Core–shell nanogels by RAFT crosslinking polymerization: Synthesis and characterization

Abstract

A synthetic methodology is described for the preparation of core-shell nanogels by reversible addition-fragmentation chain transfer. Well-defined macro chain transfer agents (macro-CTA's) were prepared in a first step using monomers that yield sensitive polymers. In the second step, a crosslinker alone or with the addition of a functionalized comonomer were used to form a crosslinked core. The ratio of crosslinker to macro-CTA is crucial to yield nanogels. Furthermore, the polymerization time has an impact in the architecture of the nanomaterial obtained: it evolves from a core-crosslinked star to a core-shell nanogel. Controlling the molecular weight of the macro-CTA and the type of comonomer in the core forming step, core-shell nanogels with hydrodynamic diameters from 22 to 168 nm and a core that represents from 35 to 77% of the size, were prepared containing functional groups in the core which could be used as catalytic scaffolds. V C 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 4277-4287, 2012.

PNVCL‐PEGMA nanohydrogels with tailored transition temperature for controlled delivery of 5‐fluorouracil

“…ρ ‐values are within the range 0.98–1.53. Values close to 0.98, 1.3, and 1.53 are associated with morphology of “soft sphere,” regular stars (uniform arm length) and regular stars (polydisperse arms), respectively . Calculated ρ ‐values suggest that core‐shell nanogels of flexible chains were obtained .…”

“…The Berry plot for sample N45‐2MBA12, measured in water at 25 °C (Fig. ), showed linear dependence on the scattering angle, and was related to homogeneous particles (see additional Berry plots in Supporting Information) . Table summarizes the data of M w , R g , and A 2 for six samples.…”

“…2), showed linear dependence on the scattering angle, and was related to homogeneous particles (see additional Berry plots in Supporting Information). 37,38 Table 1 summarizes the data of M w , R g , and A 2 for six samples. Nanohydrogels show high M w in the range from 4.67 3 10 7 to 2.64 3 10 9 g mol 21 and large R g between 98 and 150 nm.…”

“…stars (uniform arm length) and regular stars (polydisperse arms), respectively. 35,38 Calculated q-values suggest that core-shell nanogels of flexible chains were obtained. 37 Sample N32 (PNVCL-PEGMA) has the more compact structure.…”

Different Strategies for the Preparation of Galactose-Functionalized Thermo-Responsive Nanogels with Potential as Smart Drug Delivery Systems

“…Molecular weight (M w ), radius of gyration (R g ) and the second virial coefficient (A 2 ) data, were determined by static light scattering (SLS). The Berry plot for sample N45, measured in water at 25 °C ( Figure 3 ), showed a linear dependence on the scattering angle, and was related to homogeneous particles [ 50 , 51 ]. Data from SLS and DLS are summarized in Table 1 ( Figures S3–S9 in SM ).…”