辣根过氧化物酶酶促体系引发丙烯酰胺聚合的研究

对辣根过氧化物酶(HRP)、H2O2和乙酰丙酮(ACAC)组成的三元醇促体系引发的丙烯酰胺(AAM)聚合进行了研究。在膨胀计中考察了反应温度和HRP、ACAC、H2O2及AAM初始浓度对酶促体系引发AAM聚合动力学行为的影响,确定了适宜的反应条件。用FTIR和GPC对聚合产物进行表征,得到的聚丙烯酰胺的数均分子量为10^5-10^6,分子量分布指教DI为2-3。     

Polymeric Forms of Plant Flavonoids Obtained by Enzymatic Reactions

Naringenin is one of the flavonoids originating from citrus fruit. This polyphenol is mainly found in grapefruit, orange and lemon. The antioxidant and antimicrobial properties of flavonoids depend on their structure, including the polymeric form. The aim of this research was to achieve enzymatic polymerization of naringenin and to study the properties of poly(naringenin). The polymerization was performed by methods using two different enzymes, i.e., laccase and horseradish peroxidase (HRP). According to the literature data, naringenin had not been polymerized previously using the enzymatic polymerization method. Therefore, obtaining polymeric naringenin by reaction with enzymes is a scientific novelty. The research methodology included analysis of the structure of poly(naringenin) by NMR, GPC, FTIR and UV-Vis and its morphology by SEM, as well as analysis of its properties, i.e., thermal stability (DSC and TGA), antioxidant activity (ABTS, DPPH, FRAP and CUPRAC) and antimicrobial properties. Naringenin oligomers were obtained as a result of polymerization with two types of enzymes. The polymeric forms of naringenin were more resistant to thermo-oxidation; the final oxidation temperature T_o of naringenin catalyzed by laccase (poly(naringenin)-laccase) was 28.2 °C higher, and poly(naringenin)-HRP 23.6 °C higher than that of the basic flavonoid. Additionally, due to the higher molar mass and associated increase in OH groups in the structure, naringenin catalyzed by laccase (poly(naringenin)-laccase) showed better activity for scavenging ABTS^+• radicals than naringenin catalyzed by HRP (poly(naringenin)-HRP) and naringenin. In addition, poly(naringenin)-laccase at a concentration of 5 mg/mL exhibited better microbial activity against E. coli than monomeric naringenin.     

胶囊固定化辣根过氧化物酶酶促体系引发丙烯酰胺聚合研究

研究了以海藻酸钠／壳聚糖／海藻酸钠为囊壁材料的胶囊固定化辣根过氧化物酶的制备及其影响因素,并将肢囊固定化辣根过氧化物酶／乙酰丙酮／H2O2酶促体系用于引发丙稀酰胺的聚合。结果表明,作为囊壁材料之一的壳聚糖的平均分子量以1万左右为宜,以柠檬三酸钠溶液为溶芯荆的溶芯时间控制在2～4min时,固定化率可达60％,相对于游离酶,其相对活力约为60％。胶囊固定化辣根过氧化物酶／乙酰丙酮／H2O2酶促体系可引发丙稀酰胺的聚合。     

Water‐soluble,biocompatible polyphosphazenes with controllable and pH‐promoted degradation behavior

The synthesis of a series of novel, water‐soluble poly(organophosphazenes) prepared via living cationic polymerization is presented. The degradation profiles of the polyphosphazenes prepared are analyzed by GPC, ³¹P NMR spectroscopy, and UV–Vis spectroscopy in aqueous media and show tunable degradation rates ranging from days to months, adjusted by subtle changes to the chemical structure of the polyphosphazene. Furthermore, it is observed that these polymers demonstrate a pH‐promoted hydrolytic degradation behavior, with a remarkably faster rate of degradation at lower pH values. These degradable, water soluble polymers with controlled molecular weights and structures could be of significant interest for use in aqueous biomedical applications, such as polymer therapeutics, in which biological clearance is a requirement and in this context cell viability tests are described which show the non‐toxic nature of the polymers as well as their degradation intermediates and products. © 2013 The Authors Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 287–294     

Living Carbocationic Polymerization. V. Linear Telechelic Polyisobutylenes by Bifunctional Initiators

