| 研究実績の概要 |
Based on our earlier results, for the blends with the monomer size disparity, we had hypothesized that the anomalous dependence of the tube diameter on the blend composition likely had its origin in the local packing of the monomers (beads) that comprise the polymer. To investigate this issue further, we calculated the pair correlation function (radial distribution function) of the blends of the different compositions.
From the pair correlation function we found that for the blends with the monomer size disparity, the small monomers were more likely to be found next to the large monomers and that the nonbonded large monomers were less likely to be found next to each other than expected from random mixing. This was different from the results for the blends with the stiffness disparity, where the monomer mixing was essentially random. These results suggested that the non-random mixing between the large and the small monomers could be behind the anomalous mixing rules seen in the blends with the monomer size disparity. We are currently trying to include the effects of non-random mixing on the extensions of the conventional mixing rules for the case of blends.
We have also started an investigation on the dynamics of the monomers and the chains in both in both types of blends. Initial results suggest that the relaxation time varies with the blend composition unusually for monomer size disparity blends. This implies that the chain dynamics is quite different in the case of blends with the monomer size disparity when compared to blends only with the stiffness disparity.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
We had worked on a different aspects of polymer melts as part of an earlier project. Therefore we had some experience in dealing with the issues that could cause delays. On the basis of that experience, we had anticipated and were adequately prepared to tackle for most of the problematic issues that were likely to arise. Therefore, we were able to quickly address any issues that arose before they became big problems.
However, the current pandemic situation has seriously affected visits to our collaborators for in-person discussions. While we have somewhat compensated for this by arranging web meetings, international collaborations have become more difficult as a result. We are currently trying different methods to make such collaborations more effective and also to make them run smoother.
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| 今後の研究の推進方策 |
As mentioned earlier, the monomer‐monomer pair correlation function, which quantifies how the local density varies with the intermonomer distance, indicated the following: (1) that blends with monomer size disparity exhibited non-random mixing of the monomers, while (2) similarly to single component melts, blends with chain stiffness disparity exhibited random mixing of the monomers. We are currently trying to incorporate this finding in the current extensions to blends of the entanglement ansatz for polymer melts.
In addition, also as mentioned earlier, preliminary results suggested that the dynamics of the monomers and chains in the blends with the monomer size disparity was significantly different to the chain dynamics in blends with stiffness disparity. From our results for the mixing rules, part of the reason could be the non-random of the monomers. Therefore, to focus on the effect of the monomer size disparity, we will begin with unentangled melts. We also plan to investigate the chain dynamics by systematically varying the molecular weights of both the components in the blend. After this, we plan to move on to the entangled melts.
In the meantime, we also plan to continue our earlier investigations on the phase diagram of polymer blends with monomer size disparity as a function of the monomer repulsion by varying the appropriate parameter in the truncated shifted purely repulsive Lennard‐Jones potential. This will allow us to elucidate the
effect of the intermolecular potential, if any, on the entanglement structure in blends.
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