Photochemical hole burning study of unimacromolecular micelles with a tetraphenylporphine group embedded in poly(vinyl alcohol)

Nanoscopic Aggregation in Amphiphilic Random Copolymer Bulk Films Studied with Photochemical Hole Burning

“…A methacrylamide containing a free-base TPP residue, 5-(4-(acrylamido)phenyl)-10,15,20-triphenylporphine (AATPP), was synthesized as reported previously. [11] Three terpolymers of AMPS with 49 mol-% CDMAm and 1 mol-% AATPP, poly(A/CD/TPP) (M -w = 3.2 6 10 5 , 3.2 6 10 4 , 2.4 6 10 4 g/mol respectively), were prepared by free radical terpolymerization according to the procedures reported previously. [21] The copolymers of AMPS with 25, 50, 75 mol-% CDMAm or LAMAm were prepared by free radical copolymerization.…”

“…Thus it can be expected that TPP is dissolved preferentially in the hydrophobic nanodomains of CD groups or LA groups in the present amphiphilic random copolymer films. As reported previously [11] the CD-containing terpolymers exist mostly as uni-macromolecular micelles (unimers) TPP) (5.5 nm, 2.6 nm, 2.3 nm)/PVA, and the hypothetical system where CD and AMPS groups are randomly dispersed. The increase in hole width is almost suppressed up to 80 K in TPP/poly(A/CD) (50 : 50) and poly(A/CD/ TPP) (5.5 nm, 2.6 nm, 2.3 nm)/PVA.…”

“…This restricts the segmental motion of the side groups, as we discussed previously. [11] The TPP/poly(A/CD) (50 : 50) and poly(A/CD/TPP)/PVA films show less pronounced increases in hole width than the hypothetical system above 100 K, and the increase in hole width in all the poly(A/CD/TPP)/PVA samples is similar to that in TPP/poly(A/CD) (50 : 50). This means that the increase in hole width due to the local structural relaxation of polymer chains is influenced mainly by the nearest part of the chromophores, i. e., within 2.3 nm.…”

“…[10 c] When tetraphenylporphine (TPP) moieties are covalently incorporated into such amphiphilic polysulfonate copolymers, they are confined ("compartmentalized"") within the hydrophobic clusters. [10 d, e] In our previous papers [11] we extended our study of photochemical hole burning (PHB) from simple amorphous polymers to a polymeric nano-organized system. In a similar manner to our studies of PHB for amorphous polymers, [12 -19] temperature cycle experiments were performed in order to investigate the thermal stability of holes, and structural relaxation in host matrices.…”

“…were prepared by solvent casting from water as reported previously [11]. The TPP-doped sample films, TPP/ poly(A/CD) (75 : 25, 50 : 50) and TPP/poly(A/LA) (75 : 25, 50 : 50), were prepared by solvent casting from a DMF and water (1 : 1) mixed solvent.…”