scholarly journals Synthesis and Properties of Side-Chain Functionalized Polytetrahydrofuran Derivatives via the Blue-Light Photocatalytic Thiol-Ene Reaction

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 583
Author(s):  
Xiuzhong Zhu ◽  
Ting Bai ◽  
Zichao Wang ◽  
Jie Liu ◽  
Xin Min ◽  
...  
Keyword(s):  
Blue Light ◽  
Self Assembly ◽  
Potassium Hydroxide ◽  
High Efficiency ◽  
Click Reaction ◽  
Size Exclusion ◽  
Side Chain ◽  
Condensation Polymerization ◽  
Ene Reaction ◽  
Exclusion Chromatography

A series of side-chain functionalized polytetrahydrofuran (PTHF) derivatives were synthesized via the blue-light photocatalytic thiol-ene “click” reaction. Firstly, unsaturated polytetrahydrofuran (UPTHF) as a new unsaturated polyether was synthesized via condensation polymerization of cis-2-butene-1,4-diol and trans-1,4-dibromo-2-butene using potassium hydroxide (KOH) as a catalyst. Then, double bonds in the backbone of UPTHF were modified into different pendant functionality side groups by blue-light photocatalytic thiol-ene “click” reaction using Ru(bpy)3Cl2 as a photoredox catalyst, obtaining different side-chain functionalized PTHF derivatives. The structure and the morphology of the side-chain functionalized PTHF derivatives was characterized via Fourier-transform infrared spectra (FTIR), nuclear magnetic resonance (NMR), size exclusion chromatography/multi-angle laser light scattering (SEC/MALLS), and differential scanning calorimeter (DSC). The results showed that the blue-light photocatalytic thiol-ene reaction exhibited high efficiency, and all the unsaturated bonds were modified. Different branch units bestowed different performance of PTHF derivatives; we systematically investigated the thermal properties, pH-triggered and temperature-triggered, self-assembly behaviors of different PTHF derivatives.

Combined Main- and Side-Chain Azobenzene Polyesters: A Potential For Photoinduced Nonlinear Waveguides

1999 ◽  
Vol 561 ◽  
Author(s):  
F. Sahlén ◽  
T. Geisler ◽  
S. Hvilsted ◽  
N. C. R. Holme ◽  
P. S. Ramanujam ◽  
...  
Keyword(s):  
Refractive Index ◽  
Third Harmonic Generation ◽  
Size Exclusion ◽  
Side Chain ◽  
Visible Spectroscopy ◽  
Scanning Calorimetry ◽  
Nonlinear Waveguides ◽  
Third Harmonic ◽  
Exclusion Chromatography ◽  
Uv Visible

ABSTRACTNew combined main- and side-chain azobenzene polyesters, which exhibit an intensity dependent refractive index, have been prepared in order to optically fabricate nonlinear waveguides. Novel sulfone azobenzenes, a diester, (4-[[5-(ethoxycarbonyl)pentyl]sulfonyl]-4'-[[5-(ethoxycarbonyl)pentyl]methylamino] azobenzene, and a diol, 4-[[(8-hydroxy-7-methylhydroxy)-octyl]sulfonyl]-4'-N, N-dimethylamino azobenzene, have been used to prepare new polyesters by transesterification in the molten state. The polyesters have been characterized by UV-visible spectroscopy, differential scanning calorimetry (DSC), size exclusion chromatography (SEC), third harmonic generation (THG) and optical anisotropy measurements. The molar masses of the polyesters were in the range of 5000-10000 g mol−1, which was sufficient in order to spin coat thin films. From THG measurements the polymers are shown to possess an offresonance electronic X(3) of the order 10−12 esu corresponding to a nonlinear refractive index of 2.3×10−14 cm2/W.

