Synthesis and characterization of novel pH-responsive microgels based on tertiary amine methacrylates

Emulsion polymerization of 2-(diethylamino)ethyl methacrylate (DEA) in the presence of a bifunctional cross-linker at pH 8-9 afforded novel pH-responsive microgels of 250-700 nm diameter. Both batch and semicontinuous syntheses were explored using thermal and redox initiators. Various strategies were evaluated for achieving colloidal stability, including charge stabilization, surfactant stabilization, and steric stabilization. The latter proved to be the most convenient and effective, and three types of well-defined reactive macromonomers were examined, namely, monomethoxy-capped poly(ethylene glycol) methacrylate (PEGMA), styrene-capped poly[2-(dimethylamino)ethyl methacrylate] (PDMA50-St), and partially quaternized styrene-capped poly[2-(dimethylamino)ethyl methacrylate] (10qPDMA50-St). The resulting microgels were pH-responsive, as expected. Dynamic light scattering and 1H NMR studies confirmed that reversible swelling occurred at low pH due to protonation of the tertiary amine groups on the DEA residues. The critical pH for this latex-to-microgel transition was around pH 6.5-7.0, which corresponds approximately to the known pKa of 7.0-7.3 for linear PDEA homopolymer. The microgel particles were further characterized by electron microscopy and aqueous electrophoresis studies. Their swelling and deswelling kinetics were investigated by turbidimetry. The PDEA-based microgels were compared to poly[2-(diisopropylamino)ethyl methacrylate] (PDPA) microgels prepared with identical macromonomer stabilizers. These PDPA-based microgels had a lower critical swelling pH of around pH 5.0-5.5, which correlates with the lower pKa of PDPA homopolymer. In addition, the kinetics of swelling for the PDPA microgels was somewhat slower than that observed for PDEA microgels; presumably this is related to the greater hydrophobic character of the former particles.     

Synthesis and characterization of pH-responsive diblock copolymers with cadaverine side groups

In this paper, we report the synthesis and characterization of a new pH-responsive diblock copolymer, methoxy poly(ethylene glycol)-b-poly[N¹-(4-vinylbenzyl) pentane-1,5-diamine dihydrochloride] (mPEG-b-PVBPDA). The monomer with cadaverine side group (N¹-(4-vinylbenzyl)pentane-1,5-diamine dihydrochloride, VBPDA) and the macroinitiator (mPEG-ACVA) were synthesized, respectively, and mPEG-b-PVBPDA was then obtained by free radical polymerization. The structure and molecular weight of mPEG-b-PVBPDA was confirmed by FTIR, ¹H NMR, and GPC-MALLS measurements. At low pH, it is hydrophilic due to the protonation of the amine groups. With increasing pH, deprotonation occurs, and the hydrophobicity of PVBPDA block increases. This molecular feature leads to interesting aggregation behavior of mPEG-b-PVBPDA in aqueous solutions at different pH as revealed by DLS measurements, TEM observations, and fluorescence spectrometry. This polymer was further subjected to gene delivery evaluations, and promising DNA transfection capacity has been found.     

Synthesis,characterization, and thermal and dielectric properties of three different methacrylate polymers with zwitterionic pendant groups

The synthesis, characterization, thermal, and dielectric properties of three different zwitterionic methacrylates of the sulfobetaine type are presented. Diethylamine-ethyl-, 2-(diethylaminoethoxy)-ethyl-, and 2-(2-diethylaminoethoxy) ethoxy-ethyl-methacrylates were made to react with butanosultone to prepare monomers with variable flexibility. The flexibility of the lateral chain of the polymethacrylates decreased the glass transition temperature (T_g down to 300 K) of the polymers. A linear relationship between T_g and the number of carbon atoms was shown for these materials. X-ray diffraction and DSC experiments showed the formation of new ordered phases in these polymers, which inhibited their dipole conductivity. On heating, these phases were destroyed and values of conductivity of 10⁻⁷–10⁻³ S cm⁻¹ were obtained in the studied range of temperature. Variation of conductivity with temperature was established according to the Arrhenius equation. Dielectric properties exhibited a small deviation of the Debye type behavior, and β parameters of the Cole–Cole equations were calculated for the synthesized polymers. © 1997 John Wiley & Sons, Inc.     

