Synthesis and Properties of ABA and ABC Triblock Copolymers with Glassy (A), Elastomeric (B), and Crystalline (C) Blocks

Abstract

We describe the synthesis, characterization, and properties of polystyrene-block-poly-(ethylene-alt-propylene)-block-polyethylene (PS-b-PEP-b-PE) and polystyrene-block-poly(ethylene-altpropylene)-block-polystyrene (PS-b-PEP-b-PS) triblock copolymers. Morphological investigations using TEM, SEM, and SFM reveal for the PS-b-PEP-b-PE triblock copolymers a morphology consisting of PS cylinders and PE crystallites within a matrix of the PEP block, whereas the PS-b-PEP-b-PS triblock copolymer shows interconnected, distorted PS cylinders in the PEP matrix. Mechanical characterization of these triblock copolymers demonstrated that for small strains the PS-b-PEP-b-PE triblock copolymers exhibit the aimed smaller plastic deformations, i.e. better elastic properties, compared to the polystyrenebased ABA type thermoplastic elastomer. However, at high strains the PS-b-PEP-b-PS triblock copolymer shows a significantly better elastic recovery. The high plastic set at high elongations in PS-b-PEP-b-PE triblock copolymers is attributed to the weaker resistance of the PE crystallites compared to amorphous PS domains in the PS-b-PEP-b-PS triblock copolymer.

Anionic Polymerization of Ethylene Oxide in the Presence of the Phosphazene Base ButP4 – Kinetic Investigations Using In‐Situ FT‐NIR Spectroscopy and MALDI‐ToF MS

“…In addition, reports on the synthesis of PEOcontaining block copolymers using the phosphazene base Bu t P 4 [13,16,17,19] and our own experiments on PB-b-PI-b-PEO [18,20] and PS-b-PEO block copolymers did not show any traces of termination or bimodality in the SEC analysis. Figure 13 shows the SEC traces for two PS-b-PEO diblock copolymers including the polystyrene precursors.…”

“…Anionic polymerization of ethylene oxide in the presence of Li þ counterions is of particular interest for the synthesis of poly(ethylene oxide) PEO-containing block copolymers by sequential anionic polymerization. [13,[16][17][18][19][20] Since most of the applicable monomers are commonly polymerized using organolithium initiators, the use of Bu t P 4 has the advantage that the block copolymer can be prepared without an exchange of the cation. In former procedures [21][22][23] the living chain end with a Li þ counterion was first end capped with ethylene oxide to obtain the corresponding OH functionality followed by purification and reactivation of the terminal OH-group with potassium naphthalide or cumyl potassium for the anionic ringopening polymerization of ethylene oxide.…”

“…For example, poly(1,4-butadiene)-block-poly(1,4-isoprene)-block-poly(ethylene oxide) triblock copolymers can be synthesized in a onepot procedure using the phosphazene base Bu t P 4 . [18,20] Subsequent hydrogenation results in the formation of polyethylene-block-poly(ethylene-alt-propylene)-block-poly-(ethylene oxide), a triblock copolymer with two semicrystalline end blocks.…”

Crystallization in ABC Triblock Copolymers with Two Different Crystalline End Blocks: Influence of Confinement on Self‐Nucleation Behavior

“…[2,14] Homogeneous catalytic hydrogenation was carried out in degassed toluene at 100 8C and 90 bar H 2 pressure for 3-4 d using Wilkinson catalyst ((Ph 3 P) 3 Rh I Cl). Under the applied conditions the PB block is hydrogenated completely and the PI block shows an almost complete saturation with ca.…”

Influence of block sequence and molecular weight on morphological, rheological and dielectric properties of weakly and strongly segregated styrene-isoprene triblock copolymers

“…This type of polymers consists of three blocks which can differ from each other (ABC) [28][29][30][31][32][33][34][35][36][37] or can have two similar blocks (ABA) [37][38][39][40][41][42][43]. Numerous studies on synthesis of triblock copolymers via anionic as well as controlled radical polymerization have been published.…”