Monitoring the chemical heterogeneity of metallocenecatalysed copolymers of ethylene and higher 1-olefins using CRYSTAF and SEC-FTIR

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Sven M. Graef ◽  
Robert Brüll ◽  
Harald Pasch ◽  
Udo M. Wahner
Keyword(s):  
Differential Scanning Calorimetry ◽  
Size Exclusion Chromatography ◽  
Catalyst System ◽  
Size Exclusion ◽  
Side Chain ◽  
Chemical Heterogeneity ◽  
Scanning Calorimetry ◽  
Crystallisation Temperature ◽  
Exclusion Chromatography

Abstract Copolymers of ethylene with 1-decene, 1-tetradecene and 1-octadecene were prepared using the catalyst system racEt[Ind]2ZrCl2/MAO and were analysed with regard to chemical heterogeneity using crystallisation analysis fractionation (CRYSTAF), differential scanning calorimetry (DSC) and size exclusion chromatography coupled to FTIR (SEC-FTIR). The melting and crystallisation temperatures from DSC decrease linearly with increasing amount of comonomer, independently of the nature thereof. The decrease in crystallisation temperature from CRYSTAF of copolymers with higher 1-olefin content indicates a small dependence on the length of the side chain. The chemical heterogeneity of the copolymers as analysed by DSC and CRYSTAF broadens with increasing comonomer concentration.

scholarly journals A New Hyaluronan Modified with β-Cyclodextrin on Hydroxymethyl Groups Forms a Dynamic Supramolecular Network

Molecules ◽  
2019 ◽  
Vol 24 (21) ◽  
pp. 3849
Author(s):  
Jelica Kovačević ◽  
Zdeňka Prucková ◽  
Tomáš Pospíšil ◽  
Věra Kašpárková ◽  
Michal Rouchal ◽  
...  
Keyword(s):  
Click Reaction ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Supramolecular Network ◽  
Stimuli Responsive ◽  
Calorimetric Titration ◽  
Supramolecular Architectures ◽  
1H Nuclear Magnetic Resonance ◽  
Exclusion Chromatography ◽  
Chemical Stimuli

A new hyaluronan derivative modified with β-cyclodextrin units (CD-HA) was prepared via the click reaction between propargylated hyaluronan and monoazido-cyclodextrin (CD) to achieve a degree of substitution of 4%. The modified hyaluronan was characterized by 1H-nuclear magnetic resonance spectroscopy (NMR) and size exclusion chromatography. Subsequent 1H-NMR and isothermal calorimetric titration experiments revealed that the CD units on CD-HA can form virtual 1:1, 1:2, and 1:3 complexes with one-, two-, and three-site adamantane-based guests, respectively. These results imply that the CD-HA chains used the multitopic guests to form a supramolecular cross-linked network. The free CD-HA polymer was readily restored by the addition of a competing macrocycle, which entrapped the cross-linking guests. Thus, we demonstrated that the new CD-HA polymer is a promising component for the construction of chemical stimuli-responsive supramolecular architectures.

scholarly journals Production of Aromatic Compounds by Catalytic Depolymerization of Technical and Downstream Biorefinery Lignins

Biomolecules ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1338 ◽  
Author(s):  
Alfonso Cornejo ◽  
Fernando Bimbela ◽  
Rui Moreira ◽  
Karina Hablich ◽  
Íñigo García-Yoldi ◽  
...  
Keyword(s):  
Aromatic Compounds ◽  
Quantum Coherence ◽  
Base Catalysis ◽  
Industrial Wastes ◽  
Size Exclusion ◽  
Side Chain ◽  
Resonance Spectroscopy ◽  
Alkyl Side Chain ◽  
Alkyl Side Chains ◽  
Exclusion Chromatography

Lignocellulosic materials are promising alternatives to non-renewable fossil sources when producing aromatic compounds. Lignins from Populus salicaceae. Pinus radiata and Pinus pinaster from industrial wastes and biorefinery effluents were isolated and characterized. Lignin was depolymerized using homogenous (NaOH) and heterogeneous (Ni-, Cu- or Ni-Cu-hydrotalcites) base catalysis and catalytic hydrogenolysis using Ru/C. When homogeneous base catalyzed depolymerization (BCD) and Ru/C hydrogenolysis were combined on poplar lignin, the aromatics amount was ca. 11 wt.%. Monomer distributions changed depending on the feedstock and the reaction conditions. Aqueous NaOH produced cleavage of the alkyl side chain that was preserved when using modified hydrotalcite catalysts or Ru/C-catalyzed hydrogenolysis in ethanol. Depolymerization using hydrotalcite catalysts in ethanol produced monomers bearing carbonyl groups on the alkyl side chain. The analysis of the reaction mixtures was done by size exclusion chromatography (SEC) and diffusion ordered nuclear magnetic resonance spectroscopy (DOSY NMR). 31P NMR and heteronuclear single quantum coherence spectroscopy (HSQC) were also used in this study. The content in poly-(hydroxy)-aromatic ethers in the reaction mixtures decreased upon thermal treatments in ethanol. It was concluded that thermo-solvolysis is key in lignin depolymerization, and that the synergistic effect of Ni and Cu provided monomers with oxidized alkyl side chains.