两性离子表面活性剂的合成及其表面性质

合成了一类含季铵基和磺酸基结构的非对称Gemini两性离子表面活性剂;利用红外光谱、质谱、离子定性试验验证了合成产物的分子结构,并测定了其表面性质.结果表明,目标产物的分子结构符合设计预期;五种非对称Gemini两性离子表面活性剂的表面张力在30mN/m左右,临界胶束浓度达到10-4~10-5数量级.此外,虽然非对称Gemini两性离子表面活性剂的起泡性能比相应单链型表面活性剂的稍差,但其稳泡性明显优于后者.     

Synthesis,characterization and memory properties of novel organosoluble polyimides

Two novel series of aromatic polyimides were prepared from 2,2′‐bis(4‐amino‐3‐trifluoromethylthylphenoxy) biphenyl, 2,2′‐bis(4‐amino‐3‐methoxyphenoxy)biphenyl with 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA), 3,3′,4,4′‐diphenylsulfonetetracarboxylic dianhydride (DSDA) via a one‐step procedure. The resulting polymers were fully characterized, and they exhibited excellent organosolubility. These polyimides are thermally stable with 5% weight loss over 430°C, and glass transition temperatures of the polyimides were found to be 225–262°C. Resistive switching devices with the configuration of Al/polymer/indium‐tin oxide were constructed from these polyimides by using conventional solution coating process. Devices with all polyimides exhibited nonvolatile and rewritable flash type memory characteristics with turn‐on voltage at ?1.1 to ?2.8 V. The ON/OFF current ratio of these devices was larger than 10⁴, and the retention times can be as long as 10⁴ s. The theoretical simulation based on the density functional theory suggested that greater distinct charge separation between the ground and charge transfer states led to a highly stable memory behavior. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis, characterization and properties of a novel fluorinated polyurethane

A novel fluorinated polyurethane (FPU) was prepared by fluorinated polyether glycol (PTMG-g-HFP) as a soft segment, 1,6-hexamethylene diisocyanate (HDI) or toluene diisocyanate (TDI) as a hard segment and 1,4-butanodiol (BDO) as a chain extender. Fourier transform infrared spectroscopy (FTIR), ¹H NMR, ¹³C NMR and gel permeation chromatography (GPC) were used to characterize the structure of the fluorinated polyurethane. The thermal stabilities of the fluorinated polyurethane and the corresponding hydrogenated polyurethane were studied by thermogravimetric analysis (TGA). X-ray photoelectron spectroscopy (XPS) analysis at two different sampling depths for the fluorinated polyurethane was used to investigate the surface compositions of FPU. And the mechanical properties of the fluorinated polyurethane and the corresponding hydrogenated polyurethane were also measured. Chemical resistance of polyurethane films was estimated through spot tests with different solvents. The results showed that FPU had high thermal stability, strain-hardening property and good chemical resistance. The XPS measurements showed the fluorine enrichment on the surface of FPU.     

Synthesis, characterization and FET properties of novel dithiazolylbenzothiadiazole derivatives

Dithiazolylbenzothiadiazoles easily obtained have high electron affinity and the FET device of a trifluoromethylphenyl derivative exhibited a good n-type performance with high electron mobility.     

