The precise synthesis of polymers derived from alkyl lactate ester acrylates is reported for the first time.Kinetic experiments were conducted to demonstrate that Cu(0) wire-catalyzed single electron transferliving radical polymerization (SET-LRP) in alcohols at 25 ºC provides a green methodology for the LRP of this forgotten class of bio-based monomers. The acrylic derivative of ethyl lactate (EL) solvent and homologous structures with methyl and n-butyl ester were polymerized with excellent control over molecular weight, molecular weight distribution, and chain end functionality. Kinetics plots in conventional alcohols such as ethanol and methanol were first order in monomer with molecular weight increasing linearly with conversion. However, aqueous EL mixtures were found to be more suitable than pure EL to mediate the SET-LRP process. The near quantitative monomer conversion and high bromine chain-end functionality, demonstrated by MALDI-TOF analysis, further allowed the preparation of innovative bio-based block copolymers containing rubbery poly(ELA) sequences. For instance, poly(ELA-b-poly(glycerol acrylate) block copolymer self-assembled in water to form stable micelles with chiral lactic acid-derived block forming micellar core as confirmed by pyrene-probe-based fluorescence technique. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements revealed nanosize spherical morphology for these bio-based aggregates.
We report a new strategy toward the development of block
copolymer
surfactants from chemicals of the lactic acid family. A particularly
unique aspect of this work is the use of green solvents as biobased
platform chemicals to generate well-defined and nanostructure-forming
materials. Herein, efficient functionalization of ethyl lactate (EL)
and N,N-dimethyl lactamide (DML)
solvents with acrylate groups generated monomers that could be polymerized
by the photoinduced copper-catalyzed living radical polymerization
process to yield polymeric materials with different water solubilities.
These lactic acid-derived monomers were used as a major component
in well-defined diblock copolymers composed of poly(EL acrylate) and
poly(DML acrylate) segments as hydrophobic and hydrophilic building
blocks, respectively. The resulting amphiphilic copolymers could self-assemble
in aqueous solution to form nanoparticles with different morphologies
(e.g., large-compound micelles and vesicles). Subsequently, the formed
amphiphilic polymers were employed as efficient stabilizers in the
emulsion polymerization of methyl methacrylate and styrene, offering
a facile method for the synthesis of well-defined and stable polymer
latexes in the range of 100–200 nm, demonstrating the practical
significance of these biobased polymers in nanomaterial synthesis.
To be fully recyclable, covalent adaptable networks must ultimately be able to overcome all topological restrictions and flow. By using a statistically based method, it was shown that the extent of stress relaxation in disulfide-containing thiol−ene polymers is closely correlated to the fraction of permanent cross-links. Given sufficient disulfide content, the cured materials can be recycled at moderate temperatures with no apparent loss in tensile properties. Since the materials also feature ester bonds, even when the disulfide content is low, one can increase the reprocessing temperature to trigger transesterification reactions which ensure full stress relaxation and recyclability.
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