Synthesis and thermally responsive characteristics of dendritic poly(ether-amide) grafting with PNIPAAm and PEG

A series of thermally responsive dendritic core-shell polymers were prepared based upon dendritic poly(ether-amide) (DPEA), modified with carboxyl end-capped linear poly(N-isopropylacrylamide) (PNIPAAm-COOH) or both PNIPAAm-COOH and carboxyl end-capped methoxy polyethylene glycol (PEG-COOH) in different ratios via an esterification process to obtain DPEA-PNIPAAm or DPEA-PNIPAAm-PEG. Their molecular structures were verified by gel permeation chromatography, and ¹H NMR and FTIR spectroscopy. The temperature-dependent characteristics study has revealed that DPEA-PNIPAAm exhibits a lower critical solution temperature (LCST) of about 34 °C, whereas DPEA-PNIPAAm-PEG polymers with the PNIPAAm/PEG ratio of about 1.0 and 0.4 possess about 36 °C and 39 °C, respectively, compared with 32 °C for homopolymer PNIPAAm. The critical aggregation temperature was investigated using fluorescence excitation spectrum of pyrene as a sequestered guest molecule based upon the sharp increase of the I₃₃₈/I₃₃₃ value.     

High Aspect Ratio Polymeric Nanoneedle Arrays

High aspect ratio (HAR) nanoneedle arrays can be used to tune the intrinsic properties of substrates such as their wettability and reflectivity. Here, a simple and scalable fabrication method for producing dense arrays of freestanding polyethylene glycol (PEG) nanoneedles with sub 50 nm tips and surface coverage up to 83 needles per µm² is presented. Two distinct sets of silicon nanoneedle master arrays with base diameters between 15 and 265 nm and heights between 146 and 613 nm are fabricated using block copolymer micelle lithography. Replication of selected silicon masters using photocurable polymers produces HAR PEG nanoneedle arrays with feature base diameters ranging between 15 and 292 nm and heights between 133 and 656 nm. At their maximum, the aspect ratio of the pillars is 4.6. PEG nanoneedle arrays are produced using polymers with two different molecular weights as well as two different photoinitiators, showing the versatility of the process.     

Synthesis and Surface Activities of Novel Succinic Acid Monofluoroalkyl Sulfonate Surfactants

Two environmentally friendly succinic acid monofluoroalkyl sulfonate surfactants were synthesized from maleic anhydride and polyethylene glycol mono (1H,1H,7H‐dodecafluoroheptyl) ether, i.e. H(CF₂)₆CH₂OCH₂CH₂OCOCH(SO₃Na)CH₂COOH (FEOS‐1) and H(CF₂)₆CH₂(OCH₂CH₂)₃OCOCH(SO₃Na)CH₂COOH (FEOS‐3). The obtained surfactants were characterized by FT‐IR, ¹H NMR, ¹³C NMR and ¹⁹F NMR in detail. The synthesized fluorinated surfactants have a high thermal stability on the basis of thermogravimetric analysis. Their surface properties were examined and the results show that FEOS‐1 and FEOS‐3 surfactants can reduce the surface tension of water to 25.55 mN m^?1 at 10.25 mmol L^?1 and 21.63 mN m^?1 at 8.33 mmol L^?1, respectively; meanwhile, the introduction of oxyethylene groups enhances the hydrophilicity and micellar forming ability and the longer oxyethylene chains the better surface properties. The Krafft points (K_p) of FEOS‐1 and FEOS‐3 were both below 0 °C, which was lower than perfluoro‐n‐heptanesulfonic acid sodium salt (n‐C₇F₁₅SO₃Na, K_p = 56.5 °C) at a similar length of fluorocarbon chains. Comparison studies on two surfactants above and the conventional fluorocarbon surfactants, perfluorooctanoate of ammonium (PFOA) show that the surfactants have comparable properties to PFOA, thus offering an environmentally friendly synthesizing alternatives to PFOA.     

