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Town A, Niezabitowska E, Kavanagh J, Barrow M, Kearns VR, García-Tuñón E, McDonald TO. Understanding the Phase and Morphological Behavior of Dispersions of Synergistic Dual-Stimuli-Responsive Poly( N-isopropylacrylamide) Nanogels. J Phys Chem B 2019; 123:6303-6313. [PMID: 31251624 PMCID: PMC7007235 DOI: 10.1021/acs.jpcb.9b04051] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/21/2019] [Indexed: 12/14/2022]
Abstract
This work represents a detailed investigation into the phase and morphological behavior of synergistic dual-stimuli-responsive poly(N-isopropylacrylamide) nanogels, a material that is of considerable interest as a matrix for in situ forming implants. Nanogels were synthesized with four different diameters (65, 160, 310, and 450 nm) as monodispersed particles. These different samples were then prepared and characterized as both dilute (0.1 wt %) and concentrated dispersions (2-22 wt %). In the dilute form, all of the nanogels had the same response to the triggers of the physiological temperature and ionic strength. In water, the nanogels would deswell when heated above 32 °C, while they would aggregate if heated above this temperature at the physiological ionic strength. In the concentrated form, the nanogels exhibited a wide range of morphological changes, with liquid, swollen gel, shrunken gel, and aggregate structures all possible. The occurrence of these structures was dependent on many factors such as the temperature, ionic strength of the solvent, size and ζ-potential of the nanogel, and dispersion concentration. We explored these factors in detail with techniques such as visual studies, rheology, effective volume fraction, and shape factor measurement. The different-sized nanogels displayed differing phase and morphological behavior, but generally higher concentrations of the nanogels (>7 wt %) yielded gels in water with the transitions depending on the temperature. The smallest nanogel (65 nm diameter) exhibited the most unique behavior; it did not form a swollen gel at any concentration tested. Shape factor measurement for the nanogel samples showed that two of the larger three samples (160 and 310 nm) had core-shell structures with denser core cross-linking, while the smallest nanogel sample displayed a homogeneous cross-linked structure. We hypothesize that the smallest nanogels are able to undergo more extensive interpenetration compared to the larger nanogels, which meant that the smallest nanogel was not able to form a swollen gel. In the presence of salt at 12 wt %, all of the nanogels formed aggregates when heated above 35 °C due to the screening of the electrostatic stabilization by the salt. This work revealed unique behavior of the smallest nanogel with a homogeneous cross-linked structure; its phase and morphological behavior were unlike a particle dispersion, rather these were more similar to those of a branched polymer solution. In total, these findings can be used to provide information about the design of poly(N-isopropylacrylamide) nanogel dispersions for different applications where highly specific spatiotemporal control of morphology is required, for example, in the formation of in situ forming implants or for pore blocking behavior.
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Affiliation(s)
- Adam Town
- Department
of Chemistry & Materials Innovation Factory and School of Engineering
& Materials Innovation Factory, University
of Liverpool, Oxford Street, Liverpool L69 7ZD, U.K.
| | - Edyta Niezabitowska
- Department
of Chemistry & Materials Innovation Factory and School of Engineering
& Materials Innovation Factory, University
of Liverpool, Oxford Street, Liverpool L69 7ZD, U.K.
| | - Janine Kavanagh
- Department
of Earth, Ocean and Ecological Sciences, University of Liverpool, Jane Herdman Laboratories, Liverpool L69 3GP, U.K.
| | - Michael Barrow
- Anton
Paar (UK) Ltd., Unit F, The Courtyard, St. Albans AL4 0LA, U.K.
| | - Victoria R. Kearns
- Department
of Eye and Vision Science, University of
Liverpool, Liverpool L7 8TX, U.K.
| | - Esther García-Tuñón
- Department
of Chemistry & Materials Innovation Factory and School of Engineering
& Materials Innovation Factory, University
of Liverpool, Oxford Street, Liverpool L69 7ZD, U.K.
| | - Tom O. McDonald
- Department
of Chemistry & Materials Innovation Factory and School of Engineering
& Materials Innovation Factory, University
of Liverpool, Oxford Street, Liverpool L69 7ZD, U.K.
