Synthesis and properties of segmented main-chain liquid-crystalline polyurethanes with a high aspect ratio mesogenic diol as a chain extender

2002 ◽  
Vol 40 (10) ◽  
pp. 1527-1538 ◽  
Author(s):  
T. Padmavathy ◽  
K. S. V. Srinivasan
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Liquid Crystalline ◽  
Main Chain ◽  
Chain Extender ◽  
A Chain

Structure–properties relationship of the polyurethanes that contain Schiff base in the main chain

2020 ◽  
Vol 32 (7) ◽  
pp. 784-792
Author(s):  
Stefan Oprea ◽  
Violeta Otilia Potolinca ◽  
Veronica Oprea ◽  
Livia Ingrid Diaconu
Keyword(s):  
Schiff Base ◽  
Main Chain ◽  
Raw Materials ◽  
Mechanical Analysis ◽  
Thermomechanical Properties ◽  
Chain Extender ◽  
Cross Linking ◽  
Practical Applications ◽  
Molar Ratios ◽  
A Chain

This article studies the diversification of useful properties of polyurethane (PU) structures by the inclusion of new components. PUs containing a Schiff base in the main chain were synthesized by using N, N′-bis(salicylidene)-1,3-propanediamine as a chain extender. Novel Schiff base PUs were synthesized via a two-step polymerization starting from a Schiff base derivative diol chain extender with different molar ratios or by cross-linking with various natural raw materials. The sought after structures was confirmed by Fourier transform infrared spectra that showed the disappearance of the signals of both the hydroxyl and isocyanate groups. The thermal properties of these PUs were investigated by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The initial degradation temperatures of the obtained PUs were found to be in the range of 300–350°C. Based on the results from DMA, the rigid structure of the Schiff base from the backbone of the PUs presented a higher storage modulus, results which may be connected to the physical cross-linking process of the macromolecules. Their optical properties were determined by fluorescence spectroscopy. The incorporation of Schiff base structures into the main PU chain generates new PU structures with improved thermomechanical properties, which includes possible bioactive Schiff base moieties, widening the range of practical applications for such polymers.

Metal-Containing Polyurethanes: An Overview

2010 ◽  
Vol 657 ◽  
pp. 1-25 ◽  
Author(s):  
Natarajan Senthilkumar ◽  
Mohammad Luqman
Keyword(s):  
Thermal Stability ◽  
Liquid Crystalline ◽  
Heterocyclic Ring ◽  
Chain Extender ◽  
Plastic Electronics ◽  
Major Disadvantage ◽  
Ring Structures ◽  
A Chain ◽  
Multifunctional Polymers ◽  
Advanced Applications

The combination of the concept of metallopolymers with urethane chemistry offers a versatile approach for the synthesis of new polyurethane materials. Polyurethanes are a distinct class of materials with tremendous industrial importance, and it is of interest to develop these materials with modified thermal and liquid crystalline behavior for advanced applications. Generally, polyurethanes suffer a major disadvantage of poor thermal stability. This can be improved upon by chemical modification of their structures by the incorporation of thermally stable heterocyclic ring structures along with transition metals. Metal-containing polyurethanes prepared from a polymeric diol, diisocyanate and a metal containing diol (metallodiol and metallomesogenic diol) as a chain extender are attracting contemporary research interest. The addition of a polymeric diol (polyol) induces flexibility to the polyurethane by reducing the glass transition temperature, increases its solubility and imparts elastomeric properties. Multifunctional polymers are materials poised for applications in different avenues with preference for plastic electronics. An introduction-cum-overview of synthesis and applications of metal-containing polyurethanes is presented in this chapter.

Liquid crystalline moiety-assisted perpendicular orientation of cylindrical domains within P4VP-b-PMA(Az) films with high aspect ratio

Soft Matter ◽  
2018 ◽  
Vol 14 (35) ◽  
pp. 7107-7112 ◽  
Author(s):  
Ting Qu ◽  
Song Guan ◽  
Chen Zhang ◽  
Xiaoxiong Zheng ◽  
Yongbin Zhao ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Liquid Crystalline ◽  
Perpendicular Orientation ◽  
Cylindrical Domains

Block copolymer (BCP) films with perpendicularly aligned cylindrical domains of high aspect ratio have important applications in diverse fields.

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