Microstructure and properties of poly(urethane-siloxane)s based on hyperbranched polyester of the fourth pseudo generation

0391670 - ÚMCH 2014 RIV NL eng J - Journal Article
Pergal, M. V. - Džunuzović, J. V. - Poreba, Rafal - Ostojić, S. - Radulović, A. - Špírková, Milena
Microstructure and properties of poly(urethane-siloxane)s based on hyperbranched polyester of the fourth pseudo generation.
Progress in Organic Coatings. Roč. 76, č. 4 (2013), s. 743-756. ISSN 0300-9440. E-ISSN 1873-331X
R&D Projects: GA ČR GAP108/10/0195
Institutional support: RVO:61389013
Keywords : poly(urethane-siloxane) films * hyperbranched polyester * polysiloxane
Subject RIV: CD - Macromolecular Chemistry
Impact factor: 2.302, year: 2013

Poly(urethane-siloxane) networks based on hydroxyethoxy propyl terminated poly(dimethylsiloxane) (PDMS) as the soft segment and 4,4′-methylenediphenyl diisocyanate (MDI) and two hyperbranched polyesters with different core as the hard segments were characterized by swelling experiments, thermal analyses (DSC and TG), thermomechanical analysis (DMTA), X-ray scattering studies, SEM and AFM analyses, water contact angle and water absorption measurements, as well as surface free energy determination. Hyperbranched polyesters based on 2,2-bis(hydroxymethyl)propionic acid and ethoxylated pentaerythritol or di-trimethylolpropane as core (BH-40 and HBP-4) were used as crosslinkers. Both series are composed of samples having different PDMS (i.e., soft segment) content. The crosslinking density and extent of hydrogen bonding showed an influence on the polyurethane (PU) properties. It was found that higher crosslinking density and better thermal stability of PUs based on BH-40 compared to HBP-4 based PUs are due to the less dense structure of BH-40. DMTA experiments revealed that the networks exhibit two glass transition temperatures, of the soft and hard segments, and one secondary relaxation process. The crosslinking density and extent of the microphase separation increased and thermomechanical properties were improved with decreasing content of PDMS. With increasing PDMS content, the surface of the polyurethane networks became more hydrophobic, the surface free energy decreased and thermal stability was improved. The obtained results revealed that synthesized PUs have good thermal and thermomechanical properties, which can be tailored for the potential use in the coating technology by changing the type of hyperbranched polyester or PDMS content.
Permanent Link: http://hdl.handle.net/11104/0227915