During the last two decades Nikos Karayiannis (NK) has gained significant experience in the field of molecular simulations of synthetic and biological polymer systems through extensive collaborations and participations in national and international research projects. As a Ph.D. student, under the advisement of Prof. Doros Theodorou, NK participated in a scientific project with BP-Amoco (2000-2002), which resulted in an intership in BP-Amoco (IL, USA) for the transfer of knowledge on the simulation of the barrier properties of polyester-based materials.H has been a post-doctoral research fellow in ICEHT-FORTH (2002-2006, Greece) and in ISOM/ETSII (2006-2009, UPM, Spain). NK has been involved in three EC-funded multinational scientific projects ("PMILS", "KORRIGAN" and "MNIBS"), three private projects funded by industrial partners (Dow Chemicals, 2002-2004, 2005 and 2006) and two Spanish projects ("HIMOBIOS" and "GANQUBIT"). He has been/is coordinator of the "NAFCA" and "MOSDOP" Spanish projects, both funded by MICINN/FEDER. In 2009 he received a Ramón y Cajal fellowship by the Spanish Ministry of Science and Innovation. In 2010 he became Profesor Contratado Doctor I3 (Associate Professor) at UPM (Spain) and since 2022 he is Profesor Titular I3 (Associate Professor - Civil Servant). He has been visiting researcher in CSIRO (Australia), Harbin Institute of Technology (China) and University of Wisconsin-Madison (USA). He has collaborated in international, private and public projects with industrial companies including among others: BP-Amoco, Dow Chemicals, Rhodia, Accelrys and Borealis.

NK´s main research interests include the simulation studies of the static, dynamic barrier and rheological properties, thermodynamics and phase behavior of synthetic macromolecules of varied molecular architecture and chemical constitution. Special emphasis is placed on the atomistic level of description where advanced Monte Carlo (MC) algorithms are developed and employed for the rapid equilibration of complex, polymer-based systems with an efficiency that outperforms any conventional method. Simulated polymer systems range from densely packed athermal polymers to polyesters and polyolefins in full chemical details. Potential applications include the computer-aided design of novel, colloidal-based materials, biosensors based on liquid crystals and extremely confined thin films. During the last years he has been actively involved in the development of software suite (Simu-D) for the simulation and successive characterization of general atomic and particulate systems.  

He is author of 50 publications (resulting in more than 1700 citations and an h-index of 24), 1 chapter in book and 1 encyclopedia contribution. He has given 8 invited talks and 65 presentations in international conferences and congresses and more than 40 presentations in regular meetings with academic and industrial partners. He is an active reviewer (more than 350 reviews) in more than 50 different scientific journals and academic editor in the journal Crystals ( 16 editorial decisions). He is founding member of the Soft Matter topical group (American Physical Society) and evaluator for ANECA and CSIC (Spain), FONDECYT (Peru) and Marie-Sklodowska-Curie actions and programs (2018-2023).  He is board member of directors of the polyhub network (www.polyhub.org). 

In 2005 NK received the award of "Distinguished scientist" by the Hellenic Ministry of Defense, in 2009 the "Ramón y Cajal" fellowship by the Spanish Ministry of Science and Innovation and in 2023 the "Oustanding Reviewer" recognition by the American Physical Society (APS).

He has been coordinator in 4 and participant in 12 national and international competitive projects with private companies, universities and research centers.

NK has directed 5 research fellowships, 4 diploma, 13 master and 2 doctoral theses and is currently director of 2 master and 3 doctoral theses.