Dramatically Accelerating II-I Crystal Phase Transition of Polybutene‑1 by In Situ Incorporation of H-Shape...

Area of Science:

• Polymer Science
• Materials Chemistry

Background:

• Isotactic polybutene-1 (i-PB) exhibits a slow II-I crystal phase transition, hindering its melt processing.
• This slow transition limits the practical applications of i-PB.

Purpose of the Study:

• To develop an effective strategy for accelerating the melt crystallization of i-PB.
• To improve the melt processability of i-PB by addressing the slow II-I crystal phase transition.

Main Methods:

• Synthesis of i-PB with H-shape long-chain-branching structures (LCB-i-PB) using ω-alkenylmethyldichlorosilane copolymerization-hydrolysis (ACH) chemistry.
• Utilized Ziegler-Natta or metallocene catalysts for butene-1 polymerization.

Main Results:

• The H-shape long-chain-branching structures significantly enhance chain entanglements in i-PB.
• A substantial acceleration of the entire melt crystallization process, including nucleation, form II crystallization, and the II-I phase transition, was observed.
• The II-I phase transition, typically taking up to a week, was nearly completed within 24 hours for LCB-i-PB.

Conclusions:

• The facile synthesis of LCB-i-PB via ACH chemistry provides an effective solution to the melt processing challenges of i-PB.
• LCB-i-PB demonstrates significantly improved crystallization kinetics, enabling faster and more efficient melt processing.