Sequence-Controlled Polymers Through Entropy-Driven Ring-Opening Metathesis Polymerization: Theory, Molecular Weight...

Area of Science:

• Polymer Chemistry
• Materials Science

Background:

• Monomer sequence critically influences copolymer properties, but controlled synthesis of sequenced copolymers is challenging.
• Previous step-growth methods for sequenced poly(lactic-co-glycolic acid)s lacked molecular weight control, scalability, and yield predictability.

Purpose of the Study:

• To develop an efficient, scalable, and controllable method for synthesizing sequenced polyesters.
• To investigate the impact of monomer sequence on polymer properties using a new polymerization technique.

Main Methods:

• Synthesis of sequenced polyesters via entropy-driven ring-opening metathesis polymerization (ED-ROMP) of cyclic macromonomers.
• Incorporation of ethylene glycol and metathesis linkers for ED-ROMP.
• Preparation of cyclic macromonomers using ring-closing metathesis and macrolactonization.
• Utilizing cis-olefins in the metathesis-active segment for selectivity-enhanced (SEED-ROMP).

Main Results:

• Multigram scale synthesis of sequenced polyesters with controlled molecular weights.
• SEED-ROMP demonstrated first-order kinetics and narrow dispersities, indicating enhanced living character.
• Successful preparation of block copolymers, further confirming the living nature of the polymerization.
• Computational analysis revealed cis-macrocyclic olefins enhance polymerization kinetics due to conformational preferences.

Conclusions:

• SEED-ROMP provides a general and effective strategy for producing molecular weight-controlled polymers with precisely incorporated sequenced segments.
• This advancement overcomes limitations of previous methods, enabling broader applications in polymer science.
• The findings pave the way for designing polymers with tailored bulk properties through controlled sequencing.