pH响应性阿维菌素/介孔硅的一步合成与释放

以三嵌段共聚物F127（(EO)106(PO)70(EO)106）为模板剂,正硅酸甲酯（TMOS）为硅源,阿维菌素(AVM)为模型药物,通过一步法合成载药介孔硅材料(HOMS),采用铜、锌、锰3种金属离子改性,形成具有pH响应性的缓释材料AVM/Zn-HOMS、AVM/Cu-HOMS和AVM/Mn-HOMS,借助FTIR、SEM、N2吸附-脱附法和TGA表征了缓释材料,并研究了其在不同pH下的释放行为。结果表明,AVM/Zn-HOMS、AVM/Cu-HOMS和AVM/Mn-HOMS材料表面分别呈现层状、疏松多孔状以及气泡状结构,比表面积分别为308.581、101.218和318.011 m2/g,氮气吸附-脱附等温线类型为具有H2型滞后环的Langmuir Ⅳ型。AVM/Zn-HOMS和AVM/Cu-HOMS呈现良好的pH响应性,AVM/Mn-HOMS则未表现出明显的pH响应性,3种材料的缓释行为均可用Higuchi动力学模型描述,释放过程受扩散机制控制。     

Synthesis and characterization of pH/temperature-sensitive block copolymers via atom transfer radical polymerization

In order to prepare well-defined pH-sensitive block copolymers with a narrow molecular weight distribution (MWD), we synthesized a pH-sensitive block copolymer via atom transfer radical polymerization (ATRP) of sulfamethazine methacrylate monomer (SM) and amphiphilic diblock copolymers by the ring-opening polymerization of d,l-lactide/?-caprolactone (LA/CL), and their sol-gel phase transition was investigated. SM, which is a derivative of sulfonamide, was used as a pH responsive moiety, while PCLA-PEG-PCLA was used as a biodegradable, as well as a temperature sensitive one, amphiphilic triblock copolymer. The pentablock copolymer, OSM-PCLA-PEG-PCLA-OSM, was synthesized using Br-PCLA-PEG-PCLA-Br as an ATRP macroinitiator. The number average molecular weights of SM were controlled by adjusting the monomer/initiator feed ratio. The macroinitiator was synthesized by the coupling of 2-bromoisobutyryl bromide with PCLA-PEG-PCLA in the presence of triethyl amine catalyst in dichloromethane. The resultant block copolymer shows a narrow polydispersity. The block copolymer solution shows a sol-gel transition in response to a slight pH change in the range of 7.2-8.0. Gel permeation chromatography (GPC) and NMR were used for the characterization of the polymers that were synthesized.     

聚苯乙烯-聚硅氧烷接枝共聚物的合成与表征

以甲基丙烯酰氧丙基聚硅氧烷大单体(PDMS-MA)与苯乙烯共聚合,制备了聚苯乙烯-聚硅氧烷梳状接枝共聚物（PSt-g-PDMS）,采用傅里叶变换红外光谱（FTIR）表征了接枝共聚物的组成,研究了聚硅氧烷大单体的相对分子质量对共聚合活性的影响,并对接枝共聚物的热性能进行了表征.结果表明,大单体PDMS-MA的共聚合活性随其相对分子质量的增大而减小,随投料比的增加,共聚合转化率下降.与纯聚苯乙烯相比,PSt-g-PDMS的热稳定性提高.而且,随着大单体PDMS-MA相对分子质量和它在共聚物中含量的增加,接枝共聚物的热稳定性增加.     