Morphology controlling of micrometer-sized mesoporous silica spheres assisted by polymers of polyethylene glycol and methyl cellulose

Based on the PEG (polyethylene glycol)’s function of bridging flocculation and the MC (methyl cellulose)’s function of formation of liquid crystal in aqueous solution, the morphology of micrometer-sized mesoporous silica spheres with good dispersivity were synthesized by adding the mixture of PEG and MC into the aqueous solution containing F127 and TEOS. It was found that only when PEG was added, the micrometer sized spheres could be synthesized, the spheres possess meso-pores from 2.5 nm to 3.0 nm, and the specific surface area was from 744 m²/g to 861 m²/g by changing the amount of PEG, but the dispersibility of microspheres needs to be improved. Only when MC was added, the dispersibility of resultant spheres was good, but the out surface of spheres was not smooth. Then, when suitable amount of PEG and MC were simultaneously added, the spheres with good dispersibility and smooth out surface were obtained.     

Solvothermal synthesis of CdS nanowires templated by polyethylene glycol

CdS nanowires were solvothermally synthesized from Cd(NO₃)₂ and S powder using ethylenediamine as a solvent and polyethylene glycol (PEG) as a template. Hexagonal CdS with P6₃mc space group was detected using XRD and SAED, results which are in good accordance with those obtained by the simulation. SEM, TEM and HRTEM revealed the gradual development of nanowires in the [0 0 1] direction with a number of atoms aligning in a crystal lattice. Raman spectra of different products showed the fundamental and overtone modes at the same wavenumbers of 300 and 601 cm⁻¹, respectively. Their relative intensities at different molecular weight PEG were influenced by the anisotropic geometry of the products. Their photoluminescence peaks were detected at the same wavelengths of 518 nm. A formation mechanism for CdS nanowires was also proposed to relate to the experimental results.     

Direct UV-written highly fluorinated aromatic-aliphatic copolyethers for optical waveguides

A bisphenol monomer (4-methoxy) phenylhydroquinone (Me-HQ) was prepared and further polymerized with 2,2,3,3,4,4,5,5,6,6,7,7-dodeca-fluoro-1,8-octanediol (12F-diol) and decafluorobiphenyl (DFBP) to obtain highly fluorinated aromatic-aliphatic copolyethers containing methoxy groups. After demethylation and the reaction with epoxy chloropropane, a series of novel highly fluorinated aromatic-aliphatic copolyethers bearing epoxy groups (FA-APE EP) at different feed ratios of (Me-HQ)/(12F-diol) were obtained. The chemical structures of all the copolymers were analyzed by ¹H NMR, ¹³C NMR and ¹⁹F NMR spectra. A series of highly fluorinated photoresists were prepared by composing of fluorinated copolyethers, diphenyliodonium salt as a photoacid generator (PAG) and solvent. After UV-curing, the cross-linked films exhibited excellent chemical resistance and high thermal stability (T_d ranged from 230 to 278 °C). The refractive indices of the films could be controlled between 1.5127 and 1.4749 at 1550 nm by varying the feed ratio of comonomers. A clear negative pattern was obtained through direct UV exposure and chemical development. For waveguides without upper cladding, the propagation loss of the channel waveguides was measured to be 0.18 dB/cm at 1550 nm.     

一种非离子氟碳表面活性剂的合成及表征

以聚乙二醇、全氟丁酸为主要原料,采用直接酯化的方法,合成了一系列聚乙二醇系非离子型氟碳表面活性剂——聚乙二醇全氟丁酸酯(以单酯为主,且含有少量双酯),且对其红外光谱、表面张力、临界胶束浓度、浊点进行了测试。结果表明,该类氟碳表面活性剂具有很高的表面活性,同时,随PEG链段长度的变化,其表面张力、CMC值、浊点都发生规律性的变化。     

Synthesis of side group liquid crystal-coil triblock copolymers with cyanobiphenyl moieties and PEG as coil segments by atom-transfer radical polymerization and their thermotropic phase behavior

