Functionalization of Reactive Polymeric Coatings via Diels–Alder Reaction Using Microcontact Printing

Abstract

The fabrication of polymeric thin fi lms amenable to facile functionalization by reactive μ CP via a Diels-Alder reaction is described. Precursor copolymers containing FuMA, PEGMA, and TMSMA are prepared using ATRP. Surface-tethered thin fi lms of these polymers are obtained on oxidized silicon and glass substrates and patterned with maleimide-appended dye molecules by simple μ CP to demonstrate effi cient functionalization via Diels-Alder reaction. Printing of biotin-based ligands is carried out to demonstrate directed immobilization of the enzyme streptavidin. Due to the thermoreversible nature of the Diels-Alder reaction, these surfaces can be used as rewritable platforms. This is demonstrated by sequential write-erase-rewrite protocols via μ CP of a maleimide-containing fl uorescent dye.reactions have been utilized to date toward effi cient functionalization of appropriately modifi ed solid substrates. The Cu-catalyzed Huisgen [3 + 2] reaction is perhaps the most utilized one, but other "click" reactions such as the thiol-ene and Diels-Alder reactions are drawing attention due to their metal-free nature. Among the later reactions, the Diels-Alder reaction provides an attractive alternative due to the following attributes: (1) appropriate choice of diene and dienophile provides products in good yields in a highly predictable manner, (2) the reaction could be conducted in aqueous medium or neat without harsh chemical conditions, (3) most often no additional reagents or catalysts are required, and (4) reaction is thermoreversible. [ 3 ] As mentioned in the last point, this conjugationdeconjugation reaction harbors several reaction systems which could be irreversible or reversible over different temperature ranges based upon the molecular structure of the diene-dienophile pair. [ 4 ] Specifi cally, the maleimidefuran-based systems have attracted immense attention because of the "self-healing" feature that allows the fabrication of remendable materials. [ 5 ] To date, most of the efforts in the area of surface functionalization using the Diels-Alder reaction have focused on the modifi cation of self-assembled monolayers on

Thermally reversible cross-linked poly(ether-urethane)s

“…The DA cycloaddition of furan and maleimide can be accomplished at or slightly above room temperature, while the rDA reaction is performed at elevated temperatures. Thermally rDA reactions have been used in numerous studies including polymer synthesis [10][11][12][13][14][15][16][17], dendrimers [18][19][20][21], epoxy resins [22][23][24][25], crosslinked polymer networks [26][27][28][29][30], organic-inorganic polymer hybrids [31][32][33], surfactants [34], surface modification [35,36] and remendable selfhealing polymers [37]. Due to the fact that these reactions can proceed under mild conditions without a catalyst, they are attractive for designing covalently reversible bonds with furan and maleimide functional groups which are responsible for association and disassociation [35,37,38].…”

Interfacial Thermoreversible Chemistry on Functional Coatings: A Focus on the Diels–Alder Reaction

“…to fabricate rewritable surfaces. Furan‐functionalized polymers were grafted on oxidized silicon and glass substrates and patterned by microcontact‐printing with maleimide‐terminated dye molecules or biotin ligands . Sun and co‐workers also reported the one‐step or two‐step immobilization of biomolecules onto glass slides at room temperature facilitated by an aqueous DA reaction.…”

Metal‐Free Click Chemistry Reactions on Surfaces

“…With surface patterning by simple μCP of maleimide‐containing dye molecules (boron‐dipyrromethene, BODIPY), they were able to immobilize FITC‐labeled streptavidin on biotin‐maleimide patterns. Next, they showed the rewritable properties of this ligation by five write‐and‐erase cycles, using this reversible DA reaction (125 °C, 2 h) …”

“…Schematic illustration of the reversible patterning of a maleimide‐containing BODIPY dye on reactive polymeric thin films by μCP …”