The innovation engine for new materials

Laura Rijns

Laura Rijns


Eindhoven University of Technology


Biomedical Engineering


Ryan Barnes

Faculty Sponsor(s): 

Songi Han

Faculty Sponsor's Department: 

Chemistry and Biochemistry

Project Title: 

Probing the Organization of Hyaluronic Acid–Poly L-Lysine (HA-PLL) Coacervates

Project Description: 

In this research the organization and structure of Hyaluronic Acid-Poly L-Lysine (HA-PLL) coacervates is probed. This is a phase-separated liquid-liquid synthetic system, consisting of a dense polymer phase and a dilute water-like phase. The dense phase, consisting of opposite charged HA-PLL polymers, is in nature involved in underwater adhesion of sessile marine organisms to their surface. The organization of the synthetic polymers in the dense phase is probed by analyzing the water dynamics through this dense layer at different densities of the coacervates, which are created by adding the disruptive NaCl to the system. Pulse Field Gradient (PFG) and Overhauser Dynamic Nuclear Polarization (ODNP) are the main methods used for obtaining the diffusion constants of water through this dense polymer layer. Preliminary results show that it can be expected that two different water diffusion constants will exist in the dense phase due to its structure, which is probably like a ‘swiss cheese’ model. The water in the channels should freely diffuse with bulk-like motion, while the hydration water that is close to the surface of the channel should diffuse much slower due to more static interactions with its surface. These water diffusion constants will eventually help us to probe the organization of the polymers; the presence or absence of two or more diffusion constants of water in the dense phase indicates if the coacervate structure is a homogeneous mixture or a more heterogeneous (‘swiss cheese’) structure. Probing the structure of these synthetic polymers in the dense phase will give us better understanding of this coacervate system and will eventually enable possibilities for wet adhesion and superior coating applications.