Self‐assembly and degradation of poly[(2‐methacryloyloxyethyl phosphorylcholine)‐block‐(D,L‐lactide)] diblock copolymers: large compound micelles to vesicles

Abstract

Biodegradable poly[(2‐methacryloyloxyethyl phosphorylcholine)‐block‐(D,L‐lactide)] (PMPC‐b‐PLA) diblock copolymers with various hydrophilic PMPC weight fractions (fPC) will spontaneously self‐assemble into well‐defined vesicles and large compound micelles (LCMs) in water. Transmission electron microscopy, scanning electron microscopy, dynamic light scattering and fluorescence microscopy were used to observe their aggregate morphologies. The degradation of the LCMs was investigated and the loss of molecular weight of PLA blocks was confirmed using 1H NMR analysis. The hydrolysis of PLA increases fPC and consequently shifts the preferred morphology from LCMs to vesicles. Such degradation‐induced morphological transitions mean that the biocompatible and biodegradable LCMs have great application potential in drug delivery. Copyright © 2010 Society of Chemical Industry

Effects of Chemical Modifications on the Thermoresponsive Behavior of a PDMAEA-b-PNIPAM-b-POEGA Triblock Terpolymer

“…The R g /R ho ratio values can give significant details about the morphology/structure of the formed nanostructures. As it is reported in the literature, the corresponding R g /R ho ratio values for spherical micellar structures (core-shell morphology) are in the range of 0.7-0.9, and for vesicular structures, they are in the range of 0.9-1.9 [70]. Therefore, the formed nanosized particles are expected to have spherical structures in the cases that the determined R g /R ho ratio values are close to 0.8 and maybe vesicular structures in the cases that the determined R g /R ho ratio values are above 0.9.…”

Stimuli‐responsive amphiphilic PDMAEMA‐b‐PLMA copolymers and their cationic and zwitterionic analogs

“…Additionally, in Table , the length of the extended single copolymer chains is listed, which is apparently smaller than the determined size of PDMAEMA‐ b ‐PLMA aggregates (Table ). This fact indicates the existence of spherical supramolecular micellar aggregates, having not a simple core–shell structure but rather a compound micelle morphology . In previous work where amphiphilic block copolymers based on PLMA block were studied we reported the formation of compound micelles in aqueous solutions, due to the long aliphatic side chains of PLMA, which make difficult the organization of the PLMA blocks in small spherical cores .…”

Synthesis and self‐assembly of thermoresponsive poly(N‐isopropylacrylamide)‐b‐poly(oligo ethylene glycol methyl ether acrylate) double hydrophilic block copolymers

“…These structures are expected to have a core–shell morphology since as temperature increases PNIPAM blocks become less hydrophilic and should occupy the inner part of the spherical structure/aggregate while the well solvated POEGA blocks should occupy the periphery. From the literature, R g / R h0 values in the range of 0.7–0.9 indicate spherical morphology and R g / R h values in the range of 0.9–1.9 indicate vesicular morphology …”

“…This observation indicates the hydrogen bonding between the carboxyl group of IND and amide group of PNIPAM block. Moreover, it is worth mentioning that in the spectrum of PNIPAM‐ b ‐POEGA‐2, the band at 1638 cm −1 was assigned to the carbonyl of amide group . It can be observed that in the spectra of copolymer/IND mixed aggregates, there is a small shift of the band attributed to the carbonyl group of amide group, most probably because of the intermolecular hydrogen bonding interactions between the carbonyl group of PNIPAM block and the hydroxyl group of IND.…”