Sidney R. Knafel, a philanthropist in the fields of education, medical research and the decorative arts, died Dec. 6 at home in Manhattan. He was 91 and died peacefully after a long illness, according to his wife, Londa Weisman.

He was a longtime resident of Chilmark, where he spent many happy hours gardening, exploring trails near Squibnocket Pond (with his gardening pruners), cycling on Moshup Trail and visiting Larsen’s Fish Market and The Net Result. He was a donor to the Polly Hill Arboretum, the Martha’s Vineyard Hospital, Friends of the Chilmark Library and The Farm Institute.

A native of New York, he grew up in Mt. Vernon and served two years in the U.S. Army in Germany. The years in Germany were formative. He explored central Europe in his Volkswagen and learned about German wine and beer. He made enduring friendships with German and French families.

He graduated from Phillips Academy Andover, Harvard University and Harvard Business School. He worked as an investment banker, and later as an investor and entrepreneur. He worked at Lazard Frères before establishing his own private investment company, SRK Management, where he was founder and chairman of Vision Communications, Inc. and Insight Communications Inc.

He was passionate about collecting art and was a leading American collector of 16th to 18th-century French faïence. A portion of his collection was exhibited at the Frick Collection in 2019 and approximately 73 works from it are to become a permanent part of the museum’s decorative arts holdings. He was a trustee of the Frick. With Charlotte Vignon, the Frick’s decorative arts curator, he co-authored The Masterpieces of French Faïence: Selections From the Sidney R. Knafel Collection.

As part of the Sidney R. Knafel Map Collection, he also collected atlases, maps and globes dating from 1434 into the 19th century. In 2011, he donated the collection to the Addison Gallery at Phillips Academy Andover, along with funding for a curator to make the works available to students and scholars. He was particularly interested in ancient maps of Martha’s Vineyard and was intrigued by how the Island and the New England coastline must have struck explorers.

He served as charter trustee emeritus of Phillips Academy and was chairman of the board of its Addison Gallery of American Art. He also was an active participant on a number of Harvard University committees, and was a major donor for the Center for Government and International Studies’ Knafel Building and the Knafel Center at the Radcliffe Institute for Advanced Study.

He was a member of the board of trustees at Wellesley College, where he endowed professorships and student fellowships in honor of his late wife, Susan Rappaport Knafel. He was a trustee emeritus of The Julliard School and chairman of The Rogosin Institute, New York Presbyterian Hospital’s center for research, treatment and education in kidney disease.

He is survived by his wife Londa Weisman of North Bennington, Vt., and New York city; sons Doug Knafel of Stockbridge, Andrew Knafel and his wife Anne Hunter of Shaftsbury, Vt.; grandson Jamie Knafel of Bennington, Vt.; sister Barbara K. Scherlis of Baltimore and West Tisbury; a beloved niece and many beloved nephews, grand-nieces and grand-nephews. He was the brother of the late Helen Mae Askin and her husband Seymour, and the husband of the late Susan Rappaport Knafel.

Because of Covid, a private funeral and interment will be followed by a memorial to be announced at a later date.

Donations can be made to the Environmental Defense Fund.