High Resolution Zeta Potential Measurements: Analysis of Multi-component Mixtures

Connah, Malcolm T.; Kaszuba, Michael; Morfesis, Ana

doi:10.1081/dis-120015369

Cited by 15 publications

(10 citation statements)

References 3 publications

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“…In FFR the field is reversed 25-50 times per second, thus making electro-osmosis insignificant and providing accurate mean mobility value. The SFR contributes extra resolution for a better distribution analysis [55,56]. The frequency shift ∆ν due to the mobility µ of the scattered particles under the action of the applied field E is measured by comparing the phase Φ of the scattered signal to that of a reference one, since Φ = ν• time.…”

Section: Electrophoretic Measurementsmentioning

confidence: 99%

Study of network composition in interpenetrating polymer networks of poly(N isopropylacrylamide) microgels: The role of poly(acrylic acid)

Nigro

Angelini

Rosi

et al. 2019

Journal of Colloid and Interface Science

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Hypothesis:The peculiar swelling behaviour of poly(N-isopropylacrylamide) (PNIPAM)-based responsive microgels provides the possibility to tune both softness and volume fraction with temperature, making these systems of great interest for technological applications and theoretical implications. Their intriguing phase diagram can be even more complex if poly(acrylic acid) (PAAc) is interpenetrated within PNIPAM network to form Interpenetrating Polymer Network (IPN) 1 microgels that exhibit an additional pH-sensitivity. The effect of the PAAc/PNIPAM polymeric ratio on both swelling capability and dynamics is still matter of investigation.Experiments: Here we investigate the role of PAAc in the behaviour of IPN microgels across the volume phase transition through dynamic light scattering (DLS) 2 , transmission electron microscopy (TEM) 3 and electrophoretic measurements as a function of microgel concentration and pH.Findings: Our results highlight that aggregation is favored at increasing weight concentration, PAAc content and pH and that a crossover PAAc content C * PAAc 4 exists above which the ionic charges on the microgel become relevant. Moreover we show that the softness of IPN microgels can be tuned ad hoc by changing the PAAc/PNIPAM ratio. These findings provide new insights into the possibility * Corresponding authors. C PAAc : weight content (%) of the PAAc network within each IPN microgel to control experimentally aggregation properties, charge and softness of IPN microgels by varying PAAc content. Introduction The novel class of responsive microgels has recently become very popular since their smart responsivity to external stimuli makes them very attractive for industrial applications [1-6] and excellent model systems for exploring the exotic behaviours emerging in soft colloids due to their softness [7-9]. Their interparticle potential and their effective volume fraction can be easily managed through unusual control parameters such as temperature, pH or solvent, allowing to explore unusual phase-behaviours [10-15], significantly far from those of conventional hard colloids [16-25].The deep investigation in the last years has shown how responsive microgels based on poly(Nisopropylacrylamide) (PNIPAM) undergo a reversible Volume Phase Transition (VPT) 3 at about 305 K that drives the system from a swollen hydrated state to a shrunken dehydrated one, as a consequence of the coil-to-globule transition of NIPAM chains [26]. It has been shown that the driving force for swelling can be estimated from the properties of linear PNIPAM solutions, while the microgel elasticity opposing swelling is mainly due to the network topology dependent on the cross-linker concentration [27][28][29]. The typical swelling/shrinking behaviour of any PNIPAM-based microgel leads to intriguing phase diagrams which may be even more complex if other polymers, sensitive to different external stimuli, are copolymerized or interpenetrated to obtain multi-responsive microgels. In particular PNIPAM microgels containing poly(acrilic acid) ...

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Section: Electrophoretic Measurementsmentioning

confidence: 99%

Study of network composition in interpenetrating polymer networks of poly(N isopropylacrylamide) microgels: The role of poly(acrylic acid)

Nigro

Angelini

Rosi

et al. 2019

Journal of Colloid and Interface Science

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show abstract

“…In FFR the field is reversed 25–50 times per s, thus making electro-osmosis insignificant and providing accurate mean mobility value. The SFR contributes extra resolution for a better distribution analysis [ 86 , 87 ]. The frequency shift

due to the mobility

of the scattered particles under the action of the applied field E is measured by comparing the phase

of the scattered signal to that of a reference one, since

time.…”

Section: Experimental Methodsmentioning

confidence: 99%

Chemical-Physical Behaviour of Microgels Made of Interpenetrating Polymer Networks of PNIPAM and Poly(acrylic Acid)

et al. 2021

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Microgels composed of stimuli responsive polymers have attracted worthwhile interest as model colloids for theorethical and experimental studies and for nanotechnological applications. A deep knowledge of their behaviour is fundamental for the design of new materials. Here we report the current understanding of a dual responsive microgel composed of poly(N-isopropylacrylamide) (PNIPAM), a temperature sensitive polymer, and poly(acrylic acid) (PAAc), a pH sensitive polymer, at different temperatures, PAAc contents, concentrations, solvents and pH. The combination of multiple techniques as Dynamic Light Scattering (DLS), Raman spectroscopy, Small Angle Neutron Scattering (SANS), rheology and electrophoretic measurements allow to investigate the hydrodynamic radius behaviour across the typical Volume Phase Transition (VPT), the involved molecular mechanism and the internal particle structure together with the viscoelastic properties and the role of ionic charge in the aggregation phenomena.

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“…The phase analysis of a fast field reversal measurement leads to an average zeta potential, a measure of the effective charge of the particle including any counter ions dragged along [4].Additional TiO 2 and ZnO samples were used in these studies. As with the sizing, parameters for water were chosen, the dielectric constant of 78.5 was used.…”

Section: Methodsmentioning

confidence: 99%

Characterization of Nanoparticles by Light Scattering

Nobbmann¹,

Morfesis²

2008

MRS Proc.

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Metal oxide nanoparticles are increasingly being used to prepare new nanocrystalline materials. By controlling formulations of multicomponent metal oxides; crystal shape, structure and surface properties important in the design of new materials are gaining acceptance for many applications. Metal oxide composites are being used to design new electronic, magnetic and optical properties into material structures. Often these are formulated and processed in slurries or aqueous suspensions. A key parameter of controlling the design of such colloidal nanoparticle systems is their particle size. There are different methods by which a particle size can be obtained. Comparing stated dimensions from one method with those from another must be approached with caution: distributions in terms of volume, number or scattering intensity usually produce vastly differing results -despite expressing the exact same physical situation. Another fundamental colloidal characteristic is the zeta potential. This parameter effectively quantifies electrostatic stabilization, and can be used in formulation development to avoid instability as a result of particle-particle attraction.Both size and zeta potential are easily measured by light scattering. Small amounts of aggregates are quickly detected by dynamic light scattering (DLS). The zeta potential is rapidly measured by electrophoretic light scattering (ELS). As an example of a typical metal oxide, data for TiO 2 nanoparticles are presented.Light scattering is a versatile measurement technique and ideally suited as a metrology of choice for size and stability quantification of nano-sized materials.

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High Resolution Zeta Potential Measurements: Analysis of Multi-component Mixtures

Cited by 15 publications

References 3 publications

Study of network composition in interpenetrating polymer networks of poly(N isopropylacrylamide) microgels: The role of poly(acrylic acid)

Study of network composition in interpenetrating polymer networks of poly(N isopropylacrylamide) microgels: The role of poly(acrylic acid)

Chemical-Physical Behaviour of Microgels Made of Interpenetrating Polymer Networks of PNIPAM and Poly(acrylic Acid)

Characterization of Nanoparticles by Light Scattering

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