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Hallett JE, Grillo I, Smith GN. A Neutron Scattering Study of the Structure of Poly(dimethylsiloxane)-Stabilized Poly(methyl methacrylate) (PDMS-PMMA) Latexes in Dodecane. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:2071-2081. [PMID: 32008323 DOI: 10.1021/acs.langmuir.9b03911] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Hard-sphere particles in nonpolar solvents are an essential tool for colloid scientists. Sterically stabilized poly(methyl methacrylate) (PMMA) particles have long been used as the exemplary hard-sphere system. However, neither the particles themselves nor the poly(12-hydroxystearic acid) (PHSA) stabilizer necessary to prevent aggregation in nonpolar solvents are commercially available. To counter this, several alternatives have been proposed. In recent years, there has been an increased interest in poly(dimethylsiloxane) (PDMS) stabilizers as a commercially available alternative to PHSA, yet the structure of particles made in this way is not as well understood as those produced using PHSA. In this work, we employ small-angle neutron scattering to determine the internal structure of PDMS-stabilized PMMA particles, synthesized with and without an additional crosslinking agent. We report data consistent with a homogeneous PMMA core with a linearly decaying PDMS shell. The thickness of the shell was in excess of 50 nm, thicker than the PHSA layer typically used to stabilize PMMA but consistent with reports of the layer thickness for similar molecular weight PDMS at planar surfaces. We also show that the amount of the hydrogenous material in the particle core of the crosslinked particles notably exceeds the amount of added ethylene glycol dimethacrylate crosslinker, suggesting some entrapment of the PDMS stabilizer in the PMMA matrix.
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Affiliation(s)
- James E Hallett
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, U.K
| | - Isabelle Grillo
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Gregory N Smith
- Department of Chemistry, University of Sheffield, Brook Hill, Sheffield, South Yorkshire S3 7HF, U.K
- Niels Bohr Institute, H. C. Ørsted Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
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Experimental synthesis and characterization of rough particles for colloidal and granular rheology. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.04.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Ashrafizadeh M, Tam KC, Javadi A, Abdollahi M, Sadeghnejad S, Bahramian A. Synthesis and physicochemical properties of dual-responsive acrylic acid/butyl acrylate cross-linked nanogel systems. J Colloid Interface Sci 2019; 556:313-323. [PMID: 31454623 DOI: 10.1016/j.jcis.2019.08.066] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 08/16/2019] [Accepted: 08/17/2019] [Indexed: 12/22/2022]
Abstract
HYPOTHESIS A cross-linked amphiphilic nanogel containing a high mole% of hydrophilic pH-responsive moiety can provide enhanced functionality regarding stimuli-responsiveness, water-dispersibility, hydrophobic substance loading, and structural stability under harsh environmental conditions. These nanogels could be synthesized using a one-pot procedure for large-scale applications. Moreover, the interplay of various interaction forces in these colloidal systems is being investigated. EXPERIMENTS Model nanogels consisting of acrylic acid-butyl acrylate-ethylene glycoldimethacrylate were synthesized using an emulsion copolymerization via a seeded semi-batch process under an acidic condition. The structures were assessed by Fourier transform infrared spectroscopy and potentiometric-conductometric titrations. Zeta potential, field-emission scanning electron microscopy, and transmission electron microscopy were used to evaluate the dispersion stability, size distribution, and structural distribution, respectively. Their stimuli-responsive behavior was studied by combining static and dynamic light scattering and titration analyses. FINDINGS Monodisperse nanospheres of approximately 150 nm were successfully prepared by implementing a one-pot practical pathway. These nanogels displayed a dual thermo- and pH-responsive behavior, reflecting the high efficiency of physical cross-linking make it ideal for drug delivery and oil industry applications. Moreover, a novel symmetric pH-activated morphology transformation behavior was revealed. Accordingly, a compositional distribution was proposed and assessed by exploring the polymerization process.
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Affiliation(s)
- Marjan Ashrafizadeh
- Department of Chemical Engineering, College of Engineering, University of Tehran, 11155/4563 Tehran, Iran.
| | - Kam Chiu Tam
- Department of Chemical Engineering, Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
| | - Aliyar Javadi
- Department of Chemical Engineering, College of Engineering, University of Tehran, 11155/4563 Tehran, Iran; Max Planck Institute of Colloids and Interfaces Potsdam/Golm, Germany.
| | - Mahdi Abdollahi
- Department of Polymer Reaction Engineering, Faculty of Chemical Engineering, Tarbiat Modares University, 14115-114 Tehran, Iran.
| | - Saeid Sadeghnejad
- Department of Petroleum Engineering, Faculty of Chemical Engineering, Tarbiat Modares University, 14115-114 Tehran, Iran.
| | - Alireza Bahramian
- Department of Chemical Engineering, College of Engineering, University of Tehran, 11155/4563 Tehran, Iran.
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Smith GN, Ahualli S, Delgado ÁV, Gillespie DAJ, Kemp R, Peach J, Pegg JC, Rogers SE, Shebanova O, Smith N, Eastoe J. Charging Poly(methyl Methacrylate) Latexes in Nonpolar Solvents: Effect of Particle Concentration. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:13543-13553. [PMID: 29064706 DOI: 10.1021/acs.langmuir.7b02257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The electrophoresis of a well-established model system of charged colloids in nonpolar solvents has been studied as a function of particle volume fraction at constant surfactant concentration. Dispersions of poly(12-hydroxystearic acid)-stabilized poly(methyl methacrylate) (PMMA) latexes in dodecane were prepared with added Aerosol OT surfactant as the charging agent. The electrophoretic mobility (μ) of the PMMA latexes is found to decrease with particle concentration. The particles are charged by a small molecule charging agent (AOT) at finite concentration, and this makes the origin of this decrease in μ unclear. There are two suggested explanations. The decrease could either be due to the reservoir of available surfactant being exhausted at high particle concentrations or the interactions between the charged particles at high particle number concentrations. Contrast-variation small-angle neutron scattering measurements of PMMA latexes and deuterated AOT-d34 surfactant in latex core contrast-matched solvent were used to study the former, and electrokinetic modeling was used to study the latter. As the same amount of AOT-d34 is found to be incorporated with the latexes at all volume fractions, the solvodynamic and electrical interactions between particles are determined to be the explanation for the decrease in mobility. These measurements show that, for small latexes, there are interactions between the charged particles at all accessible particle volume fractions and that it is necessary to account for this to accurately determine the electrokinetic ζ potential.
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Affiliation(s)
- Gregory N Smith
- School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Silvia Ahualli
- Department of Applied Physics, School of Science, University of Granada , 18071 Granada, Spain
| | - Ángel V Delgado
- Department of Applied Physics, School of Science, University of Granada , 18071 Granada, Spain
| | - David A J Gillespie
- School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Roger Kemp
- Merck Chemicals Ltd, University Parkway , Chilworth, Southampton SO16 7QD, United Kingdom
| | - Jocelyn Peach
- School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Jonathan C Pegg
- School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Sarah E Rogers
- ISIS-STFC, Rutherford Appleton Laboratory , Chilton, Oxon OX11 0QX, United Kingdom
| | - Olga Shebanova
- Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus , Chilton, Didcot OX11 0DE, United Kingdom
| | - Nathan Smith
- Merck Chemicals Ltd, University Parkway , Chilworth, Southampton SO16 7QD, United Kingdom
| | - Julian Eastoe
- School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, United Kingdom
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