Reversible temperature-controlled gelation in mixtures of pNIPAM microgels and non-ionic polymer surfactant

Fussell, S L; Bayliss, Kate; Coops, C; Matthews, Lauren; Li, W; Briscoe, Wuge H.; Faers, Malcolm A.; Royall, C. Patrick; Duijneveldt, Jeroen S. van

doi:10.1039/c9sm01299k

Cited by 17 publications

(53 citation statements)

References 52 publications

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“…The second effect, which drives the gelation in our system [4], is that upon heating above the volume phase transition temperature, the micelles associate with the microgels due to hydrophobic interactions, which leads to the microgel particles aggregating and undergoing gelation (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

“…Often more complex behaviour can be observed, due for example to changes in hydrophobicity * Correspondence email address: sian.fussell@bristol.ac.uk as a function of temperature between different species in the system. The system of interest here is a mixture of microgel particles and triblock copolymer micelles, which exhibits a complex response to temperature, in addition to a composition dependent phase behaviour typical of soft materials [4][5][6][7][8]. Systems that are capable of triggered gelation or viscosity-switchable materials are sort after for reconstructive surgery and drug delivery applications [9].…”

Section: Introductionmentioning

confidence: 99%

“…Our model system is a mixture of microgels and micelle-forming triblock copolymers which exhibits a complex response to temperature [4]. Microgels are colloidal particles comprised of a cross linked polymer [35][36][37][38][39][40] which exhibit some similar phenomena to hard colloids [39,41,42].…”

Section: Introductionmentioning

confidence: 99%

“…1). Thus, here, the system is effectively quenched by increasing temperature [4], in a manner reminiscent of the mixtures of colloids and nonabsorbing polymers noted above [3]. Here, we explore the response of our system to time-dependent temperature protocols.…”

Section: Introductionmentioning

confidence: 99%

“…The micelles are represented by the pink circles. [4] This paper is organised as follows: in section 2 we show our methods, in section IV, we present our main findings including the phase behaviour, control over phase using quench rates and detailed characteristics of our system, including structure and droplet growth kinetics.…”

Section: Introductionmentioning

confidence: 99%

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Controlling phase separation in microgel-polymeric micelle mixtures using variable quench rates

Fussell¹,

Royall²,

Duijneveldt³

2021

Preprint

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We investigate the temperature dependent phase behaviour of mixtures of poly(Nisopropylacrylamide) (pNIPAM) microgel colloids and a triblock copolymer (PEO-PPO-PEO) surfactant, which undergoes micellisation. Gelation in these systems results from an increase in temperature. Here we alter the heating rate and observe that the mechanism for aggregation changes from one of depletion of the microgels by the micelles at low temperatures to association of the two species at high temperatures. We use this to access multiple structures at one microgel concentration. Samples with a micelle concentration above 7 wt% were found to demix into phases rich and poor in microgel particles at temperatures below 33 • C, under conditions where the microgels particles are partially swollen. Under rapid heating full demixing is bypassed and gel networks are formed instead. The temperature history of the sample therefore allows for kinetic selection between different final structures, which may be metastable.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Controlling phase separation in microgel-polymeric micelle mixtures using variable quench rates

Fussell¹,

Royall²,

Duijneveldt³

2021

Preprint

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Pearl‐Like Sheen in Soft Capsules: An Unusual Optical Effect that is Reversibly Induced by Temperature

Rath,

Fear,

Woehl

et al. 2023

Adv Funct Materials

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A pearl-like sheen (i.e., pearlescence) is seen in many natural materials like nacre and in some commercial paints and cosmetics. This phenomenon is attributed to the interaction of light with plate-like particles in the material. Here, for the first time, pearlescence is demonstrated in soft millimeterscale capsules that contain no plate-like particles. The capsules have a thin (~500 µm) outer shell of N-isopropylacrylamide (NIPA) hydrogel, which has a lower critical solution temperature (LCST) of 32 °C. When a transparent NIPA-shelled capsule is heated above this LCST, it turns pearlescent. The effect is reversible, with the transparent state being recovered upon cooling. This is the first example of reversible pearlescence in any solid. Specular reflectance measurements show that the pearlescence of the capsules is comparable to that of natural pearls. Pearlescence is not observed in NIPA hydrogels; it arises only in NIPA-shelled capsules, and that too only when the shell is thin. Above its LCST, the NIPA shell shrinks and gets stretched, and nanoscale NIPA-rich domains arise within this shell, which induce the pearlescence. This study sheds fresh insight into the nature of pearlescence, on how it can be tuned, and on how this property can be introduced into various soft materials.

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Injectable controlled‐release systems for the prevention and treatment of infectious diseases

Kunkel,

McHugh

2023

J Biomedical Materials Res

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Pharmaceutical drugs, including vaccines, pre‐ and post‐exposure prophylactics, and chronic drug therapies, are crucial tools in the prevention and treatment of infectious diseases. These drugs have the ability to increase survival and improve patient quality of life; however, infectious diseases still accounted for more than 10.2 million deaths in 2019 before the COVID‐19 pandemic. High mortality can be, in part, attributed to challenges in the availability of adequate drugs and vaccines, limited accessibility, poor drug bioavailability, the high cost of some treatments, and low patient adherence. A majority of these factors are logistical rather than technical challenges, providing an opportunity for existing drugs and vaccines to be improved through formulation. Injectable controlled‐release drug delivery systems are one class of formulations that have the potential to overcome many of these limitations by releasing their contents in a sustained manner to reduce the need for frequent re‐administration and improve clinical outcomes. This review provides an overview of injectable controlled drug delivery platforms, including microparticles, nanoparticles, and injectable gels, detailing recent developments using these systems for single‐injection vaccination, long‐acting prophylaxis, and sustained‐release treatments for infectious disease.

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Reversible temperature-controlled gelation in mixtures of pNIPAM microgels and non-ionic polymer surfactant

Abstract: We investigate the reversible, binary gelation of poly(N-isopropylacrylamide) (pNIPAM) microgels in the presence of triblock-copolymer (PEO–PPO–PEO type) surfactant. Confocal microscopy highlights that both polymers are present in the gel network.

Cited by 17 publications

References 52 publications

Controlling phase separation in microgel-polymeric micelle mixtures using variable quench rates

Controlling phase separation in microgel-polymeric micelle mixtures using variable quench rates

Pearl‐Like Sheen in Soft Capsules: An Unusual Optical Effect that is Reversibly Induced by Temperature

Injectable controlled‐release systems for the prevention and treatment of infectious diseases

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