scholarly journals Amphiphilic Polypeptides for VEGF siRNA Delivery into Retinal Epithelial Cells

Pharmaceutics ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 39 ◽  
Author(s):  
Olga Osipova ◽  
Vladimir Sharoyko ◽  
Natalia Zashikhina ◽  
Natalya Zakharova ◽  
Tatiana Tennikova ◽  
...  
Keyword(s):  
Drug Release ◽  
Self Assembly ◽  
Messenger Rna ◽  
Sirna Delivery ◽  
Aqueous Media ◽  
Size Exclusion ◽  
Nucleic Acid Delivery ◽  
Cationic Polymers ◽  
Polymer Carriers ◽  
Exclusion Chromatography

Polyethyleneimine, poly-L-lysine, chitosan and some others cationic polymers have been thoroughly studied as nucleic acid delivery systems in gene therapy. However, the drug release from these systems proceeds at a very low rate due to extremely high binding between a carrier and gene material. To reduce these interactions and to enhance drug release, we developed a set of amphiphilic polypeptides containing positively and negatively charged amino acids as well as a hydrophobic one. The copolymers obtained were characterized by size-exclusion chromatography, static light scattering, HPLC amino acid analysis and 1HNMR spectroscopy. All copolymers formed particles due to a self-assembly in aqueous media. Depending on polypeptide composition, the formation of particles with hydrodynamic diameters from 180 to 900 nm was observed. Stability of polymer particles, loading and release efficiency were carefully studied. Cellular uptake of the particles was efficient and their cytotoxicity was negligible. The application of polymer carriers, containing siRNA, to vascular endothelial growth factor (VEGF-A165) silencing of ARPE-19 cells was successful. The gene silencing was confirmed by suppression of both messenger RNA and protein expression.

scholarly journals Versatile Construction of Single-Tailed Giant Surfactants with Hydrophobic Poly(ε-caprolactone) Tail and Hydrophilic POSS Head

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 311 ◽  
Author(s):  
Qiangyu Qian ◽  
Jun Xu ◽  
Mingzu Zhang ◽  
Jinlin He ◽  
Peihong Ni
Keyword(s):  
Small Molecule ◽  
Self Assembly ◽  
High Efficiency ◽  
Click Reaction ◽  
Gel Permeation Chromatography ◽  
Hydroxyl Groups ◽  
Design And Synthesis ◽  
Synthetic Strategy ◽  
Head Surface ◽  
Different Diameters

Giant surfactants refer to a new kind of amphiphile by incorporating functional molecular nanoparticles with polymer tails. As a size-amplified counterpart of small-molecule surfactants, they serve to bridge the gap between small-molecule surfactants and amphiphilic block copolymers. This work reports the design and synthesis of single-tailed giant surfactants carrying a hydrophobic poly(ε-caprolactone) (PCL) as the tail and a hydrophilic cage-like polyhedral oligomeric silsesquioxane (POSS) nanoparticle as the head. The modular synthetic strategy features an efficient ‘‘growing-from’’ and ‘‘click-modification’’ approach. Starting from a monohydroxyl and heptavinyl substituted POSS (VPOSS-OH), a PCL chain with controlled molecular weight and narrow polydispersity was first grown by the ring-opening polymerization (ROP) of ε-CL under the catalysis of stannous octoate, leading to a PCL chain end-capped with heptavinyl substituted POSS (VPOSS-PCL). To endow the POSS head with adjustable polarity and functionality, three kinds of hydrophilic groups, including hydroxyl groups, carboxylic acids, and amine groups, were installed to the periphery of POSS molecule by a high-efficiency thiol-ene “click” reaction. The compounds were fully characterized by NMR, gel permeation chromatography (GPC), MALDI-TOF mass spectrometry, and TGA analysis. In addition, the preliminary self-assembly study of these giant surfactants was also investigated by TEM and dynamic laser light scattering (DLS), which indicated that they can form spherical nanoparticles with different diameters in aqueous solution. This work affords a straightforward and versatile way for synthesizing single-tailed giant surfactants with diverse head surface functionalities.

