Herein we report the first example of the controlled synthesis of linear and hyperbranched copolymers of 2-methylene-1,3-dioxepane (MDO) with functional vinyl monomers to deliver a range of functional, degradable polymers by reversible deactivation radical polymerization. The copolymerization was able to be tuned to vary the incorporation of degradable segments to create degradable materials with predictable molar mass, low dispersity values while also featuring side-chain functionality. The formation of nanoparticles by the addition of divinyladipate to form degradable hyperbranched copolymers was proven by DLS and TEM analyses.
The synthesis of vinyl bromobutanoate
(VBr), a new vinyl acetate
monomer derivative obtained by the palladium-catalyzed vinyl exchange
reaction between vinyl acetate (VAc) and 4-bromobutyric acid is reported.
The homopolymerization of this new monomer using the RAFT/MADIX polymerization
technique leads to the formation of novel well-defined and controlled
polymers containing pendent bromine functional groups able to be modified
via postpolymerization modification. Furthermore, the copolymerization
of vinyl bromobutanoate with 2-methylene-1,3-dioxepane (MDO) was also
performed to deliver a range of novel functional degradable copolymers,
poly(MDO-co-VBr). The copolymer composition was shown
to be able to be tuned to vary the amount of ester repeat units in
the polymer backbone, and hence determine the degradability, while
maintaining a control of the final copolymers’ molar masses.
The addition of functionalities via simple postpolymerization modifications
such as azidation and the 1,3-dipolar cycloaddition of a PEG alkyne
to an azide is also reported and proven by 1H NMR spectroscopy,
FTIR spectroscopy, and SEC analyses. These studies enable the formation
of a novel class of hydrophilic functional degradable copolymers using
versatile radical polymerization methods.
The copolymerization of vinyl acetate (VAc) and 2-methylene-1,3-dioxepane (MDO), as well as the homopolymerization of MDO in the presence of a p-methoxyphenyl xanthate chain transfer agent (CTA) is reported and comparison of the homopolymerization of MDO with other known xanthates was also investigated.
Polymers with a thermally triggered phase transition are important in the design of materials for biological applications, where their behavior can be used to trigger release or (dis)assembly events. Despite their advantages, a system with tunable thermal response, end-group reactive sites, low toxicity, and controlled main-chain degradability has not been realized, yet this would be a significant advance. The versatile new poly(oligo(ethylene glycol) vinyl acetate)s are presented with excellent control over their molecular properties obtained through RAFT/MADIX polymerization. Furthermore, we demonstrate structure-controlled thermal transitions, conjugation to human lysozyme through the retained end-group, and moreover show that this class of polymers can uniquely be copolymerized with 2-methylene-1,3-dioxepane (MDO) to generate polymers in which the degradability and cloud point can be independently tuned to create materials that display the same cloud point but degrade differently.
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