PCU, as determined by both DSC and DMA and confirmed by transmission electron microscopy (TEM). However, in both pseudo IPN's of PCU and PVP and in their linear blends there exist multiple glass transitions and melting points seen by DSC and DMA indicating phase incompatibility. The full IPN's exhibited superior ultimate mechanical properties and solvent resistance as compared to the pseudo IPN's, liner blends, and the pure crosslinked PCU and PVP networks.     

Synthesis and thermal crosslinking reaction of polymers containing pendant carboxyl and epoxy groups

Polymers containing both pendant carboxyl and epoxy groups were synthesized by the radical copolymerization of p-vinylbenzyl glycidyl ether (VBGE) and itaconic acid monomethyl ester (IAME). The copolymerization proceeded smoothly under various conditions, and polymer soluble in 1,4-dioxane with no gel fraction was obtained. However, the carboxyl-epoxy addition reaction between VBGE and IAME was observed, when DMSO or DMF were used as polymerization solvents. The IR and ¹H-NMR spectrum of copolymers of VBGE and IAME showed the corresponding structure. The thermal crosslinking reaction of the resulting copolymers was examined under various conditions. Tetrabutylammonium bromide (TBAB) showed catalytic activity for the reaction. However, a 100% gel fraction of polymer was achieved after only 15 min without any catalyst, when the crosslinking reaction was performed at 150°C. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of amphiphilic diblock copolymer of polystyrene and polyvinyl alcohol using ethanolamine–benzophenone as photochemical binary initiation system

Amphiphilic diblock copolymers of polyvinyl alcohol (PVA) and polystyrene (PS), which are very difficult to prepare by common polymerization methods, have been obtained by initiation of the polymerization of styrene and vinyl acetate successively, followed by hydrolysis, using the ethanolamine–benzophenone (BP) charge-transfer complex (CTC). The effects of solvents, concentration of monomer, BP, ethanolamine, and PS prepolymer, with a reactive imino group (PS_a), on the photo-induced charge-transfer polymerization (CTP) of St and block copolymerization of VAc are discussed. The copolymer of PS-b-PVAc and the hydrolyzed product, PS-b-PVA, were characterized by FTIR, NMR, and GPC in detail. The effect of PS chain length on the crystallization of PVA was described. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 109–115, 1998     

Synthesis of nonlinear optical maleimide copolymer by polymer reaction and their electro-optic properties

Thermally stable poly(α-methyl styrene-co-maleimide) (MSMI) and poly(α-methyl styrene-co-4-carboxyphenyl maleimide) (MSCM) substrate polymers were obtained readily by free radical polymerization of comonomers. Introduction of a DR1 chromophore to the maleimide units of MSMI substrate polymer by the Mitsunobu reaction was dependent on the reaction solvent. The degree of substitution of DR1 into the MSMI polymer was bound to be 91.1 mol % and 0.4 mol % by UV spectrometers in the THF and DMF solvent, respectively. DR1 chromophore was, however, substituted in the MSCM polymer at 33.0 mol % by Mitsunobu reaction in the THF solvent. Both substrate and NLO polymer exhibited high thermal stability due to the incorporation of maleimide units in the polymer chain. The glass transition temperature (T_g) and initial decomposition temperature (T_i) of the NLO polymer were in the range of T_g = 185°C and T_i = 310–345°C. The electro-optic coefficient (r₃₃) of NLO polymer was determined with an experimental setup capable of the real-time measurement while varying both the poling field and temperature. The NLO polymer MSMI-THF had a higher r₃₃ value than MSCM-DR due to an increased degree of substitution of DR1 chromophore. MSMI-THF had a maximum r₃₃ value of 16 pm/V at 135 MV/m poling field with a 632.8 nm light source. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3715–3722, 1999     

Studies of reactions with polymers. VII. The reaction of acrylonitrile-grafted polyvinyl alcohol copolymer (PVA-g-AN) with NaOH/HCHO aqueous solution

The reaction mechanism of acrylonitrile (AN)-grafted polyvinyl alcohol (PVA) with NaOH/HCHO aqueous solution was studied. It was found that intermolecular reactions occur between the nitrile groups in PAN side chains with formaldehyde initiated by sodium hydroxide. The resultant structure proposed is based on IR analysis and elemental analysis of the composition before and after NaOH/HCHO treatment. Its thermal properties of modified membranes were also determined. © 1993 John Wiley & Sons, Inc.     