The synthesis of α,ω-di-t-chloropolyisobutylene has been accomplished by living polymerization using aliphatic and aromatic tert-diacetate initiators in conjunction with BCl₃ coinitiator in various solvents in the ?20 to ?70°C range. The living nature of the polymerizations was demonstrated with the instantaneous initiators 2,4,4,6-tetramethyl-heptane-2,6-diacetate and 1,4-di(2-propyl-2-acetate)benzene by linear [Mbar]_n versus amount of PIB formed (W _PIB) plots starting at the origin. The formation of undesirable indanyl structures that arise with the aromatic initiator can be suppressed by decreasing the temperature and the polarity of the polymerization medium (i.e., by using CH₃Cl/n-C₆H₁₄ mixtures). Living polymerization of isobutylene can also be obtained with noninstantaneous initiators, e.g., 2,5-dimethylhexane-2,5-diacetate, 2,5-dimethylhexyne-2,5-diacetate. However, with these systems the initiator efficiency is less than 100%.     

A Water‐Soluble Polycarbonate With Dimethylamino Pendant Groups Prepared by Enzyme‐Catalyzed Ring‐Opening Polymerization

A water‐soluble polycarbonate with dimethylamino pendant groups, poly(2‐dimethylaminotrimethylene carbonate) (PDMATC), is synthesized and characterized. First, the six‐membered carbonate monomer, 2‐dimethylaminotrimethylene carbonate (DMATC), is prepared via the cyclization reaction of 2‐(dimethylamino)propane‐1,3‐diol with triphosgene in the presence of triethylamine. Although the attempted ring‐opening polymerization (ROP) of DMATC with Sn(Oct)₂ as a catalyst fails, the ROP of DMATC is successfully carried out with Novozym‐435 as a catalyst to give water‐soluble aliphatic polycarbonate PDMATC with low cytotoxicity and good degradability.     

Self‐Assembly in Water of Poly(acrylic acid)‐Based Diblock Copolymers Synthesized by Nitroxide‐Mediated Polymerization

Summary: Amphiphilic diblock copolymers consisting of a hydrophilic block, poly(acrylic acid), and a hydrophobic block, polystyrene, were synthesized by direct nitroxide‐mediated polymerization using the PS block as a macro‐initiator for the first time. Several techniques were used to characterize the amphiphilic block copolymers (size exclusion chromatography, NMR spectroscopy). The proposed method can lead to samples with a broad range of composition and molar mass. Preliminary studies of their self‐assembly in aqueous medium using fluorescence spectroscopy and small‐angle neutron scattering are presented.

Schematic of the formation of the PS‐b‐PAA block copolymers and their micellization in aqueous media.     

Non‐Ideal Polymerization Kinetics of a Cationic Double Charged Acryl Monomer and Solution Behavior of the Resulting Polyelectrolytes

The radical polymerization of bis‐1,3(N,N,N‐trimethylammonium)‐2‐propylmethacrylate dichloride revealed non‐ideality with 0.59 and 4.4 for the reaction orders of the initiator and monomer concentration, respectively. Further, autoacceleration was observed from less than 10% conversion onwards. Degradative chain transfer to the monomer was concluded to explain the initiator exponent. Monomer association and electrostatic effects are hypothesized to govern the monomer exponent and autoacceleration. The exponential concentration dependent increase of the viscosity of the monomer solution and the relatively low overall activation energy E_a = 31.5 kJ · mol⁻¹ support the hypothesis. Counterion activity measurements confirmed strong counterion condensation as expected for a charge distance of 0.12 nm.

     

Hyperbranch‐polyethyleniminated functional polymers. I. Synthesis,characterization of novel ABA type of dumbbell‐like polyethyleniminated polyoxypropylenediamines,and their complexing properties with copper(II) ions in aqueous solution