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2
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Dokkhan C, Mokhtar MZ, Chen Q, Saunders BR, Hodson NW, Hamilton B. Using microgels to control the morphology and optoelectronic properties of hybrid organic–inorganic perovskite films. Phys Chem Chem Phys 2018; 20:27959-27969. [DOI: 10.1039/c8cp05148h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Spin coating mixed microgel/perovskite precursor solutions gives disordered inverse opal perovskite films with morphologies and optoelectronic properties that are controlled by the microgel particles.
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Affiliation(s)
| | | | - Qian Chen
- School of Materials
- University of Manchester
- Manchester
- UK
| | | | - Nigel W. Hodson
- BioAFM Facility
- Faculty of Biology
- Medicine and Health
- Stopford Building
- University of Manchester
| | - Bruce Hamilton
- Photon Science Institute
- University of Manchester
- Alan Turing Building
- Manchester
- UK
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Chen M, Cui Z, Edmondson S, Hodson N, Zhou M, Yan J, O'Brien P, Saunders BR. Photoactive composite films prepared from mixtures of polystyrene microgel dispersions and poly(3-hexylthiophene) solutions. SOFT MATTER 2015; 11:8322-8332. [PMID: 26347070 DOI: 10.1039/c5sm01618e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Whilst polystyrene microgels belong to the oldest family of microgel particles, their behaviours when deposited onto substrates or prepared as composites have received little attention. Because polystyrene microgels are solvent-swellable, and inherently colloidally stable, they are well suited to form composites with conjugated polymers. Here, we investigate the morphology and light absorption properties of spin coated composite films prepared from mixed dispersions of polystyrene microgels and poly(3-hexylthiophene) (P3HT) for the first time. We compare the morphologies of the composite films to spin coated microgel films. The films were studied using optical microscopy, SEM, AFM, wide-angle X-ray diffraction and UV-visible spectroscopy. The films contained flattened microgel particles with an aspect ratio of ∼10. Microgel islands containing hexagonally close packed particles were evident for both the pure microgel and microgel/P3HT composite films. The latter were electrically conducting. The composite film morphology was dependent on the microgel and P3HT concentration used for film preparation and a morphology phase diagram was constructed. The P3HT phase acted as an electrically conducting cement and increased the robustness of the films to solvent washing. The composite films were photoactive due to the P3HT component. The absorbance for the films was tuneable and increased linearly with both microgel and P3HT concentration. The results of the study should apply to other organic swellable microgel/conjugated polymer combinations and may lead to new colloidal composites for future optoelectronic applications.
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Affiliation(s)
- Mu Chen
- Polymers Composites and Carbon Research Group, School of Materials, The University of Manchester, Grosvenor Street, Manchester, M13 9PL, UK.
| | - Zhengxing Cui
- Polymers Composites and Carbon Research Group, School of Materials, The University of Manchester, Grosvenor Street, Manchester, M13 9PL, UK.
| | - Steve Edmondson
- Polymers Composites and Carbon Research Group, School of Materials, The University of Manchester, Grosvenor Street, Manchester, M13 9PL, UK.
| | - Nigel Hodson
- BioAFM Facility, Stopford Building, The University of Manchester, Oxford Road, Manchester, M13 9PT, UK
| | - Mi Zhou
- Centre for Tissue Injury and Repair, Institute for Inflammation and Repair, Faculty of Medical and Human Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PT, UK
| | - Junfeng Yan
- Polymers Composites and Carbon Research Group, School of Materials, The University of Manchester, Grosvenor Street, Manchester, M13 9PL, UK.
| | - Paul O'Brien
- Polymers Composites and Carbon Research Group, School of Materials, The University of Manchester, Grosvenor Street, Manchester, M13 9PL, UK. and School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Brian R Saunders
- Polymers Composites and Carbon Research Group, School of Materials, The University of Manchester, Grosvenor Street, Manchester, M13 9PL, UK.
