Effect of Diphenyl Content on Viscoelasticity of Poly(dimethyl-co-diphenyl)siloxane Melt and Network

Journal Article · Fri Feb 03 00:00:00 EST 2023 · ACS Applied Polymer Materials

DOI:https://doi.org/10.1021/acsapm.2c01979· OSTI ID:2007293

Xian, Weikang ^[1]; Liu, Chung-Hao ^[2]; Kangarlou, Behrad ^[2]; Chang, Shing-Yun ^[2]; Wu, Chao ^[2]; Cao, Yang ^[2]; Sun, Luyi ^[2]; Ma, Anson W. K. ^[2]; Nieh, Mu-Ping ^[2]; Maiti, Amitesh ^[3]; Saab, Andrew P. ^[3]; Li, Ying ^[1]

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1. Univ. of Wisconsin, Madison, WI (United States)
2. Univ. of Connecticut, Storrs, CT (United States)
3. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Polydimethylsiloxane (PDMS) is one of the most widely used polymeric materials for sealants, adhesives, lubricants, and thermal as well as electrical insulation. At low temperatures, however, PDMS is subject to crystallization that can cause deterioration in mechanical function. A common way to suppress such crystallization is through the incorporation of phenylsiloxane into the backbone of polysiloxane. Nevertheless, the introduction of phenyl components, even in small quantities, could potentially change the properties of the siloxane in a significant way. In this work, a series of mechanical tests and finite element simulations were performed to study the macroscale viscoelasticity of two poly(dimethyl-co-diphenyl)siloxane formulations in order to understand the effects of a few percent diphenyl contents on the viscoelasticity of the polysiloxane material. Here, we utilized the small-angle X-ray scattering to investigate the microscopic structures of the copolymers and broadband dielectric spectroscopy and rheology to probe the chain dynamics at the microscale. The results of these characterizations were used to inform the finite element simulations. We found that the degree of cross-linking does not significantly alter the microstructure but can profoundly affect the viscoelastic response of the copolymer networks. The corresponding hysteretic behavior is interpreted in terms of reptation-like motion and relaxation of the effective free chains in the cured polymer network. The relaxation of the copolymer chains is slowed significantly by even a small increase in the molar ratio of the diphenyl component.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Grant/Contract Number: AC52-07NA27344; SC0012704
• OSTI ID: 2007293
• Report Number(s): LLNL--JRNL-842260; 1063927
• Journal Information: ACS Applied Polymer Materials, Journal Name: ACS Applied Polymer Materials Journal Issue: 3 Vol. 5; ISSN 2637-6105
• Publisher: ACS Publications
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
aromatic compounds
copolymers
dielectric spectroscopy
diphenylsiloxane
mechanical test
nucleic acid structure
polydimethylsiloxane
rheology
silicones
viscoelasticity