From nano to the macro: tuning hierarchical aggregation of thermoresponsive PEG/PCL-based polyurethanes via molar mass/composition control

Author(s)

Fonseca, Lucas Polo

• Document type: Journal article
• Source: MACROMOLECULAR RESEARCH; v. N/A, p. 13-pg., 2023-03-09.

Abstract

Amphiphilic hyperbranched polyurethanes (HPUs) based on PEG and PCL are promising for several biomedical applications. However, the lack of control over the molar mass and composition hinders a deep understanding of the aqueous self-assembly of HPUs. In this paper, the control over the HPU molar mass and composition was provided by dynamic urea bond-mediated polymerization (DUBMP), enabling a careful evaluation of their aqueous self-assembly by H-1 NMR, DLS, and Cryo-TEM. HPUs containing a single PCL block per chain self-assemble into nanoaggregates (R-h approximate to 10 nm) in water up to its cloud-point temperature (T-cp) of 34 degrees C. On the other hand, HPUs with more than one PCL block per chain self-assemble into nanoaggregates and their clusters below Tcp. In this case, the solution behavior can be tuned by the HPU molar mass. Increasing MW from 4 to 19 kDa, HPUs of similar composition can form colloidally stable cluster suspensions ((M) over bar (W) = 4 kDa) and phase separate into a denser liquid aggregate-cluster phase ((M) over bar (W) = 7 kDa) or into a highly viscous aggregate-network phase ((M) over bar (W) = 19 kDa). This type of control over the hierarchical aggregation of HPUs was reported for the first time and is interesting for biomedical applications. [GRAPHICS] . (AU)

• FAPESP's process: 15/25406-5 - Organizing matter: colloids formed by association of surfactants, polymers and nanoparticles
• Grantee: Watson Loh
• Support Opportunities: Research Projects - Thematic Grants