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5
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Platen M, Mathieu E, Lück S, Schubel R, Jordan R, Pautot S. Poly(2-oxazoline)-Based Microgel Particles for Neuronal Cell Culture. Biomacromolecules 2015; 16:1516-24. [DOI: 10.1021/bm501879h] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mitja Platen
- Center
for Regenerative Therapies Dresden, Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany
| | - Evelien Mathieu
- Center
for Regenerative Therapies Dresden, Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany
| | - Steffen Lück
- Professur
für Makromolekulare Chemie, Department Chemie, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
- Dresden Initiative for Bioactive Interfaces & Materials, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
| | - René Schubel
- Professur
für Makromolekulare Chemie, Department Chemie, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
- Dresden Initiative for Bioactive Interfaces & Materials, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
| | - Rainer Jordan
- Center
for Regenerative Therapies Dresden, Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany
- Professur
für Makromolekulare Chemie, Department Chemie, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
- Dresden Initiative for Bioactive Interfaces & Materials, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
| | - Sophie Pautot
- Center
for Regenerative Therapies Dresden, Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany
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Contreras-Cáceres R, Schellkopf L, Fernández-López C, Pastoriza-Santos I, Pérez-Juste J, Stamm M. Effect of the cross-linking density on the thermoresponsive behavior of hollow PNIPAM microgels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:1142-1149. [PMID: 25526382 DOI: 10.1021/la504176a] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report on the fabrication of thermally responsive hollow pNIPAM particles through the oxidation of the metal core in an Au@pNIPAM system. The selective oxidation of the Au core is achieved by addition of AuCl4(-) to an aqueous dispersion of Au@pNIPAM particles in the presence of cetyltrimethylammonium bromide (CTAB). We fabricate hollow pNIPAM particles with three cross-linking densities (N,N'-methylenebis(acrylamide), BA, at 5%, 10%, and 17.5%). The study of the effect of the amount of BA within the microgel network was performed by dynamic light scattering (DLS), transmission electron microscopy (TEM), and atomic force microscopy (AFM), showing its key role in determining the final hollow structure and thermal response. While the thermal responsiveness is largely achieved at low cross-linking densities, the hollow structure only remains at larger cross-linking densities. This was further confirmed by cryo-TEM analysis of hollow pNIPAM particles below and above the volume phase transition temperature (VPTT). Thus, it clearly shows (i) the shrinking of particle size with the temperature at low cross-linking density and (ii) the dependence of particle size on the amount of cross-linker for the final hollow pNIPAM structure. Observed differences in the hollow pNIPAM structure are attributed to different elastic contributions (Π(elas)), showing higher elasticity for microgels synthesized at lower amount of BA.
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Affiliation(s)
- Rafael Contreras-Cáceres
- Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Málaga , 29071 Málaga, Spain
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Thaiboonrod S, Cellesi F, Ulijn RV, Saunders BR. One-step preparation of uniform cane-ball shaped water-swellable microgels containing poly(N-vinyl formamide). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:5227-5236. [PMID: 22224722 DOI: 10.1021/la204606v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In this study we report the preparation of a new family of core-shell microgels that are water-swellable and have a morphology that is controllable by particle composition. Here, nearly monodisperse core-shell PNVF-xGMA [poly(N-vinylformamide-co-glycidyl methacrylate)] particles (where x is the weight fraction of GMA used) were prepared via nonaqueous dispersion (NAD) polymerization in one step. The shells were PGMA-rich and were cross-linked by reaction of epoxide groups (from GMA) with amide groups (from NVF). The core of the particles was PNVF-rich. A bifunctional cross-linking monomer was not required to prepare these new microgels. The particles had a remarkable "cane-ball"-like morphology with interconnected ridges, and this could be controlled by the value for x. The particle size was tunable over the range 0.8-1.8 μm. Alkaline hydrolysis was used to hydrolyze the PNVF segments to poly(vinylamine), PVAM. The high swelling pressure of the cationic cores caused shell fragmentation and release of some of the core polymer when the hydrolyzed particles were dispersed in pure water. The extent to which this occurred was controllable by x. Remarkably, the PGMA-rich shells could be detached from the hydrolyzed particles by dispersion in water followed by drying. The hydrolyzed PNVF-0.4GMA particles contained both positively and negatively charged regions and the dispersions appeared to exhibit charge-patch aggregation at low ionic strengths. The new cross-linking strategy used here to prepare the PNVF-xGMA particles should be generally applicable for amide-containing monomers and may enable the preparation of a range of new water-swellable microgels.
