Fluorescence Quantum Yield of Poly(p-phenylenevinylene) Prepared via the Paracyclophene Route:  Effect of Chain Length and Interchain Contacts

Abstract

The monomer 9-[(tert-butyldimethylsilyl)oxy][2.2]paracyclophan-1-ene (1) is polymerized by Mo(NAr)(CHCMe2Ph)(OCMe(CF3)2)2 (Ar = 2,6-diisopropylphenyl) in a living manner. Block copolymers containing poly(1) and polynorbornene (poly(NBE)) can be prepared and have narrow polydispersities. Treatment of poly(1) with NBu4F produces poly(9-hydroxy[2.2]paracyclophan-1-ene) which dehydrates to poly(p-phenylenevinylene) (PPV) under mild conditions. Block copolymers containing segments of size-specific and defect-free PPV with poly(NBE) of various dimensions can be prepared readily and are soluble in a variety of common organic solvents. These polymers serve as excellent candidates to measure the effect of chain length and frequency of interchain contacts on PPV's fluorescence quantum yield (Φf). Solution and solid-state quantum yield determinations, coupled to fluorescence lifetime measurements, reveal an acute drop in Φf as the degree of polymerization of the emissive species increases and as the average distance between PPV chains decreases. PPV x -block-poly(NBE) y prepared in solution consistently shows larger Φf than material prepared by solid-state dehydration. The poly(NBE) companion block also serves to protect PPV from atmospheric degradation.

Influence of Interchain Interactions on the Absorption and Luminescence of Conjugated Oligomers and Polymers: A Quantum-Chemical Characterization

“…These trends are consistent with recent experimental studies 65,66 showing that highly delocalized conjugated chains do not undergo concentration quenching, as typically observed with dyes; this is why conjugated polymers emerge as highly promising materials for the design of solid-state lasers. 65 III.2.…”

Enhanced Optical Properties and Opaline Self‐Assembly of PPV Encapsulated in Mesoporous Silica Spheres

“…[51] Bazan et al also demonstrated an increase in F f when PPV segments were isolated within a poly(norbornene) matrix. [39] This suggests that the very high quantum yield observed for the PPV@MSS material may be due to the isolation of polymer chains within the mesopores of the silica host. By preventing the formation of interchain excimers, the quantum yield for formation of the fluorescent intrachain excitons is increased.…”

“…A variety of such hosts for PPV have been explored to date. These include porous silica [26][27][28][29][30][31] and alumina, [32] zeolites, [33,34] layered clays, [35,36] amylose, [37,38] poly(norbornene) (PNBE), [39] and vault protein cages. [40] The encapsulated PPV@host materials often possess a variety of properties lacking in the unencapsulated conjugated polymer, including increased fluorescence quantum yield, resistance to photobleaching, liquid crystallinity, and solubility.…”

Structure and properties of p-phenylenevinylene-p-xylylene copolymers prepared by vapor-deposition polymerization

“…The polymer containing PPV fragments with various lengths of conjugated and non conjugated segments may be synthesized through par tial conversion of PPV prepared via various methods [7][8][9] or via copolymerization with different flexible spacers [10][11][12]. For example, a random copolymer was described in [10], while blocks copolymers were reported in [11,12]. Note that the size of PPV blocks in these copolymers does not exceed 10 nm [13], that is, the maximum length of diffusion of excitons [14].…”