Novel ABA‐type dumbbell‐like water‐soluble copolymers [D230(EI)₄, D400(EI)₄, and D400(EI)₈] were synthesized by introducing ethylenimine (EI) groups into both sides of polyoxypropylenediamines via a simple in situ ethylamination of polyoxypropylenediamine with 2‐chloroethylamine hydrochloride. The structures of the resultant polymers were identified by Fourier transform infrared spectroscopy and ¹H NMR. The percentages of primary, secondary, and tertiary amine present were determined by the potentiometric titration method after treatments with the appropriate chemicals of salicylaldehyde and acetic anhydride. The surface tension and solubilizing behavior of pyrene in the presence of these polymers in aqueous medium were also investigated, and the efficiency to reduce the surface tension and solubilizing behavior of pyrene depends on the attachments of EI to polymer backbone. The chelating properties of these polymers were examined quantitatively by ultraviolet–visible (UV–vis) spectroscopy in the presence of Cu²⁺ ions in aqueous solution, and continuous variation analysis revealed that the most stable complex is formed at the normality ratio of [N]/[Cu²⁺] = 3.0. UV–vis spectroscopy and transmission electron microscopy were used to evaluate the dumbbell‐like water‐soluble copolymer, D400(EI)₈, as a stabilizer for preparing colloidal noble metal nanoparticles (Au and Pt) in aqueous solution. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1360–1370, 2003     

Synthesis of Functional Polymers by Post‐Polymerization Modification

Post‐polymerization modification is based on the direct polymerization or copolymerization of monomers bearing chemoselective handles that are inert towards the polymerization conditions but can be quantitatively converted in a subsequent step into a broad range of other functional groups. The success of this method is based on the excellent conversions achievable under mild conditions, the excellent functional‐group tolerance, and the orthogonality of the post‐polymerization modification reactions. This Review surveys different classes of reactive polymer precursors bearing chemoselective handles and discusses issues related to the preparation of these reactive polymers by direct polymerization of appropriately functionalized monomers as well as the post‐polymerization modification of these precursors into functional polymers.     

Polymerization of substituted phenylacetylenes with a novel,water‐soluble Rh–vinyl complex in water

A novel, water‐soluble Rh complex, (nbd)Rh[PPh₂(m‐NaOSO₂C₆H₄)] [C(Ph)?CPh₂] ( 1 ) was synthesized by the reaction of [(nbd)RhCl]₂, Ph₂P(m‐NaOSO₂C₆H₄) and Ph₂C?C(Ph)Li, whose structure was determined by NMR and IR spectroscopies. The Rh catalyst 1 induced the polymerization of phenylacetylene (PA) in water to give two kinds of polymers; one was soluble in organic solvents such as tetrahydrofuran (THF) and CHCl₃, and the other was insoluble in common organic solvents. The polymerization of sodium p‐ethynylbenzoate (p‐NaOCO‐PA) homogeneously proceeded with 1 in water at 60 °C to give the polymer in high yield. Poly(p‐NaOCO‐PA) was treated with 1 N HCl and then reacted with (CH₃)₃SiCHN₂ to obtain poly(p‐MeOCO‐PA). The methyl‐esterified polymer was insoluble in THF and CHCl₃, which suggests that the formed poly(p‐MeOCO‐PA) has cis–cisoidal structure. The polymer obtained from the polymerization of [p‐CH₃(OCH₂CH₂)₂O₂CC₆H₄]C?CH with 1 in water was soluble in methanol, ethanol, and THF, and partly soluble in water. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2100–2105, 2004     

Selective Enzymatic Grafting by Steric Control

Enzymatic grafting of caprolactone was carried out from poly[styrene‐co‐(4‐vinylbenzyl alcohol)] containing 10% hydroxyl functional monomer and compared with the grafting of vinyl acetate. A molecular weight increase due to the grafting of polycaprolactone was observed by size exclusion chromatography. Closer investigation of the grafting density by ¹H NMR revealed an upper limit to the amount of grafting of about 50–60% of the pendant hydroxyl groups leaving unreacted hydroxyl groups on the polymer backbone available for subsequent reactions. The higher grafting density (95%) obtained with vinyl acetate suggests that this is not due to limited accessibility of the backbone but sterical constrains. Moreover, the grafting action of polycaprolactone seems to be a combination of grafting from by monomer initiation and grafting onto by transesterification of polycaprolactone.

