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Series of gels covering a wide range of crosslink ratios (from 1/1000 to 1/5) have been obtained by connecting poly(3-n-octylthiophene) chains with trithienylbenzenes. We have observed the variation of the swelling ratio, the glass transition temperature and the molecular weight (of the related soluble fractions) of the undoped networks with the crosslink ratio. These quantities exhibit a continuous change. This result is an indication of the homogeneity of the gel structures. Besides, we point out characteristics of the transport properties related to the connectivity.

Conductivity has been measured as a function of time ta during aging, and as a function of temperature for different aging times, on differently doped polypyrrole (PPy) in various conditions. We show that for the samples aged below 150 °C, a single expression describes both the temperature and the aging time dependences of the conductivity, In σ(ta,T) α −(ta / T)1/2. This corresponds to a hopping process between conducting grains separated by expanding insulating barriers upon aging. Moreover, the aging kinetics for different temperatures can be deduced from each others with scaling laws. The relative stabilities of PPy with various dopants have been compared. Slight deviations from the above behaviour, observed when aging above 150 °C, can be accounted for by a generalization of the model.

Series of gels covering a wide range of crosslink ratios (from 1/1000 to 1/5) have been obtained by connecting poly(3-n-octylthiophene) chains with trithienylbenzenes. We have observed the variation of the swelling ratio, the glass transition temperature and the molecular weight (of the related soluble fractions) of the undoped networks with the crosslink ratio. These quantities exhibit a continuous change. This result is an indication of the homogeneity of the gel structures. Besides, we point out characteristics of the transport properties related to the connectivity.

Thermal variations of both the conductivity (σ) and the thermopower (S) have been measured on polyaniline (PANI) films protonated by camphor sulfonic acid (CSA) in m-cresol, after aging at 130°C in air for times up to 30 days. We show that, with increasing disorder: i)the temperature dependence of σ changes continuously from a very flat one to another which is of the type σ(T) ∞ exp(-(T0/T)1/2), as observed in HCI doped PANI and ii) a U-shaped contribution, similar to that one observed in PANI-HCI, is progressively added to the linear temperature dependence of the thermopower in pristine PANI-CSA. We show that all the data can be accounted for in a single heterogeneous picture of metallic regions separated by insulating barriers, the major effect of aging being a broadening of the barriers at the expense of the grains.

Fluorescence resonance energy transfer (FRET) was used to study hybrid formation and dissociation after microinjection of ollgonucleotldes (ODNs) Into living cells. A 28-mer phosphodiester ODN ( + PD) was synthesized and labeled with a 3′ rhodamlne (+ PD-R). The complementary, antisense 5′-fluoresceln labeled phos-phorothioate ODN (– PT-F) was specifically quenched by addition of the + PD-R. In solution, the – PT-F/ + PD-R hybrid had a denaturatlon temperature of 65 ± 3°C detected by both absorbance and FRET. Hybridization between the ODNs occurred within 1 minute at 17 μM and was not appreciably affected by the presence of non-specific DNA. The pre-formed hybrid slowly dissociated (T1/2 = 3 h) In the presence of a 300-fold excess of the unlabeled complementary ODN and could be degraded by DNAse I. Upon microinjection into the cytoplasm of cells, pre-formed fluorescent hybrids dissociated with a half-time of 15 minutes, which is attributed to the degradation of the phosphodiester. Formation of the hybrid from sequentially Injected ODNs was detected by FRET transiently in the cytoplasm and later In the cell nucleus, where nearly all injected ODNs accumulate. This suggests that antisense ODNs can hybridize to an Intracellular target, of exogenous origin In these studies, In both the cytoplasm and the nucleus.