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Affiliation(s)
- Sineenat Thaiboonrod
- Biomaterials Research Group, Manchester Materials Science Centre, School of Materials, The University of Manchester, Manchester, United Kingdom
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8
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Fan K, Bradley M, Vincent B. Photo-responsive properties of poly(NIPAM-co-AAc) microgel particles with absorbed, hydrophobically modified organic salts. J Colloid Interface Sci 2012; 368:287-91. [DOI: 10.1016/j.jcis.2011.11.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 11/07/2011] [Accepted: 11/08/2011] [Indexed: 10/15/2022]
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9
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Muluneh M, Sprakel J, Wyss HM, Mattsson J, Weitz DA. Direct visualization of pH-dependent evolution of structure and dynamics in microgel suspensions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:505101. [PMID: 22040676 DOI: 10.1088/0953-8984/23/50/505101] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We use 3D confocal microscopy combined with image analysis and particle tracking techniques to study the structure and dynamics of aqueous suspensions of fluorescently labelled p(NIPAm-co-AAc) microgel particles. By adjusting the pH we can tune the interactions between the microgel particles from purely repulsive near neutral pH, to weakly attractive at low pH. This change in the interaction potential has a pronounced effect on the manner in which the suspensions solidify. We directly follow the evolution of the system after a quench from the liquid state to obtain detailed information on the route to kinetic arrest. At low pH and low concentration, dynamic arrest results mainly from crystallization driven by the attraction between particles; crystal nucleation occurs homogeneously throughout the sample and does not appear to be localized to geometric boundaries. Moreover, the growth of crystals is characterized by nucleation-limited kinetics where a rapid growth of crystal domains takes place after a long concentration-dependent lag time. At low pH and high concentration, relaxation of the suspension is constrained and it evolves only slightly, resulting in a disordered solid. At neutral pH, the dynamics are a function of the particle number concentration only; a high concentration leads to the formation of a disordered soft glassy solid.
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Affiliation(s)
- M Muluneh
- Department of Physics and School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
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10
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Lietor-Santos JJ, Gasser U, Vavrin R, Hu ZB, Fernandez-Nieves A. Structural changes of poly(N-isopropylacrylamide)-based microgels induced by hydrostatic pressure and temperature studied by small angle neutron scattering. J Chem Phys 2010; 133:034901. [DOI: 10.1063/1.3447386] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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11
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Choi JY, Lee K, Lee BH, Choe S. Effect of co-initiator on the size distribution of the stable poly(styrene-co-divinylbenzene) microspheres in acetone/water mixture. Macromol Res 2009. [DOI: 10.1007/bf03218896] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Eckert T, Richtering W. Thermodynamic and hydrodynamic interaction in concentrated microgel suspensions: Hard or soft sphere behavior? J Chem Phys 2008; 129:124902. [DOI: 10.1063/1.2978383] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Liu G, Yang X, Wang Y. Preparation of monodisperse hydrophilic polymer microspheres withN,N′-methylenediacrylamide as crosslinker by distillation precipitation polymerization. POLYM INT 2007. [DOI: 10.1002/pi.2223] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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14
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Pyett S, Richtering W. Structures and dynamics of thermosensitive microgel suspensions studied with three-dimensional cross-correlated light scattering. J Chem Phys 2005; 122:34709. [PMID: 15740219 DOI: 10.1063/1.1834492] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The structure factors, short- and long-time diffusion coefficients, and hydrodynamic interactions of concentrated poly(N-isopropylacryamide) microgel suspensions were measured with simultaneous static and dynamic three-dimensional cross-correlated light scattering. The data are interpreted through comparison to hard sphere theory. The structure factors are known to be described well by the hard sphere approximation. When the structure factor is fit to an effective hard sphere volume fraction and radius, the diffusion and hydrodynamic interactions are also well described by the hard sphere model. We demonstrate that one single hard sphere volume fraction is sufficient to describe the microgel structures, hydrodynamic interactions, and long- and short-time collective diffusion coefficients. This result is surprising because the particle form of the microgels at these temperatures is not rigid, but rather "fuzzy" spheres with dangling polymer chains.