     

Water‐soluble conjugated polymers: Synthesis and optical properties

Two sets of water‐soluble poly(phenylene vinylene)s were synthesized and their optical properties were studied. The aqueous solubility of all these polymers is rendered by pendant sulfonate groups. One set of polymers (polymer I series) contains, in addition to the sulfonate pendants, dimethoxy substituents, while the other (polymer II series) contains oligo(ethylene oxide) side chains. Within each set, polymers containing lithium (Ia and IIa), sodium (Ib and IIb), and potassium (Ic and IIc) counter ions were prepared. The two sets of polymers showed different properties from physical appearance (fiber vs film) to thermal properties and to optical properties. It was found that set I polymers, with shorter side chains, exhibit stronger aggregation in aqueous solutions than set II polymers, which led to their lower fluorescence quantum yields and lower polymer‐to‐MV²⁺ quenching efficiencies. Within each set, the effect of counter ions on optical properties was noted. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5123–5135, 2007     

A review of: “The Effects of Hostile Environments on Coattings and Plastics,Acs. D. P. Garner and G. A. Stahl (Editors): Symposium Series 229, American Chemical Society,Washington, D.C., 1983, 339 pp., U.S. and Canada $47.95, export $57.95.”

Rh‐catalyzed polymerization of a new N‐propargylamide monomer having a galactose residue was investigated. The polymerization proceeded in a mixed solvent of THF and water to produce the galactose‐carrying poly(N‐propargylamide) consisting of cis‐isomer. The copolymerization of the monomer with the N‐propargylamide having the alkyl chain was also carried out.     

Green Polymer Chemistry VIII: Synthesis of Halo‐ester‐Functionalized Poly(ethylene glycol)s via Enzymatic Catalysis

Halo‐ester‐functionalized poly(ethylene glycol)s (PEGs) are successfully prepared by the transesterification of alkyl halo‐esters with PEGs using Candida antarctica lipase B (CALB) as a biocatalyst under the solventless conditions. Transesterifications of chlorine, bromine, and iodine esters with tetraethylene glycol monobenzyl ether (BzTEG) are quantitative in less than 2.5 h. The transesterification of halo‐esters with PEGs are complete in 4 h. ¹H and ¹³C NMR spectroscopy with MALDI‐ToF and ESI mass spectrometry confirm the structure and purity of the products. This method provides a convenient and “green” process to effectively produce halo‐ester PEGs.

     

Synthesis and characterization of water‐soluble barbiturate‐ and thiobarbiturate‐functionalized polystyrene

The synthesis and characterization of barbiturate‐ and thiobarbiturate‐functionalized polystyrene from polystyrene homopolymer by polymer‐modification reactions is discussed. Polystyrene homopolymer quantitatively functionalized at the para postion with diethyl oxomalonate functionality was subjected to a condensation reaction with urea and thiourea in the presence of sodium methoxide in methanol. This reaction proceeded essentially to quantitative conversion to the barbiturate‐ (BAPS) and thiobarbiturate‐functionalized polystyrenes (TBAPS) as estimated by ¹H NMR, UV, and IR spectroscopies. Thus, several copolymers of styrene with barbiturate‐ and thiobarbiturate‐functionalized styrene were synthesized. The detailed characterizations of quantitatively functionalized polystyrene using gel permeation chromatographic, IR, UV, and ¹H NMR spectroscopic techniques as well as thermogravimetric analysis are discussed. An application of the newly synthesized polymer in removing Cu(II) ions from aqueous solution is demonstrated. This is the first report on the synthesis of BAPS and TBAPS by the polymer‐modification route or otherwise. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 731–737, 2002; DOI 10.1002/pola.10154     

Signatures of a Concentration‐Dependent Flory χ Parameter: Swelling and Collapse of Coils and Brushes

The quality of solvents of polymers is often described in terms of the Flory χ parameter typically assumed to depend only on the temperature, T. In certain polymer‐solvent systems fitting the experimental data enforces the replacement of (χT) by a concentration‐dependent χ_eff. In turn, this modifies the swelling and collapse behavior. These effects are studied, in the framework of a mean‐field theory, for isolated coils and for planar brushes. The ϕ dependence of χ_eff gives rise to three main consequences: (i) shift in the cross‐over between Gaussian and self‐avoidance regimes; (ii) a possibility of first‐order collapse transition for isolated flexible coils; (iii) the possibility of a first‐order phase transition leading to a vertical phase separation within the brush. The discussion relates these effects directly to thermodynamic measurements and does not involve a specific microscopic model. The implementation for the case of poly(N‐isopropylamide) (PNIPAM) brushes is discussed.

ϕ vs. z plots, for brushes with N = 300, σ/a² = 18 (σ/R = 0.019) characterized by different χ_eff.