Synthesis of PEGylated poly(amino acid) pentablock copolymers and their self‐assembly

Pentablock copolymers with an ABCBA architecture were synthesized by ring‐opening polymerization of N‐carboxyanhydrides of l ‐leucine and γ‐benzyl l ‐glutamate using an α, ω‐diamino poly(ethylene glycol) (PEG) as macroinitiator. Three different PEGs with molecular weights of 2000, 4600 and 10 000 Da were used and the poly(amino acid) (PAA) block lengths were set to a combined 10 and 40, respectively, repeat units for p(l ‐Leu) and 40 repeat units for p(l ‐Glu). The molecular architecture of the resulting pentablock copolymers was determined by the order of monomer addition. The living character of the N‐carboxyanhydride ring‐opening polymerization enables the formation of multiblock copolymers. The degree of polymerization for the PAA blocks matched the monomer/initiator ratio. A structural switch element, which controls the hydrophilicity of the pentablock copolymers, was incorporated in the form of the p(l ‐Glu) blocks. The pentablock copolymers became water soluble after hydrolyzing the benzyl ester protective groups. The pentablock copolymers self‐assembled into polymeric aggregates ranging in size between 160 and 340 nm. Hydrogels formed readily if the central PEG block had a molecular weight of at least 4600 Da and the terminal A‐blocks consisted of p(l ‐Leu). SEM images confirmed the size ranges of the polymeric aggregates and showed non‐distinct spherical aggregates. © 2016 Society of Chemical Industry     

Synthesis and characterization of silicon-containing graft copolymers

Poly(4-t-butoxycarbonyloxystyrene)-g-poly(dimethylsiloxane) and poly(t-butylmethacrylate)-g-poly(dimethylsiloxane) with various chemical compositions were synthesized via free radical polymerization of 4-t-butoxycarbonyloxystyrene (TBCS) or t-butylmethacrylate (TBMA) with silicone macromers. These macromers were prepared by anionic ring-opening polymerization of hexamethylcyclotrisiloxane (D₃) and subsequent termination with a chlorosilane compound having a methacrylate functionality. The morphology of the graft copolymer systems was investigated by DSC and TEM.     

Synthesis and characterization of polyoxazoline-polysulfone triblock copolymers

Amphiphilic triblock poly(2-ethyl-2-oxazoline-b-sulfone-b-2-ethyl-2-oxazoline) (PEOX-b-PSF-b-PEOX) and poly(2-ethyl-2-oxazoline-co-ethyleneimine-b-sulfone-b-2-ethyl-2-oxazoline-co-ethyleneimine) (PEOXcoPEI-b-PSF-b-PEOXcoPEI) copolymers were synthesized for potential use as water purification membranes. Poly(arylene ether sulfone) (polysulfone) oligomers of controlled molecular weight were prepared by nucleophilic step polymerization of 4,4′-dichlorodiphenyl sulfone with a molar excess of bisphenol-A. The phenolate endgroups were then reacted with ethylene carbonate to afford telechelic aliphatic hydroxyethyl groups. These were tosylated to produce macroinitiators for ring-opening cationic polymerization of 2-ethyl-2-oxazoline. Subsequently, the pendent amides on the hydrophilic PEOX blocks were also hydrolyzed to generate positively charged PEOXcoPEI-b-PSF-b-PEOXcoPEI copolymers. Compositions with high polysulfone compositions relative to the hydrophilic blocks were of particular interest because they maintained good mechanical integrity in water. Water uptake at room temperature increased up to 18 wt% for copolymers with 22 wt% of the hydrophilic components. Solid-state thermal properties suggested some phase mixing of the components in the PEOX-b-PSF-b-PEOX copolymers but better phase separation of the blocks in the partially hydrolyzed PEOXcoPEO-b-PSF-b-PEOXcoPEI materials.     

Synthesis and characterization of ethyl methacrylate-acrylamide copolymers

Free radical copolymerization of ethyl methacrylate (EMA) and acrylamide (AA) was carried out in the presence of 2,2′-azobisisobutyronitrile (AIBN) in dimethyl formamide (DMF) at 60°C. The percentage composition of the copolymers were established by elemental analysis. The copolymerization reactivity ratios were determined by both Fineman-Ross (F-R) and Kelen-Tudos (K-T) methods. The copolymers were characterized by IR, ¹H-NMR, thermal, and dielectric studies. Glass transition temperatures (T_g) have been determined by DSC. The solubility parameter of this copolymer was evaluated by studying the intrinsic viscosity in different solvents.     

