The dynamics of the exchange of chains between micelles formed by diblock copolymers in dilute solution in a selective solvent has been studied using fluorescence measurements. The samples are polystyrene-6Zoc*-poly(oxyethylene) with a single fluorescent label (either naphthalene or pyrene) covalently attached at the junction between the blocks. The critical micelle concentration (cmc) of each sample can be determined from the concentration dependence of the integrated emission intensity, provided the cmc is high enough to permit detection. In order to study the kinetics, micelles of the two differently labeled samples were first prepared at the same concentration, solvent, and temperature, but in two different containers. The contents of the containers were then mixed, and the efficiency of nonradiative singlet energy transfer from naphthalene to pyrene was measured as a function of time. The time dependence of the intensity of the emission from naphthalene can be fitted to a sum of two exponentials, with time constants that differ by at least an order of magnitude. Activation energies are somewhat smaller for the faster process than for the slower process, but in both cases they are on the order of 102 kJ mol-1 under the conditions where they can be measured. We have not been able to account for this result with a kinetic scheme that assumes the exchange of chains between the micelles takes place exclusively via the population of free chains. This difficulty suggests that an additional mechanism for the exchange of chains may be active.

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A series of water-dispersible, surface-active poly(fluorinated oxetane)s was prepared by ring-opening polymerization of fluorinated oxetane monomers using Lewis acid catalysis. The fluorinated oxetane monomers are made by phase-transfer catalytic reaction of a fluorinated alcohol with 3-bromomethyl-3-methyloxetane. Water dispersibility was introduced by conversion of the diol-terminated α,ω-(dihydroxy)poly(fluorinated oxetanes) into diammonium salts of α,ω-sulfate esters. The poly(fluorinated oxetane) salts exhibit unusually low surface tensions for materials based on a pendant trifluoro- or pentafluoroalkyl group. At a critical micelle concentration of ∼10-5 mol/L (∼10-3 wt %), surface tensions of ∼20−30 mN/m are obtained. The novel architecture of the poly(fluorinated oxetane) salts is thought to be responsible for the anomalous surface activity.

Studies of surface tension, adsorption parameters, and dynamic surface tension were performed on a series of bolaamphiphilic α,ω-(diammonium disulfato)poly(fluorooxetane)s of several perfluoroalkyl chain lengths. Similar measurements were performed on a small-molecule, anionic fluorosurfactant with a −C8F17 perfluoroalkyl group that is known to be an effective flow and leveling aid in aqueous coatings. Molecular area demands for the poly(fluorooxetane)s were found to be relatively small for a polymeric species and may indicate a change in conformation between bulk solution and interface. Other adsorption parameters were found to be similar to those of the small-molecule fluorosurfactant. Diffusion coefficients were found to be slightly smaller for the poly(fluorooxetane)s compared to the small-molecule fluorosurfactant.

An α,ω-dihydroxypoly(fluorooxetane) was prepared from a fluorinated oxetane monomer and characterized by matrix-assisted laser desorption ionization mass spectrometric (MALDI MS) and gel permeation chromatographic (GPC) methods. Estimated molecular weights were compared to those derived from NMR spectroscopic end-group analysis. The results of 2-D NMR spectroscopic analysis agreed well with 1-D NMR end-group analytical results and MALDI MS experiments. Because of the small molecular weight of the product, the results from the mass spectroscopic and NMR methods compared favorably. The overestimated molecular weights obtained from GPC are explained by aggregation of the amphiphilic poly(fluorooxetane) in a relatively poor solvent. The robustness of the methods was verified by fractionation of the polymer and subsequent analysis of the fractions by MALDI MS. In addition, information regarding product architecture and copolymerization with THF, which was used to complex the BF3 catalyst, was obtained using tandem mass spectrometry (MS/MS) methods.