Molecular architectures of four-arm star-shaped styrene-butadiene copolymer

✍ Scribed by Lina Zhang; Zhaocheng Ma; Xiaopeng Xiong; Xiaojuan Xu; Rui Ma; Yang Li

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 93 KB
• Volume: 96
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.21533

✦ Synopsis

Abstract

To understand the molecular architectures of styrene‐butadiene four‐arm star (SBS) copolymers, a size exclusion chromatography combined with laser light scattering (SEC‐LLS) has been used to determine their weight‐average molecular weight (M~w~) and radius of gyration (〈S^2^〉^1/2^), and a new method for the establishment of the Mark‐Houwink equation from one sample has been developed. Based on the Flory viscosity theory, we successfully have reduced the 〈S^2^〉^1/2^ values of numberless fractions estimated from many experimental points in the SEC chromatogram to intrinsic viscosities ([η]). For the first time, the dependences of 〈S^2^〉^1/2^ and [η] on M~w~ for the four‐arm star SBS in tetrahydrofuran at 25°C were found, respectively, to be 〈S^2^〉^1/2^ = 2.62 × 10^−2^ M (nm) and [η] = 3.68 × 10^−2^ M (mL/g) in the M~w~ range from 1.4 × 10^5^ to 3.0 × 10^5^. From data of [η] and 〈S^2^〉^1/2^ for linear and star SBS, we have obtained the information about the branching, namely, the ratios (g and g′) of 〈S^2^〉 and [η] for star SBS to that of the linear SBS of the same molecular weight, which agree with theoretical predictions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 961–965, 2005