1,2-Polybutadiene broad molecular weight distribution

When block copolymers have broad molecular weight distributions or when blends of monodisperse block copolymers are prepared, the morphologies may be more complex and are no longer determined by considerations of copolymer composition alone. An example of this is found in the two commercially available K-Resin block copolymers, both of which contain 23 wt % polybutadiene and 77 wt % polystyrene. KRO-1 = 179 Si = 132 kg/mole) exhibits a morphology best described as an interconnected network of randomly wavy cylinders of polybutadiene in a polystyrene matrix as shown in Fig. 10a, whereas KRO-3 = 217 = 106 kg/... 

Oligomeric ethylene oxide terminated with l,2,4-triazoline-3,5-dione has been grafted onto polybutadiene at room temperature in a mixture of tetrahydrofuran and ethylene chloride (53). The product had a broad molecular weight distribution, and energy absorption maxima related to the glass transition temperature of each polymer were apparent. 

Figure 6 shows the 6PC chart of the non-modified polybutadiene. Measurement of GPC was carried out with RI and UV (254 nm) dual detectors. The molecular weight distribution (MWD) obtained by RI detector was very broad. However, the MWO by UV detector cannot be measured because the non-modified polybutadiene gives no UV response. ... 

Over the past decade. Fetters and co-workers have synthesized and studied the chain flexibility of an extremely broad range of well-defined polydienes and polyolefins [36, 38, 39, 143-148]. The polyolefins were prepared by clean and quantitative hydrogenation [144-146] of polydienes of precisely controlled architecture. Thus, poly(l-butene) (a.k.a polyfethyl ethylene)) of an atactic structure and a virtually monodisperse molecular weight distribution was S3m-thesized by hydrogenation of 1,2-polybutadiene made via controlled ( living ) anionic polymerization [144]. Likewise, monodisperse atactic polypropylene... 

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