Summary A series of side group liquid crystal-coil(SGLC-coil) triblock copolymers with narrow polydispersity was synthesized by atom transfer radical polymerization (ATRP), which was designed to have LC conformation of poly(11-(4′-cyanophenyl-4″-phenoxy)undecyl methacrylate) and coil-conformation of polyethylene glycol (PEG) (Mn=6000) segment. The SGLC block was prepared with a rang of molecular weights from 3.5×10³ to 1.4×10⁴. The macro-initiator PEG6000-Br was synthesized with PEG and 2-Bromo-2-methylpropionyl bromide by reaction of acid bromide. Their characterization was investigated using proton nuclear magnetic resonance (¹H NMR), Fourier Transform Infrared (FT-IR) spectra, gel permeation chromatograph (GPC), differential scanning calorimetry (DSC) and polarized optical microscope (POM). All the block polymers exhibited a smectic A mesophase. The phase transition temperatures of the smectic to isotropic (T_S-T_I) phase increased and the crystallizability of PEG depressed with increasing of the molecular weight of the LC block. Received: 12 March 2002/Revised version: 25 April 2002/ Accepted: 30 April 2002     

Synthesis and characterization of low-refractive-index fluorinated silsesquioxane-based hybrids

Novel low-refractive-index silsesquioxane-based hybrids were synthesized via hydrolytic condensation of fluorinated triethoxysilane precursors, which were prepared by reacting 3-aminopropyl triethoxysilane with acrylates containing fluoroalkyl groups, 1H,1H,5H-octafluoropentyl acrylate (OFPA) and 2,2,2-trifluoroethyl acrylate (TFEA). The hydrolytic condensations proceeded as a homogeneous system in acetone in the presence of aqueous HF solution (3.2%) at 30 °C. The products were soluble in a variety of organic solvents, including CHCl₃, THF, and acetone, but were insoluble in hexane and water. The structures of the products were confirmed by ¹H NMR, ¹³C NMR, ¹⁹F NMR, and FT-IR spectroscopy. The low polydispersities and reasonable molecular weights of the resulting fluorinated silsesquioxanes (M_n = 5800, M_w/M_n = 1.01; and M_n = 4700, M_w/M_n = 1.04 for the OFPA- and TFEA-based products, respectively) were confirmed by size-exclusion chromatography. Scanning force microscope (SFM) measurements indicated the formation of spherical hybrids having relatively narrow size distributions (average particle diameter < 3.0 nm) without aggregation. The sizes of the hybrids were also confirmed by X-ray diffraction (XRD). The refractive indexes of the TFEA- and OFPA-based silsesquioxane hybrids were 1.43 and 1.40, respectively. These results indicate the formation of novel fluorinated silsesquioxane-based hybrids having good solubility, narrow size distribution, and a low refractive index. Co-condensation of the TFEA- and OFPA-based triethoxysilane precursors affords a series of fluorinated hybrids whose refractive index and various other properties can be manipulated by varying the composition of the feed.     

Hyperbranched homo and thermoresponsive graft copolymers by using ATRP‐macromonomer initiators

Macromonomer initiators behave as macro cross‐linkers, macro initiators, and macromonomers to obtain branched and cross‐linked block/graft copolymers. A series of new macromonomer initiators for atom transfer radical polymerization (MIM‐ATRP) based on polyethylene glycol (M_n = 495D, 2203D, and 4203D) (PEG) were synthesized by the reaction of the hydroxyl end of mono‐methacryloyl polyethylene glycol with 2‐bromo propanoyl chloride, leading to methacryloyl polyethylene glycol 2‐bromo propanoyl ester. Poly (ethylene glycol) functionalized with methacrylate at one end was reacted with 2‐bromopropionyl chloride to form a macromonomeric initiator for ATRP. ATRP was found to be a more controllable polymerization method than conventional free radical polymerization in view of fewer cross‐linked polymers and highly branched polymers produced from macromonomer initiators as well. In another scenario, ATRP of N‐isopropylacrylamide (NIPAM) was initiated by MIM‐ATRP to obtain PEG‐b‐PNIPAM branched block/graft copolymers. Thermal analysis, FTIR, ¹H NMR, TEM, and SEM techniques were used in the characterization of the products. They had a thermo‐responsive character and exhibited volume phase transition at ～ 36°C. A plasticizer effect of PEG in graft copolymers was also observed, indicating a lower glass transition temperature than that of pure PNIPAM. Homo and copolymerization kinetics were also evaluated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Blocked polyisocyanates containing fluorine atoms as crosslinking agents for polyurethane powder coatings

