Poly(N-vinylcaprolactam) Microgel Particles Grafted with Amphiphilic Chains

Abstract

Grafted temperature-sensitive poly(N-vinylcaprolactam), PVCL, microgel particles have been prepared. The grafting has been accomplished using an amphiphilic macromonomer consisting of a hydrocarbon segment and a poly(ethylene oxide), PEO, segment. The water-soluble amphiphilic macromonomer has been synthesized and utilized in two different cases. In the first case, the grafted particles were prepared using macromonomers as reactive emulgators in emulsion copolymerization. In the second case the PVCL particles were first synthesized in an emulsion stabilized with SDS, and then, the microgel particles swollen with monomers were postmodified with amphiphilic macromonomers. Properties of the grafted nanoparticles in water were investigated by static and dynamic light scattering, as well as by 1H NMR relaxation and diffusion measurements. All the polymers show the LCST behavior typical to PVCL, and they collapse upon heating. For the particles prepared in one step in an emulsion stabilized by the macromonomer, the collapse was discontinuous and took place in a very narrow temperature range. When the particles were prepared in two steps, the grafts were observed to change the particle size as well as the critical temperature of the collapse. In the latter case the thermal transition was much more gradual than in the former one. This is probably due to a difference in the number of electric charges in the polymer particles, originating from the initiator and SDS.

Mesoporous silica particles grafted with poly(ethyleneoxide‐block‐N‐vinylcaprolactam)

“…Laukkanen et al observed different behavior of the PEO grafts on the PVCL microgel particles. 29 In that case, the diffusion coefficient of PEO increased above the LCST of PVCL because the gel particles were colloidally very stable and their diffusion rate increased upon the thermal collapse. In the case of inorganic solid silica particles, the situation is totally different.…”

“…27,28 An attracting thermo responsive polymer for biomedical applications is poly(N-vinylcaprolactam). Laukkanen et al 29 synthesized thermoresponsive PVCL microgel particles for controlled drug-delivery applications. Vihola et al 30 showed that the cytotoxicity of PVCL is low and it is well suitable for drug-release applications.…”

Microgels by Precipitation Polymerization: Synthesis, Characterization, and Functionalization

“…PVCL microgels with grafted amphiphilic chains were prepared by using reactive macromonomer consisting of a hydrophobic hydrocarbon segment and hydrophilic PEO segment [87]. Due to the amphiphilic character of the macromonomer and its ability to form micelles in water (CMC value was 0.25 g L −1 at 20 • C), the obtained microgels exhibited a small size (73 nm at 20 • C) and narrow size distribution.…”

A Novel Method to Prepare 5-Fluorouracil, an Anti-cancer Drug, Loaded Microspheres from Poly(N-vinyl caprolactam-co-acrylamide) and Controlled Release Studies

“…After co-polymerization [5,6], the latex solution was added to 1% calcium chloride solution and centrifuged to isolate particles from the mixture. The microspheres were washed The correlation coefficients (r) were calculated by least-squares method at 95% confidence limit.…”

“…The release of active agents from biodegradable polymers has many advantages over synthetic polymers because they can be easily degraded in the body and provide the desired therapeutic effect. Such CR systems have many advantages over the conventional dosage forms, including improved efficacy/patient compliance, reduced toxicity and convenience [4][5][6]. Among the various types of polymers employed in pharmaceutical applications, hydrophilic bio-polymers, such as sodium alginate, chitosan, etc.…”