Theory of segmental orientation in amorphous polymer networks

1985 ◽  
Vol 18 (10) ◽  
pp. 1985-1991 ◽  
Author(s):  
Burak Erman ◽  
Lucien Monnerie
Keyword(s):  
Amorphous Polymer ◽  
Polymer Networks ◽  
Segmental Orientation

Ability to Control the Glass Transition Temperature of Amorphous Shape-Memory Polyesterurethane Networks by Varying Prepolymers in Molecular Mass as well as in Type and Content of Incorporated Comonomers

2009 ◽  
Vol 1190 ◽  
Author(s):  
Joerg Zotzmann ◽  
Steffen Kelch ◽  
Armin Alteheld ◽  
Marc Behl ◽  
Andreas Lendlein
Keyword(s):  
Glass Transition ◽  
Minimally Invasive Surgery ◽  
Shape Memory ◽  
Molecular Mass ◽  
Amorphous Polymer ◽  
Polymer Networks ◽  
Precise Control ◽  
Low Weight ◽  
Switching Temperature ◽  
Selection Of

AbstractThe need of intelligent implant materials for applications in the area of minimally invasive surgery leads to tremendous attention for polymers which combine degradability and shape-memory capability. Application of heat, and thereby exceeding a certain switching temperature Tsw, causes the device to changes its shape. The precise control of Tsw is particularly challenging. It was investigated in how far Tg, that can be used as Tsw, of amorphous polymer networks from star-shaped polyester macrotetrols crosslinked with a low-weight linker can be controlled systematically by incorporation of different comonomers into poly(rac-lactide) prepolymers. The molecular mass of the prepolymers as well as type and content of the comonomers was varied. The Tg could be adjusted by selection of comonomer type and ratio without affecting the advantageous elastic properties of the polymer networks.

Structure and Mechanical Properties of Rubberlike Proteins in Animals

1987 ◽  
Vol 60 (3) ◽  
pp. 417-438 ◽  
Author(s):  
John M. Gosline
Keyword(s):  
Amorphous Polymer ◽  
Polymer Networks ◽  
Random Coil ◽  
Future Research ◽  
Random Networks ◽  
Glass Transitions ◽  
Mechanical State ◽  
Protein Molecules ◽  
Polypeptide Chains ◽  
Covalent Crosslinks

Abstract Polymer networks formed from protein molecules that adopt kinetically-free, random-coil conformations are found in many animals, where they play a number of important roles. The 5 rubberlike proteins isolated and studied to date indicate that animal rubbers, like their synthetic counterparts, contain random networks which are usually stabilized by covalent crosslinks. Long-range elasticity in rubberlike proteins is based on changes in the conformational entropy of random-coil molecules. Further, these protein networks show viscoelastic glass transitions similar to all other amorphous polymer networks. Future research on protein sequences should increase our understanding of how polypeptide chains can function as random-coil molecules, and studies into the mechanical state of elastin in arterial tissues may provide important clues about the mechanisms of some forms of human disease.

scholarly journals Conversion of amorphous polymer networks to covalent organic frameworks under ionothermal conditions: a facile synthesis route for covalent triazine frameworks

2015 ◽  
Vol 3 (48) ◽  
pp. 24422-24427 ◽  
Author(s):  
Sophie Kuecken ◽  
Johannes Schmidt ◽  
Linjie Zhi ◽  
Arne Thomas
Keyword(s):  
Amorphous Polymer ◽  
Polymer Networks ◽  
Porous Polymer ◽  
Covalent Organic Frameworks ◽  
Facile Synthesis ◽  
Synthesis Route

Covalent triazine frameworks (CTFs) are prepared from amorphous, non-porous polymer networks using a facile and scalable procedure.

Insight into the crystallization of amorphous imine-linked polymer networks to 2D covalent organic frameworks

2016 ◽  
Vol 52 (18) ◽  
pp. 3690-3693 ◽  
Author(s):  
Brian J. Smith ◽  
Anna C. Overholts ◽  
Nicky Hwang ◽  
William R. Dichtel
Keyword(s):  
Growth Mechanism ◽  
Amorphous Polymer ◽  
Polymer Networks ◽  
Covalent Organic Frameworks ◽  
Rapid Formation ◽  
Insight Into

The growth mechanism of 2D imine-linked COF involves the rapid formation of an amorphous polymer, which subsequently crystallizes.

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