新型偶氮苯金属液晶化合物的合成与性能研究

合成了新型偶氮苯金属配合物。 分别采用光谱分析、热分析及X射线衍射测试技术对样品进行了表征。结果表明,连接偶氮苯和金属配合物之间碳链的长度对该化合物的相转变和荧光特性具有特殊的影响。 该系列化合物在紫外光和热作用下具有99%以上的偶氮苯顺-反异构化反应效率;具有290和560 nm这2个波段荧光发射光谱。由其中一个金属液晶化合物分散在聚甲基丙烯酸甲酯网络而形成的介质可作为全息信息存储材料而实现全息图像的写入和读出。     

Synthesis and characterization of oligomaltose-grafted lipids with application to liposomes

Novel glycolipids, which contain 2 and 15 oligomaltose units and a phosphatidylethanolamine, were synthesized and characterized by FTIR and (1)H-NMR spectroscopies. The well-defined linear structure of the glycolipids was assured by an end-point conjugation strategy using selective oxidation of the reducing end groups of maltose oligosaccharides, followed by aminolysis with distearoylphosphatidylethanolamine. The intermediate acids react selectively with amines to form amide linkages, catalyzed by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide. Conformations of the glycolipids at the air-water interface were proposed based on the film balance measurements. The unique conformations of glycolipids at interfaces may offer advantages over traditional PEO-derived lipids in regard to their applications for sterically stabilizing liposomes. The glycolipids demonstrated the ability for sterically stabilizing liposome dispersions, as determined by turbidity measurements.     

Synthesis and aqueous solution properties of sterically stabilized pH-responsive polyampholyte microgels

Emulsion copolymerization of poly(methacrylic acid) and poly(2-(diethylamino)ethyl methacrylate) (PMAA/PDEA) yielded pH-responsive polyampholyte microgels of 200-300 nm in diameter. These microgels showed enhanced hydrophilic behavior in aqueous medium at low and high pH, but formed large aggregates of approximately 2500 nm at intermediate pH. To achieve colloidal stability at intermediate pH, a second batch of microgels of identical monomer composition were synthesized, where monomethoxy-capped poly(ethylene glycol)methacrylate (PEGMA) was grafted onto the surface of these particles. Dynamic light-scattering measurements showed that the hydrodynamic radius, Rh, of sterically stabilized microgels was approximately 100 nm at intermediate pH and increased to 120 and 200 nm at pH 2 and 10, respectively. Between pH 4 and 6, these microgels possessed mobility close to zero and a negative second virial coefficient, A2, due to overall charge neutralization near the isoelectric pH. From the Rh, mobility, and A2, cross-linked MAA-DEA microgels with and without PEGMA retained their polyampholytic properties in solution. By varying the composition of MAA and DEA in the microgel, it is possible to vary the isoelectric point of the colloidal particles. These new microgels are being explored for use in the delivery of DNA and proteins.     

Synthesis and biophysical characterization of oligonucleotides containing a 4'-selenonucleotide

The first synthesis of oligonucleotides containing 4'-selenium-modified ribonucleotides (4'-Se-rN) is described. Four sequences containing 4'-Se-rT were successfully synthesized and compared with DNA and RNA oligonucleotides containing a dT, rT, or LNA insert in place of the 4'-Se-rT. The 4'-Se-rT behaved more like rT than dT in its effects on binding affinity, despite the DNA-like structure previously observed for the nucleoside, suggesting that a conformational switch occurs upon incorporation into an oligonucleotide. Incorporation of 4'-Se-rT into A-RNA and hybrid duplexes led to increased binding affinity, while incorporation into B-DNA destabilized the duplex to the same extent as an rT nucleotide.     

Synthesis, characterization and properties of a novel fluorinated methacrylate polymer

