Extracting structured information from tables in scientific literature is a critical yet challenging task for building domain-specific knowledge bases. This paper addresses extraction of 5-ary polymer property tuples: (POLYMER, PROP_NAME, PROP_VALUE, CONDITION, CHAR_METHOD). We introduce and systematically compare two distinct methodologies: (1) a novel two-stage Hybrid Pipeline that first utilizes Large Language Models (LLMs) for table-to-text conversion, which is then processed by specialized text-based extraction models; and (2) an end-to-end Direct LLM Extraction approach. To evaluate these methods, we employ a systematic, domain-aligned evaluation setup based on the expert-curated PoLyInfo database. Our results demonstrate the clear superiority of the hybrid pipeline. When using Claude Sonnet 4.5 for the linearization stage, the pipeline achieves a score of 67.92% F1@PoLyInfo, significantly outperforming the best direct LLM extraction approach (Claude Sonnet 4.5 at 56.66%). This work establishes the effectiveness of a hybrid architecture that combines the generative strengths of LLMs with the precision of specialized supervised models for structured data extraction.

The growing volume of scientific literature in polymer science presents a significant challenge for researchers attempting to extract and annotate domain-specific entities, such as polymer names, material properties, and related information. Manual annotation of these documents is both time-consuming and prone to error due to the complexity of scientific language. To address this, we introduce PolyMinder, an automated support system designed to assist polymer scientists in extracting and annotating polymer-related entities and their relationships from scientific documents. The system utilizes recent advanced Named Entity Recognition (NER) and Relation Extraction (RE) models tailored to the polymer domain. PolyMinder streamlines the annotation process by providing a web-based interface where users can visualize, verify, and refine the extracted information before finalizing the annotations. The system’s source code is made publicly available to facilitate further research and development in this field. Our system can be accessed through the following URL: https://www.jaist.ac.jp/is/labs/nguyen-lab/systems/polyminder