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Affiliation(s)
- Stacy Pyett
- Lehrstuhl für Physikalische Chemie II, RWTH Aachen University, Templergraben 59, D-52056 Aachen, Germany.
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15
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Tan BH, Tam KC, Lam YC, Tan CB. Dynamics and microstructure of charged soft nano-colloidal particles. POLYMER 2004. [DOI: 10.1016/j.polymer.2004.05.055] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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16
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Chen X, Chen Z, Lu G, Bu W, Yang B. Measuring the swelling behavior of polymer microspheres with different cross-linking densities and the medium-dependent color changes of the resulting latex crystal films. J Colloid Interface Sci 2003; 264:266-70. [PMID: 12885544 DOI: 10.1016/s0021-9797(03)00485-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We measured the size changes of cross-linked polymer microspheres of narrow size distribution with different cross-linking densities by the in situ swelling method. The swelling behavior of these cross-linked polymer microspheres revealed that their maximal swelling degree linearly decreased as a function of the cross-linker content from 6.65 at 1.36 mol% to 2.43 at 3.25 mol%. By means of UV-vis spectra, we observed the spectral changes of the latex crystal films composed of these cross-linked polymer microspheres when we filled the interstices of the latex crystal films with different fluid media. Some succeeding peak shifts were observed, which may have resulted from the movement or the swelling of the polymer microspheres in the latex crystals.
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Affiliation(s)
- Xin Chen
- Key Laboratory of Supramolecular Structure and Materials, Department of Chemistry, Jilin University, Changchun 130023, People's Republic of China
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17
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Chen X, Cui Z, Chen Z, Zhang K, Lu G, Zhang G, Yang B. The synthesis and characterizations of monodisperse cross-linked polymer microspheres with carboxyl on the surface. POLYMER 2002. [DOI: 10.1016/s0032-3861(02)00262-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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18
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Varga I, Gilányi T, Mészáros R, Filipcsei G, Zrínyi M. Effect of Cross-Link Density on the Internal Structure of Poly(N-isopropylacrylamide) Microgels. J Phys Chem B 2001. [DOI: 10.1021/jp004600w] [Citation(s) in RCA: 213] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Imre Varga
- Department of Colloid Chemistry, Loránd Eötvös University, P.O. Box 32, H-1518 Budapest 112, Hungary, and Department of Physical Chemistry, Technical University of Budapest, H-1521 Budapest, Hungary
| | - Tibor Gilányi
- Department of Colloid Chemistry, Loránd Eötvös University, P.O. Box 32, H-1518 Budapest 112, Hungary, and Department of Physical Chemistry, Technical University of Budapest, H-1521 Budapest, Hungary
| | - Róbert Mészáros
- Department of Colloid Chemistry, Loránd Eötvös University, P.O. Box 32, H-1518 Budapest 112, Hungary, and Department of Physical Chemistry, Technical University of Budapest, H-1521 Budapest, Hungary
| | - Genoveva Filipcsei
- Department of Colloid Chemistry, Loránd Eötvös University, P.O. Box 32, H-1518 Budapest 112, Hungary, and Department of Physical Chemistry, Technical University of Budapest, H-1521 Budapest, Hungary
| | - Miklós Zrínyi
- Department of Colloid Chemistry, Loránd Eötvös University, P.O. Box 32, H-1518 Budapest 112, Hungary, and Department of Physical Chemistry, Technical University of Budapest, H-1521 Budapest, Hungary
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19
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Lu X, Hu Z, Gao J. Synthesis and Light Scattering Study of Hydroxypropyl Cellulose Microgels. Macromolecules 2000. [DOI: 10.1021/ma000776k] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xihua Lu
- Departments of Physics and Materials Science, University of North Texas, Denton, Texas 76203
| | - Zhibing Hu
- Departments of Physics and Materials Science, University of North Texas, Denton, Texas 76203
| | - Jun Gao
- Departments of Physics and Materials Science, University of North Texas, Denton, Texas 76203
