Packing density, homogeneity, and regularity: Quantitative correlations between topology and thermoresponsive morphology of PNIPAM-co-PAA microgel coatings

Cutright, Camden C.; Brotherton, Zach; Alexander, Landon; Harris, Jacob L.; Shi, Kaihang; Khan, Saad A.; Genzer, Jan; Menegatti, Stefano

doi:10.1016/j.apsusc.2019.145129

Cited by 10 publications

(17 citation statements)

References 49 publications

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“…For a concentration of 1% and speed R1, it is evident that a continuous film does not form but only isolated patches of aggregated particles. This result is in agreement with the ones previously reported by other groups for microgel with a size comparable to or larger than PNIPAm b [ 52 , 62 ]. It must be noticed that the spherical shape of the particles can be still observed.…”

Section: Resultssupporting

confidence: 94%

“…These microgels are not stable in water when deposited over neutral glass [ 59 ]. On the contrary, they are stable on positively charged surface, usually obtained by PEI deposition, due to the attraction between opposite charges [ 22 , 51 , 52 , 62 , 72 ]. However, to the best of our knowledge, no specific investigation has been reported on the effect of the surface polarity.…”

Section: Resultsmentioning

confidence: 99%

“…Microgels films have been obtained by different deposition methods such as dip-coating, spin-coating, solvent evaporation, or layer-by-layer deposition [ 17 , 22 , 38 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ]. Despite the numerous advantages of these strategies, some drawbacks yet exist: (a) scarce stability when immersed in water; (b) low packing density.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, a low pack density usually results in discontinuous islands of particles or in bumped morphology films due to the sphere arrangement [ 51 , 52 , 53 , 54 , 58 , 60 , 64 ]. Only occasionally continuous and smooth films consisting of microgels, merged to a certain degree, have been reported [ 22 , 60 ] and even in these cases the particle edges are easily detectable.…”

Section: Introductionmentioning

confidence: 99%

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Formation and Stability of Smooth Thin Films with Soft Microgels Made of Poly(N-Isopropylacrylamide) and Poly(Acrylic Acid)

et al. 2020

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In this work, soft microgels of Poly(N-Isopropylacrylamide) (PNIPAm) at two different sizes and of interpenetrated polymer network (IPN) composed of PNIPAm and Poly(Acrylic Acid) (PAAc) were synthesized. Then, solutions of these different types of microgels have been spin-coated on glass substrates with different degrees of hydrophobicity. PNIPAm particles with a larger diameter form either patches or a continuous layer, where individual particles are still distinct, depending on the dispersion concentration and spin speed. On the other, PNIPAm particles with a smaller diameter and IPN particles form a continuous and smooth film, with a thickness depending on the dispersion concentration and spin-speed. The difference in morphology observed can be explained if one considers that the microgels may behave as colloidal particles or macromolecules, depending on their size and composition. Additionally, the microgel size and composition can also affect the stability of the depositions when rinsed in water. In particular, we find that the smooth and continuous films show a stimuli-dependent stability on parameters such as temperature and pH, while large particle layers are stable under any condition except on hydrophilic glass by washing at 50 °C.

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Section: Resultssupporting

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Formation and Stability of Smooth Thin Films with Soft Microgels Made of Poly(N-Isopropylacrylamide) and Poly(Acrylic Acid)

et al. 2020

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“…The desire to take advantage of microgels at the macro scale has led scientists to use microgels as building blocks to create extended two- and three-dimensional structures [ 16 , 17 , 18 , 19 , 20 ]. To obtain films and macromaterials based on microgels, various principles are used, such as adsorption or grafting on chemically modified surface [ 20 , 21 , 22 ], layer-by-layer assembly [ 19 , 23 ], and crosslinking of microgel particles citeGuan2011, Cai2008.…”

Section: Introductionmentioning

confidence: 99%

Microstructured Macromaterials Based on IPN Microgels

et al. 2021

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This study investigates the formation of microstructured macromaterials from thermo- and pH-sensitive microgels based on interpenetrating networks of poly-N-isopropylacrylamide (PNIPAM) and polyacrylic acid (PAA). Macromaterials are produced as a result of the deposition of microgel particles and subsequent crosslinking of polyacrylic acid subnetworks to each other due to the formation of the anhydride bonds during annealing. Since both PNIPAM and PAA are environment-sensitive polymers, one can expect that their conformational state during material development will affect its resulting properties. Thus, the influence of conditions of preparation for annealing (pH of the solution, the temperature of preliminary drying) on the swelling behavior, pH- and thermosensitivity, and macromaterial inner structure was investigated. In parallel, the study of the effect of the relative conformations of the IPN microgel subnetworks on the formation of macromaterials was carried out by the computer simulations method. It was shown that the properties of the prepared macromaterials strongly depend both on the temperature and pH of the PNIPAM-PAA IPN microgel dispersions. This opens up new opportunities to obtain materials with pre-chosen characteristics and environmental sensitivity.

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Surface‐Bound Microgels for Separation, Sensing, and Biomedical Applications

Cutright

Harris

Ramesh

et al. 2021

Adv Funct Materials

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This study presents a comprehensive survey of microgel-coated materials and their functional behavior, describing the complex interplay between the physicochemical and mechanical properties of the microgels and the chemical and morphological features of substrates. The cited literature is articulated in four main sections: i) properties of 2D and 3D substrates, ii) synthesis, modification, and characterization of the microgels, iii) deposition techniques and surface patterning, and iv) application of microgel-coated surfaces focusing on separations, sensing, and biomedical applications. Each section discussesby way of principles and examples -how the various design parameters work in concert to deliver functionality to the composite systems. The case studies presented herein are viewed through a multi-scale lens. At the molecular level, the surface chemistry and the monomer make-up of the microgels endow responsiveness to environmental and artificial physical and chemical cues. At the micro-scale, the response effects shifts in size, mechanical, and optical properties, and affinity towards species in the surrounding liquid medium, ranging from small molecules to cells. These phenomena culminate at the macro-scale in measurable, reversible, and reproducible effects, aiming in a myriad of directions, from lab-scale to industrial applications.

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Packing density, homogeneity, and regularity: Quantitative correlations between topology and thermoresponsive morphology of PNIPAM-co-PAA microgel coatings

Cited by 10 publications

References 49 publications

Formation and Stability of Smooth Thin Films with Soft Microgels Made of Poly(N-Isopropylacrylamide) and Poly(Acrylic Acid)

Formation and Stability of Smooth Thin Films with Soft Microgels Made of Poly(N-Isopropylacrylamide) and Poly(Acrylic Acid)

Microstructured Macromaterials Based on IPN Microgels

Surface‐Bound Microgels for Separation, Sensing, and Biomedical Applications

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