New Metal-Chalcogen Compounds with Polymeric Structures

1991 ◽  
pp. 263-276 ◽  
Author(s):  
Y. Park ◽  
J.-H. Liao ◽  
K.-W. Kim ◽  
M. G. Kanatzidis
Keyword(s):  
Polymeric Structures

Axially Chiral Bis(α-amino Acid)s and Their Deamino Analogues. Synthesis and Configurational Assignment

1998 ◽  
Vol 63 (2) ◽  
pp. 211-221 ◽  
Author(s):  
Miloš Tichý ◽  
Luděk Ridvan ◽  
Miloš Buděšínský ◽  
Jiří Závada ◽  
Jaroslav Podlaha ◽  
...  
Keyword(s):  
Amino Acid ◽  
Nmr Spectra ◽  
Building Blocks ◽  
X Ray Diffraction ◽  
Amino Groups ◽  
X Ray ◽  
Configurational Assignment ◽  
Symmetry Properties ◽  
Axially Chiral ◽  
Polymeric Structures

The axially chiral bis(α-amino acid)s cis-2 and trans-2 as possible building blocks for polymeric structures of novel type of helicity were prepared. Their configuration has been determined by NMR spectroscopy and, in the case of the trans-isomer, confirmed by single-crystal X-ray diffraction. Analogous pair of stereoisomeric diacids cis-3 and trans-3, devoid of the amino groups, was also prepared and their configuration assigned. The observed differences in the NMR spectra of cis- and trans-isomers of 2 and 3 are discussed from the viewpoint of their different symmetry properties.

scholarly journals Molar mass determination of lignins and characterization of their polymeric structures by multi-detector gel permeation chromatography

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Evamaria C. Gaugler ◽  
Wolfgang Radke ◽  
Andrew P. Vogt ◽  
Dawn A. Smith
Keyword(s):  
Molar Mass ◽  
Lithium Bromide ◽  
Gel Permeation Chromatography ◽  
Mass Determination ◽  
Organosolv Lignin ◽  
Gel Permeation ◽  
Softwood Kraft Lignin ◽  
Polymeric Structures

AbstractMolar masses, Mark-Houwink-Sakurada (MHS) exponents, and refractive index increments (dn/dc) for three lignins were determined without derivatization by multi-detector gel permeation chromatography (GPC) in dimethylformamide (DMF) with 0.05 M lithium bromide (LiBr). The lack of effectiveness of fluorescence filters on molar mass determination by GPC-multi-angle laser light scattering (MALS) was confirmed for softwood kraft lignin (Indulin AT) and revealed for mixed hardwood organosolv lignin (Alcell) as well as soda straw/grass lignin (Protobind 1000). GPC with viscometry detection confirmed that these lignins were present as compact molecules. The MHS exponent α for Indulin AT and Alcell was in the order of 0.1. Additionally, the intrinsic viscosity of Protobind 1000 for a given molar mass was much lower than that of either Alcell or Indulin AT. This is the first report of dn/dc values for these three lignins in DMF with 0.05 M LiBr.

scholarly journals Bio-Inspired Polymeric Structures with Special Wettability and Their Applications: An Overview

Polymers ◽  
2017 ◽  
Vol 9 (12) ◽  
pp. 725 ◽  
Author(s):  
Zihe Pan ◽  
Fangqin Cheng ◽  
Boxin Zhao
Keyword(s):  
Polymeric Structures

Effect of polymer matrix on photo-stability of photo-luminescent dyes in multi-layer polymeric structures

2001 ◽  
Vol 73 (3) ◽  
pp. 403-410 ◽  
Author(s):  
I. Baumberg ◽  
O. Berezin ◽  
A. Drabkin ◽  
B. Gorelik ◽  
L. Kogan ◽  
...  
Keyword(s):  
Polymer Matrix ◽  
Photo Luminescent ◽  
Photo Stability ◽  
Polymeric Structures

Amperometric Glucose Biosensors Based on Composite Polymeric Structures to Prevent Interferences

2000 ◽  
Vol 33 (9) ◽  
pp. 1733-1753 ◽  
Author(s):  
Pascal Mailley ◽  
Serge Cosnier ◽  
Liliance Coche-Guérente
Keyword(s):  
Glucose Biosensors ◽  
Amperometric Glucose Biosensors ◽  
Polymeric Structures

