Polystyrene-b-polyisoprene

Park I, Lee B et al (2005) Epitaxial phase transition of polystyrene-b-polyisoprene from hexagonally perforated layer to gyroid phase in thin film. Macromolecules 38 10532-10536... 

Visualization of Microphase Separated Morphology of Films of Polystyrene-b-polyisoprene-b-polystyrene... 

Polymer (B) polystyrene-b-polyisoprene diblock copolymer 1997ZHA... 

Fig. 1.7 Polystyrene-b-polyisoprene (PS-b-PI) solid-state morphologies as a function of increasing volume fraction of the polystyrene block (Adapted from [56]).

Polystyrene-b-polyisoprene-b-polystyrene triblock copolymers of different composition were also prepared in a similar... 

The synthesis of a cydic triblock terpolymer, polystyrene-b-polyisoprene-b-poly(methyl methacrylate), was achieved by an end-to-end intramolecular amidation reaction of the corresponding linear a,o)-amino acid precursor [S-b-I-b-Methyl methacrylale (MMA)] under high-dilution conditions. The linear precursor was synthesized by the sequential anionic polymerization of styrene, isoprene, and MMA with 2,2,5,5-tetramethyl-l-(3-lithiopropyl)-l-aza-2,5-disilacydopentane as an initiator and 4-bromo-l,l,l-trimethoxybutane as a terminator. The separation of the unreaaed linear polymer from the cydic terpolymer was fadli-tated by the transformation of the tmreacted spedes into high-molar-mass polymers under high-concentration conditions. The SEC-estimated yield for the final cyclic terpolymer of molar mass of about lOOOOgmor was 90%. 

In 1965 Shell Oil Co. introduced styrenic TPEs, under the trade name Kraton, which are polystyrene-b-polyisoprene(or polybutadiene)- -polystyrene (PS-b-PI(or PBd)- -PS linear triblock copolymers, made by anionic polymerization. Later, BASF introduced styrenic PTEs having tapered blocks (i.e., Styroflex). The typical styrene content of TPEs is between 25 and 40wt.%. When more stable TPEs, toward oxygen. 

Figure 1. Segmental density fluctuation of alternating lamellae of pure polystyrene-b-polyisoprene-b-polystyrene block copolymer. The density (referenced to each pure segment composition) varies between 0 and 1 for each domain phase and in the interphase region which has finite thickness, d. The periodic pattern distance of the lamellae structure is denoted by D.

These losses contribute to heat buildup in the tire and consequent loss in properties such as strength and tear resistance. Since the losses increase with temperature below 100 C the rate of heat generation also increases with temperature, a very unstable situation for tires. This situation also dooms the use of polystyrene-b-polyisoprene-b-polystyrene polymers with low end-block concentrations. In terms of other physical properties, there is no compelling reason to believe that vulcanized block copolymers would be Inferior to other tire rubbers. What limits their consideration here is most likely the higher cost of the block copolymer synthesis. 

SAXS and Rheological Studies on the Order-Disorder and Order-Order Transitions in Mixtures of Polystyrene-b-Polyisoprene-b-Polystyrene and Low Molecular Weight PS... 

Lee W, Cho D, Chang T, Hanley KJ, Lodge TP. Characterization of polystyrene-b-polyisoprene diblock copolymers by liquid chromatography at the chromatographic critical condition. Macromol 2001 34 2353. 

Figure 7.7 (a)-(d) Copolymer fingerprints of the system polystyrene-b-polyisoprene corresponding to... 

Polystyrene-b-polyisoprene diblock copolymer (hydrogenated PIP) N,N-dimethylformamide and methylcyclohexane 93P01... 

Polystyrene-b-polyisoprene diblock copol)mier cyclohexane Enthalpy 335... 

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