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Dowding PJ, Vincent B, Williams E. Preparation and Swelling Properties of Poly(NIPAM) "Minigel" Particles Prepared by Inverse Suspension Polymerization. J Colloid Interface Sci 2000; 221:268-272. [PMID: 10631030 DOI: 10.1006/jcis.1999.6593] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The characterization of temperature- and pH-sensitive poly-N-isopropylacrylamide (poly-NIPAM) microgel particles, produced by surfactant-free emulsion polymerization, has been extensively reported. In the work described here poly(NIPAM) gel particles, cross-linked with N-N'-methylenebisacrylamide (BA), have been produced using inverse suspension polymerization. These particles have been termed "minigels" here since they are somewhat larger than conventional microgels. Results suggest that minigel particles are formed as a dilute suspension, within the aqueous dispersed (droplet) phase. The hydrodynamic diameter of the minigel particles produced in this work is </=2.5 µm, at 25 degrees C. The effects of temperature and pH changes, variation in cross-linker concentration, and incorporation of a charged comonomer (methacrylic acid, MAA) have been investigated. Both poly(NIPAM-BA) and poly(NIPAM-BA-MAA) minigel particles are temperature sensitive with swelling behavior consistent with comparable microgels. Variations in pH were found to effect the size of minigels containing ionizable groups (such as a carboxylate) by a mechanism of increased electrostatic repulsion of charged groups with increasing pH. Overall, the production of temperature- and/or pH-sensitive polymers by inverse suspension polymerization results in particles with swelling characteristics similar to those produced by emulsion polymerization, albeit with differing particle sizes. Copyright 2000 Academic Press.
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Affiliation(s)
- PJ Dowding
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, United Kingdom
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23
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Chen D, Doi M. Microstructure and Viscosity of Aggregating Colloids under Strong Shearing Force. J Colloid Interface Sci 1999; 212:286-292. [PMID: 10092357 DOI: 10.1006/jcis.1998.6011] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Disaggregation under strong shearing force is simulated for an aggregating colloid based on a sticky particle model which can describe the disaggregating and aggregating kinetics, the deformation, and the rupture of clusters with a minimum number of parameters. For a 2-dimensional system, the viscosity and coordination number of the model colloid are calculated at each time step, and the changes of microstructure with shear flow are observed directly by displaying the configuration of particles onto a monitor. The viscosity depends on both area fraction and shear rate, but coordination number depends only on shear rate. Furthermore, the viscosity and coordination number at steady state are independent of the initial state of particles, which indicates that the disaggregation and aggregation are mutually reversible. Copyright 1999 Academic Press.
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Affiliation(s)
- D Chen
- School of Graduate, China Textile University, Shanghai, 200051, China
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24
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Saunders BR, Vincent B. Microgel particles as model colloids: theory, properties and applications. Adv Colloid Interface Sci 1999. [DOI: 10.1016/s0001-8686(98)00071-2] [Citation(s) in RCA: 804] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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25
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Saunders BR, Vincent B. Osmotic deswelling of microgel particles in the presence of free polymer. ACTA ACUST UNITED AC 1997. [DOI: 10.1007/bf01188917] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Saunders BR, Crowther HM, Vincent B. Poly[(methyl methacrylate)-co-(methacrylic acid)] Microgel Particles: Swelling Control Using pH, Cononsolvency, and Osmotic Deswelling. Macromolecules 1997. [DOI: 10.1021/ma961277f] [Citation(s) in RCA: 169] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Brian R. Saunders
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
| | - Helen M. Crowther
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
| | - Brian Vincent
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
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Thickening of electrostatically stabilized latices by ethyl acrylate-methacrylic acid copolymers with various molecular weights. Colloids Surf A Physicochem Eng Asp 1996. [DOI: 10.1016/0927-7757(96)03634-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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