Comb-branch polyethers

MD simulations of comb-branch polyethers of the structure shown in Fig. 7.14 (PEPE5) have been performed [60]. SPEs formed from this comb-branch polymer have also been studied experimentally [70-72]. A comparison of the ionic conductivity of SPEs with LiTFSI and this comb-branch polymer from simulation and experiment, along with the conductivity of a linear PEO SPE with same salt concentration is shown in Fig. 7.14 [60]. Good agreement between experiment and simulation is apparent. Furthermore, the conductivity of the comb-branch SPE is very similar to that of the linear PEO SPE. The slightly higher conductivity in the linear PEO SPE is facilitated by the lower molecular weight (2,380 Da) of the linear polymer compared to the comb-branch (around 6,000 Da). 

Analysis of the MD simulations of the PEPE5 reveal that Li" occurs primarily by hopping of the cation from one side chain to another [60]. The six oxygen atoms of the side chains facilitated coordination of Li", as anticipated. However, a fraction of Li" cations are partially coordinated by the polyether backbone. These cations have very slow dynamics and do not contribute appreciably to Li" motion. The slow dynamics of cations partially coordinated by the chain backbone can be understood by considering conformational dynamics in the comb-branch polymer. Figure 7.15 shows conformational relaxation time, based on... 

Comb-branched copolymer and block copolymer architectures are similar in that they are generally based on short polyether chains supported in some manner to give the material its mechanical stability. Success has been variable in attempts to... 

Figure 6a and c show typical structures of silicone surfactants for the production of polyurethane foam, i.e., comb-like and branched siloxanes. Siloxanes that are modified with polyether groups are important surfactants for rigid, ester, or flexible slabstock foams. 

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