Using alicyclic diisocyanates (HDI, TMDI, IPDI, H₁₂MDI), aliphatic unfluorinated and fluorinated alcohols, dibutyltin dilaurate as well as triethylamine as catalysts, blocked polyisocyanate crosslinkers for powder lacquers were synthesized. The chemical structure of these compounds was characterized by means of IR, ¹H‐NMR, ¹³C‐NMR, and ¹⁹F‐NMR spectroscopy. Their molecular weight distribution parameters were determined by gel permeation chromatography. These blocked polyisocyanates were used for the production of powder lacquer compositions and coatings. The three‐dimensional surface topography and surface chemical structure of the resulting powder lacquers were investigated by means of confocal microscope and ATR FT‐IR. The values of surface roughness parameters were calculated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis of hydroxyl-capped comb-like poly(ethylene glycol) to develop shell cross-linkable micelles

A novel hydroxyl-capped comb-like poly[poly(ethylene glycol) methacrylate] (PPEGMA) was prepared via atom transfer radical polymerization (ATRP) of α-methylacryloyl-ω-hydroxyl-poly(ethylene glycol) at ambient temperature. The polymerization kinetics of the block copolymer was studied by gel permeation chromatography (GPC) and ¹H NMR. It is of interest to find the well-defined comb-like PEG can associate into micelles, which have hydrophilic PEG shell end-capped by hydroxyl groups. The hydroxyl in the shell were further cross-linked by divinyl sulfone (DVS), which could couple with two capped-end hydroxyl groups. The XPS, TEM, AFM and laser scattering particle size distribution analyzer results revealed that reactive micelles could be cross-linked by DVS. The reactive, cross-linkable micelles with PEG shell may have great potential as new drug carrier and nanoreactor, etc.     

Synthesis of PEG‐functionalized poly(diphenylacetylene)s and their gas permeation properties

The polymerizations of 1‐(3‐methylphenyl)‐2‐(4‐trimethylsilyl)phenylacetylene ( 1a ) and 1‐(4‐methylphenyl)‐2‐(4‐trimethylsilyl)phenylacetylene ( 1b ) were carried out with TaCl₅‐n‐Bu₄Sn to give relatively high‐molecular‐weight polymers ( 2a and 2b ) (M_n > 5 × 10⁵). The obtained polymers were brominated by using benzoyl peroxide and N‐bromosuccinimide first, followed by substitution reaction of three types of polyethylene glycol. When diethylene glycol was used as a reagent on substitution reaction of meta‐substituted polymer, PEG‐functionalized poly(diphenylacetylene) with the highest content of oxyethylene unit [ 4a(2) ] was obtained, and the degree of substitution was 0.60. The degrees of substitution decreased to 0.15 and 0.08 when the polyethylene glycols with higher molecular weights were used. PEG‐substitution reaction to the para‐substituted polymers was difficult to proceed, and hence the degree of substitution was 0.18 even when diethylene glycol was used. The CO₂/N₂ separation factor of PEG‐functionalized polymer [ 4a(2) ] was as large as 28.8, although that of 2a was 7.41. The other PEG‐functionalized polymers also exhibited high CO₂ permselectivity, and their CO₂/N₂ separation factors were over 20. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Size-controlled synthesis of mesoporous silica nanoparticles using rice husk by microwave-assisted sol–gel method

