Surface-confined alternating copolymerization with molecular precision by stoichiometric control.

Area of Science:

• Polymer Chemistry
• Surface Science
• Materials Science

Background:

• Synthesizing sequence-controlled polymers is challenging due to complex kinetics and tedious processes.
• Existing methods struggle to achieve precise control over copolymer sequences.
• Mimicking biological polymers and improving synthetic ones drives research in sequence-controlled copolymerization.

Purpose of the Study:

• To achieve sequence-controlled alternating copolymerization with molecular precision on a surface.
• To develop a thermodynamic strategy for controlling polymerization selectivity.
• To enable selective alternating organometallic copolymerization using stoichiometric control.

Main Methods:

• Surface-assisted synthesis on a Ag(111) surface using silver adatoms.
• Stoichiometric control of comonomer ratios (4,4"-dibromo-p-terphenyl and 2,5-diethynyl-1,4-bis(phenylethynyl)benzene).
• Characterization using scanning tunneling microscopy (STM) and density functional theory (DFT) studies.

Main Results:

• Selective alternating organometallic copolymerization was achieved at a stoichiometric ratio of P-Br:A-H = 2.
• Homopolymerization yield increased when the stoichiometric ratio deviated from 2.
• STM and DFT studies confirmed the mechanism and stoichiometry-dependent polymerization.

Conclusions:

• Stoichiometric control is an effective thermodynamic strategy for sequence-controlled copolymerization on surfaces.
• Surface chemistry enables precise control over copolymer sequence and composition.
• This approach offers a pathway to efficient sequence control in copolymer synthesis.