Association behavior of thermo-responsive block copolymers based on poly(vinyl ethers)

Abstract

Thermo-sensitive nanosized structures have been prepared in water from poly(methyl vinyl ether)-blockpoly(isobutyl vinyl ether) (PMVE-b-PIBVE) block copolymers. The composition and the architecture (diblock and triblock architectures) of the PMVE-b-PIBVE copolymers have been varied. The investigated copolymers had an asymmetric composition with a major PMVE block. While the PIBVE blocks are hydrophobic, the PMVE blocks are hydrophilic at room temperature and become hydrophobic above their demixing temperature (around 36 °C) as a result of the lower critical solution temperature (LCST) behavior. At room temperature, the amphiphilic copolymers aggregate in water above a critical micelle concentration, which has been experimentally measured by hydrophobic dye solubilization. The hydrodynamic diameter of the structures formed above the cmc has been measured by dynamic light scattering (DLS) while their morphology has been studied by transmission electron microscopy (TEM). 1 H NMR measurements in D 2 O at room temperature reveal that the aggregates contain PIBVE insoluble regions surrounded by solvated PMVE chains. These investigations have shown that polydisperse spherical micelles are formed for asymmetric PMVE-b-PIBVE copolymers containing at least 9 IBVE units. For copolymers containing less IBVE units, loose aggregates are formed.Finally, the thermo-responsive, reversible properties of these structures have been investigated. Above the cloud point of the copolymers, the loose aggregates precipitate while the micelles form large spherical structures.

Integrating Display and Delivery Functionality with a Cell Penetrating Peptide Mimic as a Scaffold for Intracellular Multivalent Multitargeting

“…Support for this assumption came from several observations, including a characteristic triazole peak in the 1 H NMR (Figure S6). The acridine resonances were not observed possibly because packing of the hydrophobic chromophores within the helix leads to their reduced mobility (slow tumbling) and poor solvation. , The ligand incorporation into the polymers was established by the acridine fluorescence observed for each polymer, and particularly by UV studies that showed an approximately linear increase in absorbance with L/G feed ratio (Figure S3). The molecular weight of each polymer 4 was calculated based on the molecular weight of parent PCPLGs determined by multiangle laser light scattering (MALLS) and the alkyne loading stoichiometry (Table S1).…”

Synthesis, characterization, and performance of a novel polycarboxylate superplasticizer with a crosslinked topological structure

“…This is possibly attributed to the higher adsorption amounts of TPC on the surfaces of cement particles. More calcium chelated complexes and more remarkable inhibition of hydration for TPC, thus resulting in the retardation of cement hydration …”

“…More calcium chelated complexes and more remarkable inhibition of hydration for TPC, thus resulting in the retardation of cement hydration. 36,37…”

Zugang zu metallorganischen Arylcobaltcorrinen durch radikalische Synthese: 4‐Ethylphenylcobalamin, ein potenzielles “Antivitamin B12”

“…Most of the studies of temperature‐responsive polymers focus on poly( N ‐alkylacrylamide)s, poly( N ‐vinylcaprolactam) and poly(vinyl methyl ether) and their derivatives since these polymers have the peculiarity of possessing a LCST in the physiological range, which is notably important for biomedical or clothing applications. It is possible to create temperature‐responsive systems based on these polymers in the form of micelles,2–6 nanoparticles,7–9 microparticles,10–13 capsules,14–16 hydrogels,17–19 interpenetrating networks,20, 21 films and coatings22–28 and fibres 29, 30. The temperature‐responsive systems based on coatings are commercially very interesting since they require a relatively small amount of the expensive temperature‐responsive polymer to provide a significant effect.…”