Synthesis and characterization of nylon-polyisobutylenenylon triblock copolymers

Nylon-6-polyisobutylene-nylon-6 triblock copolymers have been synthesized by converting telechelic polyisobutylene diols to , -diisocyanate polyisobutylenes and using these macroactivators, in conjunction with strong base, to induce the subsequent anionic polymerization of -caprolactam. Pure block copolymer was obtained by suitable sequential extraction. Products were characterized by composition, molecular weight and DSC.     

梳状聚苯乙烯-聚二甲基硅氧烷共聚物的合成及表征

通过苯乙烯与聚二甲基硅氧烷大单体进行自由基聚合反应,合成了梳状聚苯乙烯-聚二甲基硅氧烷共聚物.结果表明,侧链聚二甲基硅氧烷的相对分子质量越大,梳状聚苯乙烯-聚二甲基硅氧烷共聚物的相分离程度越明显,其热稳定性与聚苯乙烯相比有一定程度的提高.     

Synthesis and electrochemical characterization of PEO-based polymer electrolytes with room temperature ionic liquids

New gel polymer electrolytes containing 1-butyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide (BMPyTFSI) ionic liquid are prepared by solution casting method. Thermal and electrochemical properties have been determined for these gel polymer electrolytes. The addition of BMPyTFSI to the P(EO)₂₀LiTFSI electrolyte results in an increase of the ionic conductivity, and at high BMPyTFSI concentration (BMPy⁺/Li⁺ = 1.0), the ionic conductivity reaches the value of 6.9 × 10⁻⁴ S/cm at 40 °C. The lithium ion transference numbers obtained from polarization measurements at 40 °C were found to decrease as the amount of BMPyTFSI increased. However, the lithium ionic conductivity increased with the content of BMPyTFSI. The electrochemical stability and interfacial stability for these gel polymer electrolytes were significantly improved due to the incorporation of BMPyTFSI.     

Synthesis and characterization of copolymers of styrene andN-methylolacrylamide

Copolymers of styrene (ST) and N-methylolacrylamide (NMA) were synthesized by emulsion polymerization for different initial weight ratios of ST/NMA. Fast reaction rates and high conversions are achieved regardless of the ST/NMA ratio. NMA content in copolymers, as deduced by DSC, FTIR and Kjeldhal analysis, is higher as the initial ST/NMA ratio decreases. Glass transition temperature of copolymers increases as the ST/NMA ratio decreases and it decreases with reaction time for a fixed ST/NMA ratio. The latter results and FTIR spectra as well as Kjeldhal analysis as a function of reaction time indicate that NMA reacts initially in the aqueous phase, after which ST, because of its overall larger concentration, is incorporated preferentially in the polymer.     

Synthesis and characterization of functionalized syndiotactic polystyrene copolymers

Functionalized syndiotactic polystyrene copolymers were synthesized and characterized. The syndiotactic polystyrene copolymers, poly(styrene‐co‐4‐methylstyrene) (sPSMS), were prepared by styrene with 4‐methylstyrene with a metallocene/methylaluminoxane catalyst. In addition, grafted copolymers, chemically grafted with isoprene onto an sPSMS backbone [poly(styrene‐co‐4‐methylstyrene)‐g‐polyisoprene (sPSMS‐g‐PIP)] were synthesized by anionic grafting polymerization with a metallation reagent. In this study, we also examined the effect of the degree of functionalization (epoxidation) on the polymer structure of the sPSMS‐g‐PIP copolymers. Experimental results indicate that the crystallinity of the sPSMS‐g‐PIP copolymer was lower than that of the ungrafted sPSMS copolymer. Moreover, the epoxy‐containing sPSMS‐g‐PIP copolymer effectively increased the thermal stability more than did the sPSMS‐g‐PIP copolymer alone. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1038–1045, 2002     

Synthesis and characterization of phenylene-thiophene all-conjugated diblock copolymers

