Title: Spectroscopic Signatures of MQ-Resins in Silicone Elastomers

Abstract

Polysiloxane elastomers have a large application space due to their versatile cross-linking chemistry and highly tunable physical and mechanical properties. One approach for improving the mechanical integrity of commercial polysiloxane “silicone” elastomers while maintaining their optical transparency is the addition of small, silicone-resin molecules to the network. However, both the poly(dimethylsiloxane) (PDMS) network and the silicone-resin particles have an amorphous structure and complex chemistry, which makes the characterization of their structural properties and segmental network dynamics difficult. Here, we report the synthesis and characterization of a series of model silicone networks modified with a specific class of silicone-resin known as MQ-resin using Raman and advanced nuclear magnetic resonance (NMR) spectroscopy methods. Raman spectroscopy was successfully used to quantify the contribution of the MQ-resin to the network, to determine the type of MQ-resin present in the network, and to investigate the completeness of the network cross-linking reaction. Furthermore, solid-state and 1H double-quantum (DQ) NMR spectroscopies were used not only as a detection method for the MQ-resins but also to quantify changes in the segmental dynamics of the network as a function of MQ-resin concentration. The combination of Raman and NMR spectroscopies describes a series of samples where the MQ-resin particles andmore » PDMS chains maintain their independent segmental dynamics up to high concentrations of MQ-resins (40–50% MQ), where the physical properties of the resin dominate the physical properties of the overall network. The results from our spectroscopic analyses are consistent with the results from macroscopic characterization techniques such as solvent uptake and mechanical testing. The spectroscopic insights into the structure–property relationships of PDMS-MQ composites presented in this study are a valuable tool not only for the synthesis and reverse engineering of future generations of commercial silicone elastomers but also for understanding the mechanisms of aging and degradation over the material lifetime.« less

Authors:

Sawvel, April M.  ^[1];

• Search DOE PAGES for author "Sawvel, April M."
• Search DOE PAGES for ORCID "0000-0002-8810-807X"

Crowhurst, Jonathan C. ^[1]; Mason, Harris E.  ^[1];

• Search DOE PAGES for author "Mason, Harris E."
• Search DOE PAGES for ORCID "0000-0002-1840-0550"

Oakdale, James S. ^[1]; Ruelas, Samantha ^[1]; Eshelman, Hannah V. ^[1]; Maxwell, Robert S.  ^[1]

• Search DOE PAGES for author "Maxwell, Robert S."
• Search DOE PAGES for ORCID "0000-0002-0380-7382"

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+ Show Author Affiliations

1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Publication Date:

Fri Apr 23 00:00:00 EDT 2021

Research Org.:

Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1785911

Report Number(s):

LLNL-JRNL-817509
Journal ID: ISSN 0024-9297; 1027351

Grant/Contract Number:  

AC52-07NA27344

Resource Type:

Accepted Manuscript

Journal Name:

Macromolecules

Additional Journal Information:

Journal Volume: 54; Journal Issue: 9; Journal ID: ISSN 0024-9297

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Raman spectroscopy; nuclear magnetic resonance spectroscopy; silicones; nucleic acid structure; materials