A fluorinated monomer of 2-(2,2,2-trifluoroethoxy)ethyl methacrylate (FEMA) was prepared by a “one pot” process and then a novel fluorinated methacrylate polymer, poly[2-(2,2,2-trifluoroethoxy)ethyl methacrylate] (PFEMA), was successfully synthesized via miniemulsion polymerization using cetyltrimethyl ammonium bromide (CTAB) as emulsifier, hexadecane (HD) as co-stabilizer and 2,2′-azobisisobutyronitrile (AIBN) as initiator. The chemical structure of PFEMA was characterized by FT-IR, ¹H NMR and ¹⁹F NMR. GPC results show that the number average molecular weight (M_n) of PFEMA was as high as 8.5 × 10⁵ g/mol and the polydispersity index (PDI) was only 1.3. SEM and DLS characterizations showed that the morphology of PFEMA latex was uniform spheres with the diameter of about 110–125 nm. It was also found that PFEMA has high thermo-stability (T_d > 200 °C), low glass transition temperature (T_g = 13.0 °C), and nice hydrophobicity (θ_water = 99.9°). Comparison studies on PFEMA and poly(2,2,2-trifluoroethyl methacrylate) show that an introduced functional group (–CH₂CH₂O–) has a significant effect on lowering T_g and improving hydrolysis resistance without impairing surface properties.     

Synthesis,characterization, and properties of novel aromatic bispropenyl ethers

Aromatic bispropenyl ethers are a new class of highly reactive thermosetting monomers that have been prepared and characterized. Two synthetic routes to their preparation have been developed. The first of these involves the base-catalyzed isomerization of bisallyl ether precursors that gives predominantly the Z bispropenyl ether isomers. The second method employs tris(triphenylphosphine)ruthenium(II) dichloride as an isomerization catalyst and produces predominantly the E isomers. Using these methods, a number of bispropenyl ether monomers containing different aromatic groups have been synthesized. The cationic polymerization of these novel monomers to give crosslinked network polymers using diaryliodonium salts as photo and thermal initiators has been studied.     

Synthesis, characterization and photocatalytic properties of novel zinc germanate nano-materials

We report the first instance of a hydrothermal synthesis of zinc germanate (Zn₂GeO₄) nano-materials having a variety of morphologies and photochemical properties in surfactant, template and catalyst-free conditions. A systematic variation of synthesis conditions and detailed characterization using X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, Raman spectroscopy, electron microscopy, X-ray photoelectron spectroscopy and small angle X-ray scattering led to a better understanding of the growth of these particles from solution. At 140 °C, the zinc germanate particle morphology changes with pH from flower-shaped at pH 6.0, to poly-disperse nano-rods at pH 10 when the Zn to Ge ratio in the synthesis solution is 2. When the Zn to Ge ratio is reduced to 1.25, mono-disperse nano-rods could be prepared at pH 7.5. Nanorod formation is also independent of the addition of cetyltrimethylammonium bromide (CTAB), in contrast to previous reports. Photocatalytic tests show that Zn₂GeO₄ nano-rods (by weight) and flower shaped (by surface area) are the most active for methylene blue dye degradation among the synthesized zinc germanate materials.     

Synthesis and characterization of novel fluorinated thermoplastic polyurethane with high transmittance and superior physical properties

Three novel series of transparent fluorinated thermoplastic polyurethane (FTPU) elastomers based on 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI), polytetramethylene glycol (PTMG), polycaprolactone (PCL) and 4,4′-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene] bisphenol (BPAF) were synthesized by two-step solution polymerization. The FTPU were characterized by Fourier transform infrared spectrometry (FTIR), UV-Visible spectrometry (UV-Vis), wide angle X-ray diffraction (WAXD), atomic force microscopy (AFM), thermogravimetric analysis (TGA), and mechanical tests. The FTIR results indicate that the micro-phase separation and hydrogen bonding strength increase with increasing fluorine content, which are proved by the results of AFM and WAXD. The UV-Vis tests show high transmittance of FTPU films which is affected by crystallization easily. The TGA and mechanical tests indicate that thermal stability and mechanical properties of FTPU are improved significantly with the introduction of BPAF.     

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.     