scholarly journals Influence of Monomer Ratios on Molecular Weight Properties and Dispersing Effectiveness in Polycarboxylate Superplasticizers

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1022 ◽  
Author(s):  
Huiqun Li ◽  
Yan Yao ◽  
Ziming Wang ◽  
Suping Cui ◽  
Yali Wang
Keyword(s):  
Molecular Weight ◽  
Polyethylene Glycol ◽  
Acrylic Acid ◽  
Reaction Rate ◽  
Main Chain ◽  
Size Exclusion ◽  
Side Chain ◽  
Time Interval ◽  
Exclusion Chromatography ◽  
Low Dosage

A series of polycarboxylate superplasticizer (PCE) polymers were synthesized from acrylic acid (AA) and isoprenyloxy polyethylene glycol ether (IPEG) at the mole ratios of 3.0, 4.2, 5.0 and 6.0. In this study, the molecular weight properties of PCE polymers were recorded by size exclusion chromatography with the time interval of 1 h. Mini slump test was used to detect the dispersing effectiveness of PCE polymer in cement paste. The results indicated that the reaction rate of monomers, conversion of 52IPEG macromonomer and molecular weight of PCE polymers increased with the general adding ratio of AA to IPEG macromonomers while the side chain density of PCE polymers decreased. PCE polymers possessed molecular weight around 30,000 g/mol with low side chain density, and long main chain length presented high initial dispersing effectiveness at the low dosage around 0.12%. The majority of effective PCE polymers were formed during the adding period of acrylic acid in the first 3 h.

scholarly journals Self-assembly of SNARE fusion proteins into star-shaped oligomers

2005 ◽  
Vol 388 (1) ◽  
pp. 75-79 ◽  
Author(s):  
Colin RICKMAN ◽  
Kuang HU ◽  
Joe CARROLL ◽  
Bazbek DAVLETOV
Keyword(s):  
Self Assembly ◽  
Quaternary Structure ◽  
Intrinsic Property ◽  
Full Length ◽  
Fusion Process ◽  
Size Exclusion ◽  
Negative Stain ◽  
Protein Receptors ◽  
Exclusion Chromatography

Three evolutionarily conserved proteins known as SNAREs (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptors) mediate exocytosis from single cell eukaryotes to neurons. Among neuronal SNAREs, syntaxin and SNAP-25 (synaptosome-associated protein of 25 kDa) reside on the plasma membrane, whereas synaptobrevin resides on synaptic vesicles prior to fusion. The SNARE motifs of the three proteins form a helical bundle which probably drives membrane fusion. Since studies in vivo suggested an importance for multiple SNARE complexes in the fusion process, and models appeared in the literature with large numbers of SNARE bundles executing the fusion process, we analysed the quaternary structure of the full-length native SNARE complexes in detail. By employing a preparative immunoaffinity procedure we isolated all of the SNARE complexes from brain, and have shown by size-exclusion chromatography and negative stain electron microscopy that they exist as approx. 30 nm particles containing, most frequently, 3 or 4 bundles emanating from their centre. Using highly purified, individual, full-length SNAREs we demonstrated that the oligomerization of SNAREs into star-shaped particles with 3 to 4 bundles is an intrinsic property of these proteins and is not dependent on other proteins, as previously hypothesized. The average number of the SNARE bundles in the isolated fusion particles corresponds well with the co-operativity observed in calcium-triggered neuronal exocytosis.

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