Mesoporous silica nanoparticles with distinct characteristics like particle size, tunable pores, and high surface area have received much interest for environmental remediation, energy conversion, and biological applications. In this work, we synthesized spherical silica nanoparticles with tunable particle size and mesoporous properties using a low-cost silica source (rice husk) and polyethylene glycol (PEG) via microwave-assisted sol–gel synthesis. The formation of an amorphous silica structure was found using XRD and FTIR analysis. FESEM analysis showed that altering the PEG concentration from .01 to .005 M produced spherical silica nanoparticles with 100–500 nm in size. Nitrogen adsorption–desorption demonstrated that silica nanoparticles obtained with .005, .007, and .01 M of PEG had unique pore sizes and distributions, with specific surface areas of 51.475, 62.367, and 84.251 m²/g, respectively. These results might be due to PEG molecules’ capping effect, which acts as a soft template to regulate particle size, pore size, and dispersion by interacting with sodium silicate precursor. Hence, this approach can be a facile and cost-effective method to prepare mesoporous silica nanoparticles with controllable nanoscale characteristics for suitable applications.     

Synthesis, characterization and properties of chitosan modified with poly(ethylene glycol)-polydimethylsiloxane amphiphilic block copolymers

Synthesis of poly(ethylene glycol)-polydimethylsiloxane amphiphilic block copolymers is discussed herein. Siloxane prepolymer was first prepared via acid-catalyzed ring-opening polymerization of octamethylcyclotetrasiloxane (D₄) to form polydimethylsiloxane (PDMS) prepolymers. It was subsequently functionalized with hydroxy functional groups at both terminals. The hydroxy-terminated PDMS can readily react with acid-terminated poly(ethylene glycol) (PEG diacid) to give PEG-PDMS block copolymers without using any solvent. The PEG diacid was prepared from hydroxy-terminated PEG through the ring-opening reaction of succinic anhydride. Their chemical structures and molecular weights were characterized using ¹H NMR, FTIR and GPC, and thermal properties were determined by DSC. The PEG-PDMS copolymer was incorporated into chitosan in order that PDMS provided surface modification and PEG provided good water swelling properties to chitosan. Critical surface energy and swelling behavior of the modified chitosan as a function of the copolymer compositions and contents were investigated.     

Folic acid-modified iridium(III) coordination polymeric nanoparticles facilitating intracellular release of a phosphorescent residue capable of nuclear entry

Functional polymeric nanoparticles with folic acid end-capped poly(ethylene glycol) (PEG) as the shell and an iridium(III) complex coupled with poly(4-vinylpyridine) (P4VP)/[Ir(pq)₂] (pq = 2-phenylquinoline) as the core have been prepared through complexation of the pyridine moiety with [Ir(pq)₂]₂⁺ followed by dialysis against water. The nanoparticles with folic acid on the surface are capable of entering HeLa cells. It is significant that, after cellular internalization, the intracellular compound histidine can trigger release of the [Ir(pq)₂]⁺ residue into the nucleus from the nanoparticles. This provides a new pathway for triggering the release of drugs from their carriers.     

Preparation and Properties of Hyperbranched Polyurethanes via Oligomeric A<Subscript>2</Subscript>+bB<Subscript>2</Subscript> Approach

Hyperbranched polyurethanes (HPUs) were synthesized from isocyanate end-capped poly(1,4-butylene adipate glycol) and diethanolamine via oligomeric A₂ + bB₂ approach. The structures of the resulting polymers were characterized by FT-IR, ¹³C NMR. The degree of branching (DB) was calculated according to the ¹³C NMR spectra. The properties of HPUs were investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), adhesion strength tests. It was found that the thermal stability of the HPU decreased with the increase of hard segment content. The HPU could be used as hot melt adhesive, and the maximum lap shear strength was up to 6.84 MPa.     