Emission characteristics of laser dyes C1 and Rh6G in cross-linked polyvinyl alcohol solutions

The lifetimes and the relative quantum yields for fluorescence of two laser dyes Coumarin 1 and Rhodamine 6G have been determined in cross-linked polyvinyl alcohol matrix. The cross-linking has been achieved using gamma radiation. The relative fluorescence quantum yields of the dyes increased with increasing cross-linking of the polymer, but the fluorescence lifetimes remained unchanged within experimental error. The results have been attributed to a reduction in the loss of the excitation energy via the internal conversion of the excited singlet state due to increase in the viscosity of the medium brought about by the increased cross-linking of the polymer.     

Relaxation behavior of methacrylic polymers with bulky hydrophilic groups in their structures

The isochrones showing the temperature dependence of the loss relaxation modulus of poly(neopentyl glycol methacrylate) present an ostensible subglass absorption called β relaxation that roughly has the same intensity as the glass–rubber relaxation, or α process. The dielectric relaxation spectrum of this polymer also exhibits a well-developed β process followed at higher temperatures by the glass–rubber, or α relaxation, which strong conductive effects only permit to be detected at high frequencies. A detailed study of the conductive contributions to the dielectric loss above T_g was carried out using a theory that assumes that the dispersion observed in tan δ in the frequency domain arises from the Maxwell–Wagner–Sillars effect combined with Nernst–Planck electrodynamic effects caused by interfacial polarizations in the interface polymer electrodes. Attempts were made to evaluate the equivalent salt concentration that would produce the conductive effects experimentally observed. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 3027–3037, 1999     

P(NIPAAm-co-Aam)共聚凝胶和PAAc/P(NIPAAm-co-Aam) IPN凝胶的溶胀与释药性能

P(NIPAAm-co-Aam)共聚凝胶和PAAc/P(NIPAAm-co-Aam) IPN凝胶的溶胀与释药性能;N-异丙基丙烯酰胺;丙烯酰胺;丙烯酸;共聚;互穿聚合物网络;水凝胶;溶胀;释药     

A novel cadmium(II) coordination polymer containing two kinds of independent one‐dimensional chain

The structure of the title compound, catena‐poly[[cadmium(II)‐di‐μ‐chlorido‐μ‐(1,4‐diazoniabicyclo[2.2.2]octane‐1‐carboxylato)] [[aquachloridocadmium(II)]‐di‐μ‐chlorido] dihydrate], {[Cd(C₈H₁₅N₂O₂)Cl₂][CdCl₃(H₂O)]·2H₂O}_n, contains two kinds of independent one‐dimensional chain, viz. {[Cd(C₈H₁₅N₂O₂)Cl₂]⁺}_n and {[CdCl₃(H₂O)]⁻}_n, and uncoordinated water molecules. Each Cd^II cation in the {[Cd(C₈H₁₅N₂O₂)Cl₂]⁺}_n chain is octahedrally coordinated by two pairs of bridging chloride ligands and two O atoms from different bridging carboxylate groups. Cd^II cations in the {[CdCl₃(H₂O)]⁻}_n chain are also octahedrally surrounded by four bridging chloride ligands, one terminal chloride ligand and one coordinated water molecule. Hydrogen bonds between solvent water molecules and these two independent chains generate a three‐dimensional framework containing two‐dimensional zigzag layers.<!?tpb=18pt>     

Mechanism of proton conductivity in polyvinyl alcohol-phenolsulfonic acid membranes from <Superscript>1</Superscript>H and <Superscript>13</Superscript>C NMR data

With line narrowing during magic angle spinning in solid-state NMR, molecular mobility and hydration in composite membranes based on polyvinyl alcohol (PVA) and phenol-2,4-disulfonic acid (PSA) were studied as functions of the ratio of the acidic and polymeric components, the degree of cross-linking in the polymeric matrix, and the moisture content. It is shown that at high relative humidity proton transport takes place by means of the network of hydrogen bonds, which are formed by the H⁺ counterions, sulfonate groups, and water molecules. At low moisture content, the hydroxyl groups in PVA play an active role in proton transport.     