Toxicity And Surface Modification Of Dendrimers: A Critical Review

2021 ◽  
Vol 18 ◽  
Author(s):  
Rohini Kharwade ◽  
Payal Badole ◽  
Nilesh Mahajan ◽  
Sachin More
Keyword(s):  
Surface Modification ◽  
Positive Charge ◽  
Haematological Toxicity ◽  
Three Dimensional ◽  
Different Types ◽  
Hemolytic Toxicity ◽  
High Degree ◽  
Core Functionality ◽  
Polymeric Structures

: As compared to other nano polymers, dendrimers have novel three dimensional, synthetic hyperbranched, nano-polymeric structures. The characteristic of these supramolecular dendritic structures has a high degree of significant surface as well as core functionality in the transportation of drugs for targeted therapy, specifically in host-guest response, gene transfer therapy and imaging of biological systems. However, there are conflicting shreds of evidence regarding biological safety and dendrimers toxicity due to their positive charge at the surface. It includes cytotoxicity, hemolytic toxicity, haematological toxicity, immunogenicity and in vivo toxicity. Therefore to resolve these problems surface modification of the dendrimer group is one of the methods. From that point, this review involves different strategies which reduce the toxicity and improve the biocompatibility of different types of dendrimers. From that viewpoint, we broaden the structural and safe characteristics of the dendrimers in the biomedical and pharmaceutical fields.

Fabrication of porous polymeric structures using a simple sonication technique for tissue engineering

2017 ◽  
Vol 37 (9) ◽  
pp. 943-951 ◽  
Author(s):  
Alan Saúl Álvarez-Suarez ◽  
Eduardo Alberto López-Maldonado ◽  
Olivia A. Graeve ◽  
Fabián Martinez-Pallares ◽  
Luis Enrique Gómez-Pineda ◽  
...  
Keyword(s):  
Chemical Structure ◽  
Poly Vinyl Alcohol ◽  
Porous Structures ◽  
Average Pore ◽  
Ultrasonic Probe ◽  
Polymeric Scaffolds ◽  
Before And After ◽  
Water Absorption Test ◽  
Sonication Technique ◽  
Polymeric Structures

AbstractPorous polymeric scaffolds have been applied successfully in the biomedical field. This work explores the use of an ultrasonic probe to generate cavitation in a polymeric solution, thus producing pores in the polymeric scaffolds. Porous polymeric structures with average pore sizes ranging from 5 to 63 μm and porosity of 6–44% were fabricated by a process consisting of sonication, flash freezing, and lyophilization of poly(lactic-co-glycolic acid) (PLGA), gelatin (GEL), chitosan (CS) and poly(vinyl alcohol) (PVAL) solutions. Pore structure was characterized by scanning electron microscopy (SEM) and image analysis software. The infrared spectra were analyzed before and after the fabrication process to observe any change in the chemical structure of the polymers. A water absorption test indicated the susceptibility of the samples to retain water in their structure. TGA results showed that GEL experienced degradation at 225°C, CS had a decomposition peak at 280°C, the thermal decomposition of PLGA occurred at 375°C, and PVAL showed two degradation regions. The DSC analysis showed that the glass transition temperature (Tg) of GEL, CS, PLGA and PVAL occurred at 70°C, 80°C, 60°C and 70°C, respectively. The fabricated porous structures demonstrated similar physical characteristics to those found in bone and cartilage.

Synthesis and Vibrational and Mass Spectra of Ph3SnO2PMe2, Ph3SnO2PMePh and Ph3SnO2PPh2

1994 ◽  
Vol 49 (10) ◽  
pp. 1319-1323 ◽  
Author(s):  
Abdel-Fattah Shihada
Keyword(s):  
Raman Spectra ◽  
Mass Spectra ◽  
Ir And Raman Spectra ◽  
Phenyl Radicals ◽  
Ir And Raman ◽  
Fragmentation Processes ◽  
Polymeric Structures

AbstractThe reactions of (Ph3Sn)2O with PhMePOCl and with Ph2POCl lead to Ph3SnO2PMePh and Ph(SnO2PPh2, respectively. Ph3SnO2PMe2 has been prepared from the reaction of (Ph3Sn)2O and Me2PO2H in toluene. The IR and Raman spectra of Ph3SnO2PMe2, Ph3(SnO2PMePh and Ph3SnO2PPh2 are found to be consistent with polymeric structures with pentacoordinated tin atoms. The EI mass spectra indicate that the principal fragmentation processes of Ph3SnO2PRR′ (RR′ = Me2, MePh, Ph2) appear to occur by loss of phenyl radicals from tin and by elimination of the entire diorganophosphinate group.

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