近红外电致变色胆甾相液晶高分子的设计、合成及旋光开关性质

通过单体4′-甲氧基苯基-4-烯丙氧基苯甲酸酯(M1)、(S)-(-)-N-(5-己烯基)-6-(4′-(2-甲基丁氧基)苯基)-蒽醌-2,3-二羧酸酰亚胺(M2)与聚甲基氢硅氧烷间的硅氢加成反应,制得了3个新的具有近红外电致变色性质的侧链型液晶共聚物(PC5A10,PC5A20CB,PC5A30CB),并对其液晶性,电化学,光谱电化学和旋光开关性质进行了表征.当M2单体的含量为10mol%,20mol%时,共聚物可形成胆甾相液晶,而当其含量为30mol%时,所能形成的液晶相为近晶A相.3个共聚物的循环伏安曲线均出现了两对可逆的氧化还原峰,分别对应于蒽醌酰亚胺基团得电子而形成自由基阴离子和二价阴离子.中性态时,共聚物在420nm处有较强吸收,而当被还原为自由基阴离子后,在近红外区域840nm出现了新的强烈的吸收.以聚合物为阴极电致变色层,普鲁士蓝为离子储存层的全固态电致变色器件在800nm有较好的光学调制性.此外,本文还就该器件的电化学调控手性光开关性质进行了初步研究.     

Synthesis and characterizations of a novel zwitterionic hybrid copolymer containing both sulfonic and carboxylic groups via sulfonation and zwitterionic process

A novel zwitterionic hybrid copolymer containing both sulfonic and carboxylic groups was synthesized via sulfonation, zwitterionic process and sol-gel reaction. The properties of the step products were characterized by FT-IR spectra, thermal analyses, MALDI measurements and SEM morphologies. FT-IR spectra confirmed the related reactions. TGA and DrTGA analyses showed that their thermal stability enhanced with an increase in the zwitterionic extent. DSC curves revealed that both the glass transition temperature and the melting temperature elevated with the rising content of ion pairs. MALDI measurements suggested that the molecular structure of the zwitterionic hybrid PEG-[Si(OEt)₃]₂SO₃HCOOH was more stable than that of neutral hybrid PEG-[Si(OEt)₃]₂ or that of negatively charged hybrid PEG-[Si(OEt)₃]₂SO₃H. SEM image of the sulfonated polymer film indicated that the pore size was within 2.4-6.1 μm; whereas SEM of the zwitterionized copolymer film displayed that its pore size was less than 1 μm. This shrinkage in pore size can be ascribed to the introduction of carboxylic groups into the copolymer chains. Compared with that observed in the unionized polymer film, the large difference in the morphology of the ionized copolymer films demonstrated that ionization could alter these copolymer’s characteristics. Due to its excellent pore-creating performance, this zwitterionic hybrid copolymer expects to be employed to prepare nanofiltration and ultrafiltration membranes.     

Synthesis,characterization, and physical properties of two novel nonaheteroacene derivatives

Two novel nonaheteroacene derivatives: 24,27,30,33-tetra-tert-butyl-6,8,10,17,19,21-hexaaza-1.22,4.5,11.12,15.16-tetrabenzono-nonaacene (1) and 24,27,30,33-tetra-tert-butyl-6,10,17,21-tetraaza-8,19-benzodioxin-1.22,4.5,11.12,15.16-tetrabenzono-nonaacene (2), have been successfully synthesized through cyclocondensation reactions. The studies on UV–vis and cyclic voltammogram suggest that compound 1 has a smaller bandgap comparing to that of compound 2, indicating that oxygen atoms can destroy the conjugation in compound 2. The results are further confirmed by theoretical simulation.     

Synthesis, characterization and photophysical properties of novel tetrasubstituted phthalocyaninato zinc derivatives

Peripherally tetraimido-substituted phthalocyaninato zinc compounds 1-3 were synthesized through the reaction of tetraamino-substituted phthalocyaninato zinc with 4-Br-1,8-naphthalic anhydride, 4-hexahydropyridine-1,8-naphthalic anhydride and 4-morpholine-1,8-naphthalic anhydride, respectively. The compounds were characterized by MS, ¹H NMR, UV-vis, IR and elemental analysis, the results of which were consistent with the proposed structures. The effects of substitutes, acid/base and solvents on the UV-vis spectra of the new complexes were discussed in detail.