Microgel temperature-responsive

Tungchaiwattana, S., Liu, R., Kalacheva, S., Shahidan, N.N., Kells, A., Saunders, B.R., 2013. Mixmres of pH-responsive microgels and temperature-responsive star-like copolymers from heteroaggregation to gelation. Soft Matter 9, 35—47. 

Hoare, T. and R. Pelton (2004). Highly pH and temperature responsive microgels functionalized with vinylacetic acid. Macromolecules 37(7) 2544-2550. 

Acciaro R, Aulin C, Waghtig L et al (2011) Investigation of the formation, structure and release characteristics of self-assembled composite films of cellulose nanofibrils and temperature responsive microgels. Soft MattCT 7 1369-1377... 

Hollow silica gels were prepared using PNlPAAm by Liu et al. Rhodamine B was taken as the model drug, it was observed that the LCST of the PNlPAAm was increased to 40.6°C, which indicates a good performance of temperature-dependent phase transition. To further confirm the temperature responsiveness of the system, the release study was carried out at 25°C and 40°C. it was observed that 82.5% of the RHB was released for 12 h at 25°C while 86.5% was released at 40°C in 12 h. Thus, this indicates the prepared microgels achieve thermoresponsive controlled release behavior and were also found to be biocompatible [36]. Some of the applications of thermoresponsive polymers in drug delivery are summarised in Table 20.1. 

A new synthetic protocol for the synthesis of large diameter (2.5-5pm), temperature-, and pH-responsive microgels via aqueous surfactant-free radical... 

The implication of such stimuli-responsive particles as a solid polymer support of biomolecules in the biomedical field is probably due to various factors (1) easiest to prepare via precipitation polymerization (hydrogel particles) or a combination of emulsion and precipitation polymerizations (core-shell particles), (2) the colloidal properties are related to the temperature and to the medium composition (i.e., pH, salinity, surfactant etc.), (3) the adsorption and the desorption of antibodies and proteins are principally related to the incubation temperature, (4) the covalent binding of proteins onto such hydrophilic and stimuli-responsive particles can be controlled easily by temperature, and, finally, (5) the hydrophilic character of the microgel particles is an undeniably suitable environment for immobilized biomolecules. 

Since Pelton and Chibante reported the synthesis of the first temperature-sensitive microgel from iV-isopropylacrylamide (NIPAM) and crosslinker in 1986 [74], responsive microgels have attracted numerous attempts to explore their potential application in many fields, such as sensing and drug delivery [75]. Now the most extensively studied respruisive microgels are prepared with poly(fV-isopropyla-crylamide) (PNIPAM) [2], It is weU known that the phase transition temperature of PNIPAM is about 32°C [76], When r< LCST, the PNIPAM chain is soluble in water as a random cod. When r LCST, the subtle balance between PNIPAM and water is broken and phase transition occurs [77]. However, the single-molecule level mechanism of the phase transition of PNIPAM had not been proposed until very recently. 

Debord, J. D. and L. A. Lyon (2003). Synthesis and characterization of pH-responsive copolymer microgels with tunable volume phase transition temperatures. Langmuir 19(18) 7662-7664. 

In previous work reported on PDMAEMA-based microgels, most of them are prepared using At//-dimethylaminoethyl methaciylate (DMAEMA) as the monomer, and with one or two other comonomers added in the preparation process. " Although these copolymerizations are reported to enhance the glass transition temperature (Tg) or generate multi-stimuli-responsive properties, the pH sensitivity of the prepared microgels is reduced to a certain extent in most cases. To overcome this problem, PDMAEMA... 

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