scholarly journals Polybutadiene Vitrimers with Tunable Epoxy Ratios: Preparation and Properties

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4157
Author(s):  
Liqian Zhu ◽  
Li Xu ◽  
Suyun Jie ◽  
Bogeng Li

Traditional crosslinked diene rubber has excellent thermal–mechanical properties and solvent resistance, yet it is incapable of being recycled via universal molding or injecting. Vitrimers, a new class of covalently crosslinked polymer networks, can be topologically rearranged with the associative exchange mechanism, endowing them with thermoplasticity. Introducing the concept of vitrimers into crosslinked networks for the recycling of rubbers is currently an attractive research topic. However, designing tailored rubber vitrimers still remains a challenge. Herein, polybutadiene (PB) vitrimers with different structures were prepared via partial epoxidation of double bonds and ring-opening esterification reactions. Their mechanical and relaxation properties were investigated. It was found that the increasing crosslinking density can increase tensile strength and activation energy for altering the network topology. The influence of side-group effects on their relaxation properties shows that an increase in the number of epoxy groups on the polybutadiene chain can increase the chance of an effective exchange of disulfide units. This work provides a simple network design which can tune vitrimer properties via altering the crosslinking density and side-group effects.

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1674
Author(s):  
Dongyoung Kim ◽  
Iqubal Hossain ◽  
Yeonho Kim ◽  
Ook Choi ◽  
Tae-Hyun Kim

In this study, precursor molecules based on PEG/PPG and polydimethylsiloxane (PDMS), both widely used rubbery polymers, were copolymerized with bulky adamantane into copolymer membranes. Ring-opening metathesis polymerization (ROMP) was employed during the polymerization process to create a structure with both ends crosslinked. The precursor molecules and corresponding polymer membranes were characterized using various analytical methods. The polymer membranes were fabricated using different compositions of PDMS and adamantane, to determine how the network structure affected their gas separation performance. PEG/PPG, in which CO2 is highly soluble, was copolymerized with PDMS, which has high permeability, and adamantane, which controlled the crosslinking density with a rigid and bulky structure. It was confirmed that the resulting crosslinked polymer membranes exhibited high solubility and diffusivity for CO2. Further, their crosslinked structure using ROMP technique made it possible to form good films. The membranes fabricated in the present study exhibited excellent performance, i.e., CO2 permeability of up to 514.5 Barrer and CO2/N2 selectivity of 50.9.


2007 ◽  
Vol 129 (3) ◽  
pp. 506-507 ◽  
Author(s):  
Jinqi Xu ◽  
David A. Bohnsack ◽  
Michael E. Mackay ◽  
Karen L. Wooley

RSC Advances ◽  
2015 ◽  
Vol 5 (23) ◽  
pp. 17514-17518 ◽  
Author(s):  
Roberto Martin ◽  
Alaitz Rekondo ◽  
Alaitz Ruiz de Luzuriaga ◽  
Antxon Santamaria ◽  
Ibon Odriozola

Is it possible to blend two immiscible polymer networks starting from their cured state? A simple thermomechanical approach permits blending two dynamically crosslinked polymer networks, to give blends with superior mechanical properties.


2001 ◽  
Vol 709 ◽  
Author(s):  
Peter Strohriegl ◽  
Doris Hanft ◽  
Markus Jandke ◽  
Thomas Pfeuffer

ABSTRACTReactive mesogenes posess polymerizable groups attached to a rigid, liquid crystalline core. From such molecules, densely crosslinked networks in which the liquid crystalline order is permanentely fixed can be formed by photopolymerization.Our major synthetic goal was the formation of glass forming reactive mesogenes. Such compounds do not crystallize upon cooling but vitrify and form supercooled LC-phases ('LC-glasses'). They exhibit broad LC-phases and enable us to carry out photopolymerization in a broad range of temperatures.We have systematically investigated how the topology of the reactive mesogenes influences the stability of the resulting glasses. Comparing twin molecules with three- and four-armed stars we found that the supercooled LC-phase in the three-armed stars has a stability superior to both twin molecules and four-armed stars. In the three-armed star Triple-4 with a suitable substituent pattern the supercooled LC-phase is stable at room temperature for at least nine months. Doped with suitable chiral molecules the glass forming nematics form cholesteric phases which were used for cholesteric polymer networks and for polarization holograms with one s-and one p-polarized writing beam.Furthermore we have extended our synthetic efforts to reactive mesogenes with three or five conjugated fluorene units as LC-core. After orientation, the mesogenes were photocrosslinked and used as active layer in OLEDs that emit highly polarized blue light.


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