Structural/Optical Properties and CO Oxidation Activities of SnO2 Nanostructures

Tetragonal SnO₂ nanostructures with different sizes, band gaps, and defects were synthesized by varying the amounts of ammonia and polyethylene glycol (PEG) used during production and their structural and optical properties were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD) crystallography, BET surface area analysis, thermogravimetric analysis, Raman spectroscopy, UV–visible absorption spectroscopy, photoluminescence imaging, and X‐ray photoelectron spectroscopy. In addition, the CO oxidation activity was examined by temperature‐programmed reduction and temperature‐programmed CO oxidation measurements. SEM and XRD analysis revealed that the particle size decreased with increasing PEG, but increased with increasing ammonia. Additionally, the band gaps decreased with increasing ammonia, but not with increasing PEG. Tetragonal SnO formed when larger amounts of ammonia were used, and this was converted to SnO₂ upon annealing at temperatures up to 700°C. The SnO₂ showed a unique strong green emission at 560 nm, which was attributed to a new oxygen deficiency. In addition, a sharp (328 nm) and two broad (390 and 460 nm) photoluminescence peaks corresponding to gap emission and the oxygen vacancies, respectively, were observed. The difference in CO oxidation activity with SnO₂ was attributed to varying sizes and defects formed in response to preparation under different reaction conditions.     

Experimental investigation of operating conditions for preparation of PVA–PEG blend membranes using supercritical CO2

Poly(vinyl alcohol)–polyethylene glycol, PVA–PEG, blended membrane were prepared using supercritical fluid assisted phase-inversion method, in which scCO₂ was used as the anti-solvent. Poly(vinyl alcohol) was utilized as the main polymer, polyethylene glycol as the additive, and dimethyl sulfoxide (DMSO) as the solvent of these polymers. Taguchi method was used to investigate the effect of some operating parameters on the morphology of the membranes. The L16 orthogonal array was selected under the following conditions: pressure (100, 135, 165 and 200 bar), temperature (40, 45, 50 and 55 °C) and PEG weight percent (0, 0.33, 0.66, and 1%). Total polymer concentration of solutions in all experiment was constant at 10% (w/w). The morphology of the obtained porous membranes was characterized by scanning electron microscopy. Through changing the conditions in each experiment, the average pore diameter changed between 3.75 and 12.2 μm. Results from analysis of variance (ANOVA) indicate that PEG concentration was the most significant factor on the average pore size of prepared membranes by 78.7%. This is the first work announcing preparation of PVA–PEG membrane using supercritical CO₂.     

Nanoparticle formulation of poly(?-caprolactone-co-lactide)-d-α-tocopheryl polyethylene glycol 1000 succinate random copolymer for cervical cancer treatment

Cervical cancer remains a critical problem that is second only to breast cancer affecting women worldwide. The objective of this study was to develop formulation of docetaxel-loaded biodegradable poly(?-caprolactone-co-lactide)-d-α-tocopheryl polyethylene glycol 1000 succinate (PCL-PLA-TPGS) nanoparticles for cervical cancer chemotherapy. A novel random copolymer, PCL-PLA-TPGS, was synthesized from ?-caprolactone, lactide and d-a-tocopheryl polyethylene glycol 1000 succinate (TPGS) by ring-opening polymerization. The obtained polymers were characterized by ¹H NMR, FTIR, GPC and TGA. The docetaxel-loaded PCL-PLA-TPGS nanoparticles were prepared by a modified solvent extraction/evaporation technique and characterized in terms of size and size distribution, morphology, surface charge and physical state of encapsulated docetaxel. Cellular uptake and in vitro cytotoxicity of nanoparticle formulations were done in comparison with commercial formulation Taxotere^® to investigate the efficacy of PCL-PLA-TPGS nanoparticles. In vitro cellular uptakes of such nanoparticles were investigated with CLSM, demonstrating the coumarin 6-loaded PCL-PLA-TPGS nanoparticles could be internalized by Hela cells. In vitro cancer cell viability experiment showed that judged by IC₅₀, the PCL-PLA-TPGS nanoparticle formulation was found to be more effective in cell number reduction than the Taxotere^® after 48 h (p < 0.05), 72 h (p < 0.05) treatment. In conclusion, the PCL-PLA-TPGS copolymer could be acted as a novel and promising biologically active polymeric matrix material for nanoparticle formulation in cervical cancer treatment.