Surface properties of polyurethane copolymers based on α,ω-dihydroxypropyl-poly(dimethylsiloxane)

Abstract

Polyurethane copolymers based on poly(dimethylsiloxane) represent an important class of thermoplastic elastomers, whirls due to good mechanical and surface properties as well as biocompatibility, may be of interest as biomaterials. In this work, the surface properties of a series of new thermoplastic polyurethanes (TPUs), based on 4,4'-methylenediphenyl diisocyanate and 1,4-butanediol as the hard segments and α,ω-dihydroxypropyl-poly(dimethylsiloxane) (PDMS) as the soft segments, were investigated. The molecular structure and composition of the copolymers were determined by 2D NMR and quantitative 13C NMR spectroscopy. Surface properties of the copolymers were investigated by water contact angle measurements, water absorption and atomic force microscopy (AFM). AFM analysis revealed existence of spherulitic morphology of the copolymers. Also, the results of AFM analysis showed that the coefficient of roughness of TPUs increased with increasing the hard segment content. The hydrophobicity of copolymers increased with increasing the weight fraction of PDMS. This behavior may be ascribed to a tendency of the PDMS segments to migrate on the surface of TPUs caused by its low surface energy.

Poliuretanski kopolimeri na bazi poli(dimetilsiloksana) predstavljaju važnu klasu termoplastičnih elastomera koji zbog izuzetnih mehaničkih i površinskih svojstava, kao i biokompatibilnosti, mogu biti interesantni kao biomaterijali. U ovom radu su ispitana površinska svojstva serije novih termoplastičnih poliuretana (TPUs) sa tvrdim segmentima na bazi 4,4'-metilendifenildiizocijanata i 1,4-butandiola i mekim segmentima na bazi α,ω-dihidroksipropil-poli(dimetilsiloksana) (PDMS). Struktura i sastav TPU su određeni 2D NMR i kvantitativnom 13C NMR spektroskopijom. Površinska svojstva TPU su ispitana određivanjem kontaktnih uglova i merenjem apsorpcije vode, kao i atomskom mikroskopijom sila (AFM). Na osnovu AFM analize uočeno je da kopolimeri pokazuju sferulitnu morfologiju. Takode, rezultati AFM analize su pokazali da se sa povećanjem sadržaja tvrdih segmenata povećavao koeficijent hrapavosti TPU. Hidrofobnost kopolimera je rasla sa povećanjem sadržaja PDMS-a. Ovo ponašanje se može pripisati tendenciji PDMS da migrira na površinu TPU, zbog male površinske energije PDMS-a.