After receiving a McIntire–Stennis scholarship, he pursued doctoral studies in the United States of America under the supervision of Raymond A.

He got his PhD degree in 1994, after conducting novel research upon the swelling of wood and lignocellulosic materials in water and organic liquids,[5][6][7][8] which has received over 1,000 citations by March 2024.

[13] In October 2020, a meta-research by Ioannidis et al. in the referred journal PLOS Biology, included his name in Mendeley Data 2020, thus acknowledging his research work in the area of wood sciences.

[16][17][18] In October 2023, a meta-research carried out by John Ioannidis et al. at the Stanford University, included Mantanis in the Elsevier Data 2022, where he was ranked at the top 2% of researchers globally in the area of wood science (forestry – materials).

[19][20] In August 2024, Mantanis has acquired the same international distinction for his research work in wood science (Elsevier Data 2023).