Dramatically Accelerating II−I Crystal Phase Transition of Polybutene‑1 by In Situ Incorporation of H‐Shape Long‐Chain‐Branching Structures

Abstract This communication reports an effective strategy helping address the long‐troubling melt processing issue of isotactic polybutene‐1 ( i ‐PB) caused by its extremely slow II‐I crystal phase transition. The solution lies in a facile synthesis of i ‐PB containing H‐shape long‐chain‐branching structures (LCB‐ i ‐PB) by applying a so‐called ω ‐alkenylmethyldichlorosilane copolymerization‐hydrolysis (ACH) chemistry to butene‐1 polymerization with Ziegler–Natta or metallocene catalysts. It is evident that the H‐shape LCB structures effectively enhance chain entanglements of i ‐PB and induce an over‐the‐board acceleration of the overall melt crystallization process including nucleation, form II crystallization, and form II‐form I phase transition. As i ‐PB usually requires up to a week to reach equilibrium of the II‐I phase transition, it is found that with LCB‐ i ‐PB such a transition is almost finished within as short as 24 h to even higher degrees.