Abstract
Oil-soluble poly(meth)acrylate-based polymers play a vital role in the thermorheological modification of a wide variety of lubricants and formulated consumer products, where increased viscosity at elevated temperatures ensures sufficient viscosity over a broad temperature range. The assumed mechanism of viscosity modification for many such polymers is based on temperature-induced swelling due to marginal solvent quality. Although this mechanism is widely accepted, direct and consistent experimental proof is limited due to a lack of structural characterization over a wide temperature range. Additionally, the effect of polymer architecture on the temperature-dependent solution behavior is not fully understood, despite the trend toward branched polymers in recent years. Here, we provide a comprehensive set of data relying on detailed temperature-dependent viscosity measurements, dynamic light scattering (DLS), and small-angle neutron scattering (SANS) experiments to confirm the existence of temperature-induced coil expansion for industrially relevant poly(stearyl methacrylate-co-methyl methacrylate) (p(SMA-co-MMA)) polymers with various architectures including linear, randomly branched, and star-shaped topologies. Compared to the linear and randomly branched polymers, the degree of coil expansion for the star-shaped additives is significantly lower. Regardless of the polymer architecture, the propensity to undergo temperature-induced chain swelling proved to be highly specific toward the type of base oil, underlining the sensitive interplay between polymer and oil chemistry required for designing successful thermorheological modifiers.
Original language | English |
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Pages (from-to) | 5473-5483 |
Number of pages | 11 |
Journal | Macromolecules |
Volume | 54 |
Issue number | 12 |
DOIs | |
Publication status | Published - 22 Jun 2021 |
Bibliographical note
Funding Information:The research reported was partially supported by the MRSEC program of the National Science Foundation (NSF) Materials Research Science and Engineering Center at UC Santa Barbara, DMR-1720256 (IRG-3). The use of shared experimental facilities of the UCSB MRSEC DMR-1720256 is also acknowledged; the UCSB MRSEC is a member of the Materials Research Facilities Network ( www.mrfn.org ). The authors would also like to thank the Mitsubishi Chemical Center for Advanced Materials for support. The rheometer used for viscosity measurements was made possible through a collaborative agreement with Anton Paar through their VIP academic program. The authors acknowledge Michael Burroughs for assistance in configuration of the rheometer for combined convection oven-dual-motor operation. Gwen Zhang, Nino Ruocco, and Patrick Corona are greatly thanked for performing the temperature-dependent SANS measurements and fruitful discussions. Charlotte Dai is acknowledged for assistance during the synthesis of the employed polymers. This work benefited from the use of the SasView application, originally developed under NSF award DMR-0520547. SasView contains code developed with funding from the European Union’s Horizon 2020 research and innovation program under the SINE2020 project, grant agreement no. 654000.
Publisher Copyright:
© 2021 American Chemical Society. All rights reserved.
Funding
The research reported was partially supported by the MRSEC program of the National Science Foundation (NSF) Materials Research Science and Engineering Center at UC Santa Barbara, DMR-1720256 (IRG-3). The use of shared experimental facilities of the UCSB MRSEC DMR-1720256 is also acknowledged; the UCSB MRSEC is a member of the Materials Research Facilities Network ( www.mrfn.org ). The authors would also like to thank the Mitsubishi Chemical Center for Advanced Materials for support. The rheometer used for viscosity measurements was made possible through a collaborative agreement with Anton Paar through their VIP academic program. The authors acknowledge Michael Burroughs for assistance in configuration of the rheometer for combined convection oven-dual-motor operation. Gwen Zhang, Nino Ruocco, and Patrick Corona are greatly thanked for performing the temperature-dependent SANS measurements and fruitful discussions. Charlotte Dai is acknowledged for assistance during the synthesis of the employed polymers. This work benefited from the use of the SasView application, originally developed under NSF award DMR-0520547. SasView contains code developed with funding from the European Union’s Horizon 2020 research and innovation program under the SINE2020 project, grant agreement no. 654000.