{"doi":"10.1021/acs.macromol.4c02895","title":"Characterization of the Repeat Unit Sequence of Poly(lactide-<i>co</i>-glycolide)","abstract":"Established methods of characterizing repeat unit sequence by measuring changes in comonomer concentration during copolymerization and inferring the resulting copolymer sequence are inapplicable to poly(lactide- co -glycolide) due to reverse and transesterification reactions. In this case, measurement of repeat unit sequences must be based on direct measurement on the copolymer. Here, the assignment of the 13 C NMR spectrum of the glycolyl methylene of poly(lactide- co -glycolide) to specific compositional ester tetrads is reported using insights provided by a stochastic model regression analysis of experimental reversible transesterification copolymerization data. The relative integrals of the deconvoluted compositional tetrad signals can be interpreted within the context of a model for repeat unit clustering that describes the cumulative population of homosequences with at least n G adjacent glycolyl esters, including the resonant glycolyl ester. The decay of the relative population of homosequence length n G is described by an exponential decay f ( n ) = e (1– n )/σ b with the parameter σ b describing the degree of clustering of glycolyl ester units. An empirical model describes the time-evolution of σ b as a function of reaction time, which evolves due to comonomer reversibility and copolymer transesterification.","journal":"Macromolecules","year":2025,"id":520858,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":5,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9553,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1391199,"name":"Michael S. Bingham","orcid":null,"position":1,"is_corresponding":false},{"id":1390731,"name":"Jingyi Dai","orcid":"0009-0008-3422-0382","position":2,"is_corresponding":false},{"id":1391200,"name":"Young Kuk Jhon","orcid":null,"position":3,"is_corresponding":false},{"id":1390732,"name":"Yan Wang","orcid":"0000-0003-1180-8956","position":4,"is_corresponding":false},{"id":1390733,"name":"Bin Qin","orcid":"0000-0002-1995-1768","position":5,"is_corresponding":false},{"id":1390734,"name":"William C. Smith","orcid":"0000-0002-8777-0192","position":6,"is_corresponding":false},{"id":1241257,"name":"Xiaoming Xu","orcid":"0000-0003-1672-0830","position":7,"is_corresponding":false},{"id":288216,"name":"Feng Zhang","orcid":"0000-0002-5377-5841","position":8,"is_corresponding":false},{"id":282389,"name":"Nathaniel A. Lynd","orcid":"0000-0003-3010-5068","position":9,"is_corresponding":false},{"id":1390730,"name":"Louise Kuehster","orcid":"0000-0002-0730-204X","position":0,"is_corresponding":true}],"reference_count":41,"raw_metadata":null,"created_at":"2026-07-19T02:49:32.958846Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}