## Abstract

We prepared five pairs of hydrogenous and deuterated ring polystyrene samples over a wide range of molecular weights (10 kg/mol ≤ M_{w} ≤ 400 kg/mol) and investigated their chain conformations in bulk by small-angle neutron scattering (SANS) measurements. From the SANS profiles obtained, we estimated the radii of gyration R_{g} of the ring polymers by the Guinier approximation. R_{g} can be related to the degree of polymerization N as R_{g} ∼ N^{0.47}. This scaling exponent ν = 0.47 ± 0.01 is evidently smaller than that for the Gaussian chains (ν = 0.50) but higher than previous experimental reports (ν = 0.42-0.43). Then our data were compared with various simulation and experimental data by introducing the entanglement degree of polymerization N_{e} for linear polymers as a normalized parameter. R_{g} of three smaller rings, i.e., R-10, R-30, and R-70, where the numbers denote molecular weights in kg/mol unit, are in good agreement with simulation results, while two larger rings, R-100 and R-400, exhibit higher R_{g} values than the simulations. Considering that the latter two higher molecular weight samples include maximum 3% of linear contamination, their effects on chain dimension were calculated. As a result, it has been confirmed that 3% of linear contaminations can overestimate R_{g} of rings as much as 6% for R-100 and 12% for R-400. Thus, R_{g} for pure large rings should be considerably lower than the present experimental values. We conclude Flory's exponent v in R_{g} ∼ N^{v} for rings may not be constant but rather show molecular weight dependence due to their topological constraint.

Original language | English |
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Pages (from-to) | 1539-1548 |

Number of pages | 10 |

Journal | Macromolecules |

Volume | 51 |

Issue number | 4 |

DOIs | |

Publication status | Published - Feb 27 2018 |

## All Science Journal Classification (ASJC) codes

- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry