In Situ Observation of Dithiocarbamate-Based Surface Photograft Copolymerization Using Quartz Crystal Microbalance

Abstract

A quartz crystal microbalance (QCM) technique which can detect weight increase in the nanogram order has been employed to continuously monitor the iniferter-based surface photograft polymerization behavior of vinyl monomers. The gold electrodes of the QCM were thinly coated with a photoreactive polystyrene partially derivatized with N,N-diethyldithiocarbamylmethyl groups acting as iniferters. A monotonic decrease in the resonance frequency of the vibrating oscillator of QCM, which was correlated with the weight increase via graft copolymerization initiated on the polystyrene, occurred immediately after ultraviolet light irradiation of the coated electrode surface in a methanolic or aqueous solution of vinyl monomers such as acrylamide (AAm), N,N-dimethylacrylamide (DMAAm), methacrylamide (MAm), methacrylic acid (MA), ethyl acrylate (EA), 2-hydroxyethyl methacrylate (HEMA), 2-(dimethylamino)ethyl methacrylate (DMAEM), N-vinyl-2-pyrrolidone (VP), and styrene (ST), except for vinyl acetate (VA). Upon cessation of irradiation, little frequency change was observed. The cycle comprising a decrease in resonance frequency under irradiation and no change under dark condition was repeated without appreciable fatigue. The polymer yield showed an almost linear increase with irradiation time up to 20 min. The apparent polymerization rate increased with concentration of monomer, light intensity, and surface density of dithiocarbamate groups. In addition, the rate was dependent on monomer's Q value and maximum at Q values of around 0.7−0.8 for EMA and HEMA.

Swelling Behavior of Multiresponsive Poly(methacrylic acid)‐block‐‐poly(N‐isopropylacrylamide) Brushes Synthesized Using Surface‐Initiated Photoiniferter‐Mediated Photopolymerization

“…While SI-PMP is a robust method for growing polymer brushes and photoiniferter-mediated photopolymerization is, in general, known to be compatible for polymerization of wide array of monomers, including styrenic, acrylate, acrylamides and acidic monomers, [33,[45][46][47] care must be exercised to establish conditions that preserve the ability to reinitiate growth. Previously we showed that preaddition of TED, which undergoes homolytic cleavage to provide a source of deactivating, dithiocarbamyl radicals, to the reaction mixture enables formation of block copolymers by SI-PMP.…”

“Living” Free Radical Photopolymerization Initiated from Surface-Grafted Iniferter Monolayers

“…Kobayashi and co-workers 19 grafted N,N-(diethylamino)-dithiocarbamoylpropyl(trimethoxy)silane on a glass surface and initiated the photopolymerization of sodium styrenesulfonate from the surface, but a controlled radical polymerization could not be obtained, which corresponds to results found in the literature. 20 Nakayama, Matsuda, and co-workers used thin polymeric films partially derivatized with N,N-diethyldithiocarbamate groups and characterized the different grafted polymer layers with scanning force microscopy (SFM); 21 in this case the growing polymer chain is not directly bound to the (inorganic) substrate. The authors were able to obtain a patterned surface by applying a striped projection mask, which is an advantage of photopolymerizations.…”

Hg(II) removal with polyacrylamide grafted crosslinked poly(vinyl chloride) beads via surface‐initiated controlled/“living” radical polymerization

“…In DEDTC‐PVC, the photolysis of the N , N ‐diethyldithiocarbamate group can be seen in the form of macromolecular carbon radical (PVĊ with higher initiating activity and the small molecular sulfur radical (˙SC(S)NEt 2 ) with lower initiating activity. And then the macromolecular carbon radical initiated the radical polymerization of acrylamide; the Et 2 NSCṠ radical mainly reacted with growing radicals RM n ˙ to form dormant covalent species, which can again photochemically dissociate 33–36…”