In this dataset it refers to claims and abstracts that explicitly address hydrolytic stability, chemical resistance, thermal aging resistance, or environmental durability of polyetheretherketone materials — not just general PEEK composition claims. This is a claims-language filter: a patent covering a PEEK formulation that would happen to be hydrolytically stable but never says so in its title, abstract or claims is excluded. Practitioners should treat the 194 families here as the subset of PEEK patent activity that specifically foregrounds durability performance, which is narrower than total PEEK filing activity.

Filing is concentrated among a small group of specialty-polymer producers, with Solvay-affiliated entities, Victrex, Dow Chemical, SABIC-linked SHPP, Mitsui Chemicals and Asahi Kasei among the recurring names in this space historically. Notably, none of the leading assignees tracked in the recent-momentum data show filings in the latest tracked year, which given the roughly 18-month publication lag may partly reflect timing rather than a full stop in R&D. Co-filing between assignees is rare — only 7 co-assignee pairs appear across all 194 families.

No — filing peaked at 31 families in 2018 and had fallen to a midpoint of 12 by 2022, with the trend continuing downward through the most recent tracked years. This pattern, combined with zero recent-year filings from every leading assignee, suggests the core compositional claim space was largely staked out in the late 2010s. New entrants should expect a maturing field where differentiation increasingly has to come from specific end-use formats rather than base polymer chemistry.

The two most-cited records in this dataset, US4992485A and US4957817A, both cover microporous PEEK membrane formation from non-sulfonating acid solvents and date to 1990-91 — decades before the durability-specific search terms used to build this landscape became common in filings. Their citation counts, 74 and 72 respectively, outrank every more recent durability-labelled filing, meaning that later patents on hydrolytic or chemical resistance in membrane formats are almost certainly building on this foundational art. Any clearance search on PEEK membrane durability should include this earlier art directly, not only recent filings that use durability-specific language.

The IPC composition skews heavily toward base polymer-composition claims (C08L, 152 of 194 families) and away from the specific formats where durability is actually tested in service — separation/filtration (B01D, 23 families) and adhesives (C09J, 18 families). That gap suggests opportunities in claims tied to specific hollow-fiber membrane geometries, adhesive bondline aging under chemical exposure, or laminate thermal-cycling performance, where fewer prior filings compete for the same claim space. A first claim in these areas would likely need to tie a specific durability test protocol to a specific physical format rather than claiming the base PEEK composition alone.