Synthesis of Block Copolymers Containing a Main Chain Polymeric NLO Segment

Abstract

A novel poly-4-vinylpyridine-b-PNLO (nonlinear optical material)-b-polystyrene-b-poly(4vinylphenol) tetrablock copolymer (P4VP-b-PNLO-b-PS-b-PVPh) was synthesized containing an NLO polymeric segment prepared by step polymerization. The tetrablock copolymer is designed to form an asymmetric lamellar structure by self-assembly prompted by the interactions between the donor and acceptor blocks which are expected to help to align the dipole moments of PNLO block into one direction. The synthesis was carried out by reaction of a P4VP-b-PNLO-Ph-NH 2 block copolymer containing an aniline end group with a poly(4-tert-butyldimethylsiloxy)styrene-b-PS-CO2H (PBDMSS-b-PS-COOH) diblock copolymer containing a tert-butyldimethylsilyl-protected polyvinylphenol endowed with a carboxylic end group in the presence of diphenylphosphoryl azide (DPPA) in N,N-dimethylacetamide. After the formation of the P4VP-b-PNLO-PhNH-CO-PS-b-PBDMSS tetrablock copolymer the PVPh block was obtained by deprotection of tert-butyldimethylsilyl group of the PBDMSS block with tetrabutylammonium fluoride in THF. The PBDMSS-b-PS-COOH precursor was synthesized by initiation of 4-(tertbutyldimethylsilyl)oxystyrene by tert-butyllithium in THF at -78 °C followed by the addition of styrene and end functionalized with dried carbon dioxide gas. The end-functionalized P4VP-b-PNLO-Ph-NH 2 block copolymer was synthesized by step polymerization of 4-(4-(4-fluorophenylsulfonyl)phenyl)sulfonyl-4′-N-ethyl-N-2-(4-hydroxyphenolic)ethylazobenzene and coupling to P4VP-Ph-OH that was endfunctionalized with a phenolic end group followed by end capping with 4-(4-(4-fluorophenylsulfonyl)phenyl)sulfonyl-4′-N-ethyl-N-2-(4-aminophenolic)ethylazobenzene. The end-functionalized P4VP-Ph-OH was synthesized by the 1,1-diphenyl-3,3-dimethylbutyllithium-initiated polymerization of 4-vinylpyridine in THF at -78 °C followed by addition of 4-(tert-butyldimethylsiloxy)bromomethylbenzene.

Block Copolymers: Past Successes and Future Challenges

“…[8] A variety of linear ABC and ABCBA materials were reported in the early 1970s, [9][10][11] but the first ABC star (''miktoarm'') copolymers were not described until 1992. [12,13] Fourcomponent (ABCD) linear [14,15] and miktoarms, [16] and ring-shaped or cyclic block copolymers have also been prepared. [17] LAP has since been demonstrated for dozens of different monomers, which greatly expands the resulting properties beyond the prototypical styrene/diene materials.…”

Morphological change of a diblock copolymer film induced by selective doping of a photoactive chromophore

“…On the other hand, there are not so many studies on the functionalization of a block copolymer film by the introduction of a functional chromophore into a designed part of the microphase structure. However, the introduction of a functional chromophore that exhibits charge transport,6–13 photovoltaic effect,10–13 nonlinear optical effects,9, 14, 15 emission,16 photochromism,17, 18 and so on into a block copolymer is very attractive in view of the recent development of organic electronic and photonic devices.…”

“…Several methods can be adopted for the position‐ selective introduction of a functional chromophore into a block copolymer film: (i) chemical introduction of a functional chromophore to one component or the junction of a block copolymer,6–16 (ii) immersion of a block copolymer film into the solution of a functional chromophore using a solvent that can dissolve only one component,19 and (iii) vapor transportation of a functional chromophore whose compatibility with the two components of a diblock copolymer is different 17, 18. Although chemical introduction is the best method with regard to position selectivity, it lacks versatility, requires intensive processing, and is expensive.…”

Living tert‐butyllithium initiated anionic polymerization of 2‐vinylnaphthalene in toluene‐tetrahydrofuran mixtures

“…Kinetic runs (Table I) were carried out under argon. All high vacuum polymerizations were carried as reported elsewhere 8. Concentrations of t ‐BuLi were determined by reaction with a known excess of recrystallized fluorene in THF at −78 °C.…”