Redox-triggered crosslinking of a degradable polymer

Abstract

A unique redox-triggered crosslinking reaction is disclosed that capitalizes on the orthogonal reactivity of an iron-based catalyst for the ring opening polymerization of cyclic diesters and epoxides.

Functional biodegradable polymers via ring-opening polymerization of monomers without protective groups

“…Starting from an appropriate alkyl bromide (e.g. propargyl bromide), a Barbiertype addition to glyoxylic acid/ester (and cleavage of the ester, if used) resulted in a glycolic acid derivative which further reacted with 2-bromoacetyl bromide (or 2-bromopropanoyl bromide in case of a lactide monomer 129,[133][134][135] ). Intramolecular cyclization in diluted solution yielded the monomer (yields typically 15-45%).…”

“…The monomer was also further functionalized by olefin cross-metathesis with an epoxy alkene and further hydrogenated to the saturated epoxy lactide (A53). 134 An orthogonal reactive iron-based catalyst was applied for the polymerization of A53, which selectively polymerizes the diester cycle if the catalyst is in the iron(II) form. The oxidized catalyst (iron(III)-species) instead selectively polymerizes the epoxide.…”

Reversible redox controlled acids for cationic ring-opening polymerization

“…[1][2][3] While living polymerization methodologies in conjunction with carefully chosen and timed monomer additions produce well-defined materials (e.g., block copolymers 2 ), the ability to control chain growth with an external stimulus could lead to many advanced structures and architectures with potentially interesting physical properties. These externally controlled polymerization methodologies rely on changes in chemical reactivity upon application of an external stimulus (chemical, [4][5][6][7][8][9][10][11][12][13][14][15][16][17] electrochemical, [18][19][20] photochemical, [21][22][23][24][25][26][27][28][29][30] thermal, [31][32][33] mechanochemical [34][35][36][37] ), which precisely regulates the incorporation of monomers at a growing polymer chain end. In addition to promoting the synthesis of advanced structures and architectures, 30,45 the spatiotemporal control afforded by these externally controlled polymerizations has enabled the development of new lithographic [38][39][40][41]<...>…”

Modulating Polymer Dispersity with Light: Cationic Polymerization of Vinyl Ethers Using Photochromic Initiators

“…Thedevelopment of polymerization processes that can be controlled by external stimuli, [1] including light, [2] redox, [3] and mechanical force, [4] among others,i savigorously growing field of study.T he enhanced control offered by these systems has the potential to enable access to complex polymer structures that are difficult to obtain using traditional methods.W hile developments in this area have mainly focused on regulating overall polymerization rate [1c, 2a,b, 3b,5] or selectivity for individual monomers in am ixed monomer pool, [6] thee merging exploration of externally regulating other aspects of polymerization reactions such as crosslinking, [7] branching, [8] and molecular-weight distribution (MWD), [8c,9] is an exciting prospect. In particular, manipulating various aspects of polymer MWD,i ncluding skew and breadth (e.g.d ispersity), are promising avenues for tuning apolymersprocessability,physical and material properties, [10] as well as the self-assembly properties of block copolymers,all without altering the polymersmolecular structure.…”