Grignard metathesis (GRIM) polymerization for all-conjugated diblock copolymers comprising poly(2,5-dihexyloxy-1,4-phenylene) (PPP) and poly(3-hexylthiophene) (P3HT) blocks were systematically studied with LiCl as additive and 1,2-bis (diphenylphosphino) ethane nickel dichloride (Ni(dppe)Cl₂) or 1,3-bis(diphenylphosphino) propane nickel dichloride (Ni(dppp)Cl₂) as catalyst. It was found that the addition order of the monomers was crucial for the success of copolymerization. With the monomer addition in the order of phenyl and then thienyl Grignard reagents, all-conjugated PPP-b-P3HT diblock copolymers with different block ratios were successfully synthesized. In contrast, the inverted addition order only afforded a mixture containing both block copolymers and deactivated or end-capped homopolymers. Mass spectroscopic analysis indicates that the effect of the addition order of the monomers on copolymerization is attributed to the low efficiency of intramolecular Ni transfer from thiophene to phenylene units. The resulting PPP-b-P3HT diblock copolymers were characterized by differential scanning calorimetry (DSC) and atomic force microscopy (AFM). It was found that both PPP and P3HT blocks in the copolymers were crystalline, and microphase separation between them took place, as indicated by two endothermal transitions corresponding to the melting of PPP and P3HT blocks, respectively. These unique properties may render PPP-b-P3HT diblock copolymers potential applications in optoelectronics.     

Synthesis and characterization of thermo-responsive supramolecular diblock copolymers

In this paper, we report the synthesis and characterization of a new thermo-responsive supramolecular amphiphiles diblock copolymer, methoxy poly (ethylene glycol)-block-Poly(N-isopropylacrylamide) (mPEG-b-PNIPAM). The mPEG with β-cyclodextrin (β-CD) group and the PNIPAM with adamantine (AD) group were synthesized, respectively, and mPEG-b-PNIPAM was then obtained by the host-guest inclusion between AD and β-CD. The structure and molecular weight of mPEG-b-PNIPAM was confirmed by ¹H NMR and GPC measurements. At low temperature (T?<?33 °C), the PNIPAM block is hydrophilic. With increasing temperature, the hydrophobicity the of PNIPAM block increases. This molecular feature leads to interesting aggregation behavior of micelles in aqueous solutions at different temperatures. The self-assembly was revealed by UV, DLS measurements, and TEM observations.     

Synthesis and characterization of phenylquinoxaline-arylene ester block copolymers

Summary Phenylquinoxaline-arylene ester block copolymers were prepared from phenolic hydroxyl terminated oligomers of defined molecular weight using an oligomer/monomer(s) approach, in which generation of the ester linkage coupling the blocks occurred concomitantly with the growth of the polyester block. The molecular weight of the phenylquinoxaline block was held constant at 12,900, while the stoichiometry of the arylene ester monomers were adjusted to afford copolymers containing 15, 30, and 50 wt% poly(arylene ester). These copolymers represent the first example of PPQ-based block copolymers derived from well defined phenylquinoxaline oligomers.     

Synthesis and characterization of waterborne polyurethane acrylate copolymers

Polyurethane acrylate copolymers were synthesized by emulsion polymerization process. To reduce the environmental hazards, organic solvents were replaced by eco-friendly aqueous system. Concentration of polyurethane and acrylate monomer was varied to investigate the effect of chemical composition on performance properties of copolymers. FTIR spectroscopy was used as a key tool to record the chemical synthesis route. The synthesized copolymer emulsions were characterized by evaluating their particle size, viscosity, dry weight content, chemical and water resistance. Thermal decomposition was studied by thermogravimetric analysis. Scanning electron microscope was used to visualize the morphological structure of copolymers. The experimental results indicate better polyurethane acrylate compatibility till the ratio of 30/70. However, these copolymers exhibited synergistic effects between the two polymers and revealed a remarkable improvement in numerous coating properties.