Rapid photochromic nanopatterns from block copolymers

Abstract

Photochromic nanopatterns were produced from the self-assembly of poly(methyl methacrylate)-bpoly(n-butylacrylate) (PMMA-b-PBA) block copolymers incorporating a naphthopyran photochromic dye. The PMMA-b-PBA block copolymers were synthesized by reversible addition fragmentation chain transfer polymerization with a photochromic dye (9-acryloyloxy-[3,3-bis(4-methoxyphenyl)]-3Hnaphtho[2,1-b]pyran) attached to the PBA block (PMMA-b-P(BA-co-NA)). The very low glass transition temperature of the poly(n-butyl acrylate) (PBA) block allows for rapid decolouration of the naphthopyran dye, whilst the PMMA matrix permits the macroscopic rigidity of the photochromic film to be maintained. The resulting films exhibit the fastest rate of colour switching reported to date for a naphthopyran polymeric film. Furthermore, the PMMA-b-PBA block copolymer exhibits microphase separation in nanodomains of controlled and regular morphology, thus allowing the confinement of the photochromic dye in well-controlled nanostructures. This feature allowed us to design polymeric films exhibiting precisely defined photochromic nanopatterns.

Living Radical Polymerization by the RAFT Process – A Third Update

“…A study on the use of benzyl and t-butyl trithiocarbonate and dithiobenzoate RAFT agents for VAc polymerization has 334 [385] 335 [540] 336 [429] 337 [202] 338 [242] 339 [262] 340 [317] Solketal acrylate 350 [311] 347 [344] 346 [344] 343 n ϭ 1 [234] 343 n ϭ 2 [196] 345 n ϭ 4 [362] 351 [297] 342 [196] 341 [428] 348 [311] 349 [311] 394 [396] Chart 3.…”

“…[267] Pressley et al [611] have reported on an improved methodology for conducting click reactions to form block and cyclic polymers. [227] PFPMA/LMA Ph AIBN 25 70 100 [225] BA Ph AIBN 30 80 ,25 [194] HA Ph ACPA 5 70 100 [240] HA Ph AHPN 5 70 100 [240] BA/NA Ph AIBN 20 80 100 [202] BA C 4 H 9 S AIBN 30 80 ,25 [194] BA C 4 H 9 S AIBN þ BPO 20 þ 2 E 80 100 [194] HPA [596] tBA Poly(tBA)S AIBN -80 100 [597] NIPAm Poly(tBA-b-NIPAm)S AIBN -80 100 [597] tBA/TBBPMA Ph AIBN (20) (80) 100 [598] DAMEA/TFEA C 12 H 25 S AIBN 20 65 100 [599] HADA [194] St Ph AIBN þ BPO 20 þ 2 E 80 100 [194] St C 4 H 9 S AIBN 30 À 100 80 ,60 [194] St C 12 H 25 S AIBN 10 95 92 [393] A Monomer unit adjacent to thiocarbonylthio group. The process makes use of commercially available copper nanoparticles and is performed with microwave irradiation.…”

Photochromic behavior of naphthopyran in styrene–butadiene–styrene elastomer thin films: Effect of stretching of film and linker

“…Suggesting the structures of naphthopyran‐grafted SBS elastomers as shown in Scheme , it was assumed that a radical transfer to the methylene group of the PB block initiated the graft polymerization 23–25. In 1 H‐NMR spectra of grafted elastomers, the hydrogen peak at about 6.2, attributed to the double bond of pyran ring were observed, which also indicates that the naphthopyran monomer were grafted onto the SBS polymer chains 26, 27. All purified samples were collected and dried under vacuum conditions.…”

The use of poly(alkylene oxide)s to achieve fast and controlled photochromic switching in rigid matrices

“…Other work in this area has also demonstrated enhanced switching performance in rigid matrices through conjugates synthesized via the copolymerization of (meth)acrylate functionalized photochromic dye monomers with n ‐butyl acrylate 8. Similarly, fast switching has been achieved in thin polymer films by the copolymerization of naphthopyran monomers into the soft nanodomains of AB block copolymers having phase‐separated soft and hard segments 14…”