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Intra- and Interchain Correlations in Polymer Nanocomposites: A Small-Angle Neutron Scattering Extrapolation Method
Nicolas Jouault1, Jacques Jestin2
1Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire PHENIX, Case 51, 4 place Jussieu, F-75005 Paris, France.
ACS Macro Letters
|June 5, 2022
Summary
This study introduces a new small-angle neutron scattering (SANS) extrapolation method to analyze polymer nanocomposites (PNCs). The technique reveals chain domains within nanoparticle clusters, driven by excluded volume effects, offering new insights into polymer chain conformation.
Area of Science:
- Materials Science
- Polymer Science
- Neutron Scattering
Background:
- Polymer nanocomposites (PNCs) are advanced materials with unique properties.
- Understanding nanoparticle (NP) influence on polymer chain conformation is crucial for material design.
- Previous studies using zero average contrast (ZAC) had limitations in analyzing interchain correlations.
Purpose of the Study:
- To apply a novel small-angle neutron scattering (SANS) extrapolation method to investigate NP effects on polymer chain conformation in PNCs.
- To determine both intrachain structure factor (S1(q)) and interchain correlations (S2(q)) in PNCs.
- To validate the new method using silica/polystyrene (PS) PNCs and compare with ZAC measurements.
Main Methods:
- Application of a SANS extrapolation method utilizing a statistical hydrogenated (H)/deuterated (D) polymer matrix with added labeled chains (H).
- Extrapolation to zero H content to isolate the intrachain structure factor (S1(q)) and interchain correlations (S2(q)).
- Validation on silica/polystyrene (PS) polymer nanocomposites and comparison with prior zero average contrast (ZAC) data.
Main Results:
- The study found no significant changes in the radius of gyration (Rg) or interchain interactions due to NP presence.
- Evidence of chain domains with reduced density within NP clusters was observed, attributed to excluded volume effects.
- The extrapolation method confirmed that low-q scattering anomalies originate from polymer chains, not unmatched NPs.
Conclusions:
- The novel SANS extrapolation method provides access to both S1(q) and S2(q), offering a more comprehensive analysis of PNCs.
- Excluded volume effects lead to the formation of low-density chain domains within NP clusters.
- This research clarifies the origin of scattering behavior in PNCs, attributing unexpected low-q scattering to polymer chain dynamics.
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