Monitoring Polymer Diffusion in a Waterborne 2K Polyurethane Formulation Based on an Acrylic Polyol Latex

• DOI: 10.1021/acs.macromol.0c02129
• Publication Date: 2020-12-01T22:56:15Z
• Authors: Yang Liu; Hang Zhou; Kenneth Tran; Emi Schackmann; Margaret Zhang; Yijie Lu; Kevin Ho; Mohsen Soleimani; Frédéric Lucas; Mitchell A. Winnik
• Keywords: 02 engineering and technology; 0210 nano-technology; 7. Clean energy

We report experiments based upon fluorescence resonance energy transfer (FRET) measurements designed to examine mixing at the molecular level of components a waterborne 2K polyurethane (WB2KPU) formulation. The system consists an acrylic polyol latex (Mn = 4200 g/mol, D̵ 2, Tg ≈ 15 °C) with uniform hydrodynamic diameter (dh) 120 nm plus water-dispersible polyisocyanate (hmPIC, Basonat HW1000 from BASF). prepared labeled phenanthrene (Phen) as donor dye or dimethylaminobenzophenone (Nben) acceptor dye. Dynamic light scattering was used monitor size and distribution in dispersed phase solution. This signal dominated by nanoparticles, which were much larger than tiny droplets formed hmPIC water. Experiments carried out mole ratio NCO/polyol-OH 1.3. found that particle narrow remained unchanged up 22 h after PIC. FRET on samples state well films these dispersions. Films 1:1 mixture (polyol-Phen + polyol-Nben) showed relatively little (ΦET 0.19) even several hours aging ambient temperature, indicating polymer diffusion occurred low-molecular-weight films. In contrast, mixtures polyol-Nben hmPIC) more extensive (ET) 0.51), essentially complete molecules presence hmPIC. key conclusion is reactive plasticizer promotes this faster scale cross-linking reaction. result confirmed examined (hmPIC-Phen polyol-Nben), also between two different components. later system, room temperature led small decrease ΦET over time prominent for aged high humidity (75%) lower (45%). suggests hydrolysis NCO groups film, leading polyurea formation, local separation accompanied net increase average Phen Nben film.