Dielectric relaxation of styrene-isoprene diblock copolymer solutions: a selective solvent system

Rheological and Dielectric Behavior of a Styrene−Isoprene−Styrene Triblock Copolymer in Selective Solvents. 2. Contribution of Loop-Type Middle Blocks to Elasticity and Plasticity

“…Since the B blocks had no parallel dipoles and their global motion was dielectrically inert, the slow modes commonly seen for SI and SB were related to the domain structures. 22 Intensities of those modes were found to decrease with increasing T. 22 This feature is in contrast to that of the slow modes (up-turn of ′′) of our SI/ C 14 system. Thus, the slow dielectric modes appear to have different origins for our systems (having = 30/70 S/I composition) and the systems examined by Yao et al 22 and σ y (l,i) of the bridges and interdigitated loops are determined by the mixing barrier for the S and I blocks.…”

Dielectric Relaxation of Type-A Polymers in Melts and Solutions

“…The mica sheets themselves had a negligibly small dielectric loss. [36] For this dielectric set-up, an analysis indicates that the out-of-phase component of the observed complex capacitance C99 and the dielectric loss e99 of the PI layer are related to each other as: [36] e99(x)/e99 peak = C99(x)/C99 peak (39) (This relationship is obtained under an assumption that PI layers have the same e99 in the contact area and the outside area where the layers are separated by the air gap; see insert of Figure 30). …”

“…Instead, this penalty results from the uniform space-filling requirement. In fact, the dielectric mode distribution becomes narrower when the I lamellae are selectively swollen with tetradecane: [39] The osmotic requirement of uniform concentration profile in the swollen lamellae still constrains the I block motion, but this requirement is weaker than the space-filling requirement in the bulk lamellae. This leads to the mode distribution being narrower in the swollen lamellae.…”

Dielectric studies on the dynamics of polymer chains in various environments

“…SI Solutions in a Selective Solvent: We then examined solutions of SI in n-tetradecane (C14) that dissolves only I-blocks but precipitates S-blocks (an I-selective solvent) (Ref. 27). When the I-selective solvent is added to bulk SI, the solvent goes almost exclusively into the I-phase which is thus swollen, while the S-domains still remain rigid.…”

“…Once the micelles are formed, the structure of each micelle, e.g., the number of the block copolymer chains involved in one micelle, is virtually unchanged upon further dilution and they simply become vs log(m/q,,,) for n-tetradecane ) from 100 dispersed as a suspension, because n-tetradecane is a strongly I-selective solvent and S-cores remain rigid. In fact, for SUC14 solutions the E" vs o curve (responsible for the normal modes of the I-brushes) becomes sharper and shifts to the high-o side with decreasing &I in a rather complicated manner (Refs.25,27). With further decreasing &I the shape of the E"VS ( u / u , , ) curve approaches that of star-shaped PVC14 solutions close to that of PVC14 solutions independent of &I, as we have anticipated.…”