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Segregation of mass at the periphery of N -isopropylacrylamide-co-acrylic-acid microgels at high temperatures

Journal Article · · Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
 [1];  [2];  [1];  [3];  [4];  [1];  [1]
  1. Georgia Inst. of Technology, Atlanta, GA (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Shinsegae International, Seoul (South Korea)
  4. Hanyang Univ., Gyeonggi (South Korea)
Here, we investigate poly(N-isopropylacrylamide) (pNIPAM) microgels randomly copolymerized with large mol % of protonated acrylic acid (AAc), finding that above the lower critical solution temperature the presence of the acid strongly disrupts pNIPAM's collapse, leading to unexpected new behavior at high temperatures. We see a dramatic increase in the ratio between the radius of gyration and the hydrodynamic radius above the theoretical value for homogeneous spheres, and a corresponding increase of the network length scale, which we attribute to the presence of a heterogeneous polymer distribution that forms due to frustration of pNIPAM's coil-to-globule transition by the AAc. Finally, we analyze this phenomenon using a Debye-Bueche-like scattering contribution as opposed to the Lorentzian term often used, interpreting the results in terms of mass segregation at the particle periphery.
Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
1265870
Alternate ID(s):
OSTI ID: 1222430
Journal Information:
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics, Journal Name: Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics Journal Issue: 3 Vol. 92; ISSN 1539-3755; ISSN PLEEE8
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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Investigation on the structure of temperature-responsive N-isopropylacrylamide microgels containing a new hydrophobic crosslinker journal March 2015
Structural modifications in the swelling of inhomogeneous microgels by light and neutron scattering journal November 2002
Temperature-sensitive poly(N-Isopropyl-Acrylamide) microgel particles: A light scattering study journal November 2008

Cited By (2)

Synthesis of smart dual-responsive microgels: correlation between applied surfactants and obtained particle morphology journal January 2019
Tuning the Swelling Properties of Smart Multiresponsive Core-Shell Microgels by Copolymerization journal July 2019

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