几种烟煤及其热处理后的溶胀性能研究

研究了四种不同变质程度烟煤及其二硫化碳/N-甲基-2-吡咯烷酮（CS2/NMP）混合溶剂(1∶1,vol)的抽提物在不同溶剂中的溶胀性能,同时考察了四种煤样不同温度热处理后其溶胀性能的变化。结果表明,煤的溶胀率随煤化度增加而有所降低;变质程度较低的烟煤在极性溶剂中的溶胀率大于非极性溶剂,随着煤化度的增加,两者溶胀度差距减小;四种烟煤经混合溶剂抽提后,其抽余煤的交联密度降低,溶胀率增加。四种煤样150℃热处理后在CS2中的溶胀率均有所增加,表明热处理可以降低煤的交联密度。随着热处理温度提高至240℃,除气煤外,其余三种煤样在NMP和CS2中溶胀率均进一步增大,说明其交联密度进一步降低。这一结果与热处理煤样在混合溶剂中抽提率的变化趋势一致,如240℃热处理后瘦煤的抽提率由原煤的6.9%提高到17.3%。红外光谱研究表明,经过适当温度的热处理,可以脱除煤分子中的羰基和羟基等含氧官能团,破坏煤结构中的氢键,从而降低煤的交联密度,提高煤的溶胀率及其在混合溶剂中的抽提率。     

Interpolymer complex between hydroxypropyl cellulose and maleic acid-styrene copolymer: phase behavior of semi-dilute solutions

The phase behavior of a water/hydroxypropyl cellulose/maleic acid-styrene copolymer (H2O/HPC/MAc-S) system was investigated in the semi-dilute range by turbidimetry, rheology, and optical microscopy. The two polymers under investigation form interpolymer complexes via hydrogen bonding. In the case of a total polymer concentration of cpol = 5 mg . mL(-1) a second phase segregates upon heating the homogeneous ternary system. By applying a constant shear rate (gamma = 50 s(-1)) the phase separation temperature of the system is 10-15 degrees C lower than for an unsheared one. For cpol = 10 mg . mL(-1) phase separation has already occurred at room temperature when the two binary polymer solutions are mixed. The distribution of the partners among the coexisting phases was examined by FT-IR spectroscopy. The stoichiometry of the interpolymeric complex (IPC) was estimated to be HPC/MAc-S = 40:60 (w/w) independent of cpol.     

Dynamic and equilibrium swelling of a sulfonic acid superabsorbent copolymer in salt solutions

Superabsorbent copolymers were synthesized by free radical reverse emulsion from the monomers acrylamide and 2‐acrylamido‐2‐methyl‐propanosulfonic acid with a divinyl crosslinker (methylene‐bisacrylamide). The copolymer synthesized was then identified by Fourier transform infrared spectroscopy, its porosity was examined by electronic microscopy, and its specific gravity was determined by the conventional procedure. The dynamic and equilibrium swelling behavior of the copolymer was studied, in water and in salt solutions, at 25 °C (chlorides and sulfates of sodium and magnesium). As to the equilibrium swelling, the influence of the pH as well as of the salt type and its concentration was observed. As to the dynamic swelling, it was interpreted in terms of both a simple power of time equation, and a more detailed model based on a coupled diffusion‐relaxation mechanism. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 505–514, 2004     

Synthesis,characterization and properties of polycarbonate containing carboxyl side groups

Diphenolic Acid, DPA [bis(4-hydroxyphenyl)pentanoic acid] can be made from cellulose-rich waste. The t-butyl ester was converted to homo- and copolycar- bonates (with bis-phenol-A, BPA). Deblocking the ester yielded polycarbonates with pendent carboxyl groups that exhibit all the properties of polyelectrolytes and retain solubility in aqueous base without degradation for long periods.