Poly(urethane-siloxane) networks based on hyperbranched polyester: mechanical and thermal properties

Mechanical and thermal properties, hardness as well as degree of microphase separation of novel poly(urethane-siloxane) networks based on hyperbranched polyester of the forth pseudo generation were investigated using a variety of experimental methods. According to the combined results obtained from DSC and DMTA experiments, these networks exhibit two glass transition temperatures, of the soft and hard segments, and one secondary relaxation process. The results showed increase of crosslinking density and microphase separation and improvement of mechanical properties with decreasing content of soft ethylene oxide-poly(dimethylsiloxane)-ethylene oxide segment

Ispitivanje morfologije i površinskih svojstava umreženih poli(uretan-estar-siloksana)

Two series of crosslinked poly(urethane-ester-siloxane)s were synthesized from α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS- -EO), 4,4'-methylenediphenyl diisocyanate and Boltorn® hyperbranched polyesters of the second and third pseudo generation, by two-step polymerization in solution. The effect of the EO-PDMS-EO content and functionality of the applied crosslinking agent on the morphology and surface properties of the prepared poly(urethane-ester-siloxane)s was investigated by FTIR spectroscopy, small-angle X-ray scattering (SAXS), atomic force microscopy (AFM), scanning electron microscopy (SEM) and water absorption measurement. Different techniques (FTIR peak deconvolution, SAXS and AFM) revealed that decrease of the crosslinking agent functionality and EO-PDMS-EO content promotes microphase separation in the synthesized poly(urethane-ester-siloxane)s. SEM analysis and water absorption experiments showed that, due to the hydrophobic character of EO-PDMS-EO and its ability to migrate to the surface of poly(urethane-ester-siloxane)s, samples synthesized with higher EO-PDMS-EO content and crosslinking agents of lower functionality had more hydrophobic surfaces and better waterproof performances. The obtained results indicate that the synthesis of poly(urethane-ester-siloxane)s based on EO-PDMS-EO and Boltorn® hyperbranched polyesters leads to the creation of networks with interesting morphological and surface properties, which can be easily tailored by changing the content of EO-PDMS-EO segment or functionality of hyperbranched polyester.U ovom radu sintetisane su dve serije umreženih poli(uretan-estar-siloksana) (PUS) korišćenjem α,ω-dihidroksi-(etilenoksid-poli(dimetilsiloksan)-etilenoksida) (EO-PDMS-EO), 4,4'-diizocijanatodifenilmetana i dva Boltorn® hiperrazgranata poliestra (HRP) druge i treće pseudo generacije kao umreživača. Svaka serija se sastoji od uzoraka koji imaju različiti udeo mekog segmenta (EO-PDMS-EO). Uticaj funkcionalnosti korišćenog HRP i udela mekog segmenta na morfologiju i površinska svojstva PUS ispitan je primenom FTIR spektroskopije, SAXS, AFM i SEM analize i merenjem količine apsorbovane vode. Pokazano je da sa smanjenjem funkcionalnosti umreživača i udela EO-PDMS-EO dolazi do povećanja stepena mikrofaznog razdvajanja kod sintetisanih PUS. Pored toga, uzorci PUS sa većim udelom mekog segmenta i sintetisani primenom HRP niže funkcionalnosti pokazuju bolju otpornost na vodu

Mechanical and Thermal Properties of Poly(urethane-ester-siloxane) Networks

U ovom radu ispitana su svojstva poli(uretan-estar-siloksana) na bazi α,ω-dihidroksi-(etilenoksid-poli(dimetilsiloksan)-etilenoksida) (EO-PDMS-EO), 4,4'-diizocijanatodifenilmetana i alifatskog Boltorn® hiperrazgranatog poliestra druge pseudo generacije, kao umreživača. Sintetisano je pet uzoraka umreženih poliuretana sa različitim udelom mekih segmenata (EO-PDMS-EO) primenom dvostepene reakcije polimerizacije u rastvoru. Uticaj udela EO-PDMS-EO na mehanička i termička svojstva umreženih poli(uretan-estar-siloksana) ispitan je dinamičko-mehaničkom analizom (DMA), diferencijalnom skenirajućom kalorimetrijom (DSC) i merenjem tvrdoće. Dobijeni rezultati ukazuju da smanjenje udela EO-PDMS-EO utiče na povećanje stepena mikrofazne separacije sintetisanih uzoraka. Istovremeno dolazi do povećanja gustine umrežavanja, heterogenosti mreže i poboljšanja mehaničkih svojstava umreženih poli(uretan-estar-siloksana). Korišćenjem DMA određene su vrednosti temperature ostakljivanja mekih i tvrdih segmenata, kao i temperature koje odgovaraju sekundarnom relaksacionom procesu. Rezultati prikazani u ovom radu ukazuju da se kombinacijom makrodiola na bazi poli(dimetilsiloksana), hiperrazgranatog poliola i odgovarajućeg diizocijanata mogu sintetisati umreženi poliuretanski materijali odgovarajućih termičkih i mehaničkih svojstava za tačno određenu namenu.Properties of poly(urethane-ester-siloxane)s based on α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS-EO), 4,4'-methylenediphenyl diisocyanate and aliphatic Boltorn® hyperbranched polyester of the second pseudo generation as crosslinking agent were investigated in this work. Five samples of polyurethane networks having different soft segment (EO-PDMS-EO) content were synthesized using two-step polymerization reaction in solution. The effect of EO-PDMS-EO content on the mechanical and thermal properties of poly(urethane-ester-siloxane) networks was investigated using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and hardness measurements. Obtained results revealed that decrease of EO-PDMS-EO content enhanced microphase separation in the synthesized networks. Simultaneously, increase of the hard segment content improved mechanical properties and induced increase of the crosslinking density and network heterogeneity of poly(urethane-ester-siloxane)s. DMA results revealed existence of two glass transition temperatures, of the soft and hard segments and the presence of secondary relaxation process. Results presented in this work indicate that this specific combination of poly(dimethylsiloxane)-based macrodiol, hyperbranched polyol and adequate diisocyanate can be applied to obtain polyurethane networks of good thermal and mechanical properties, which can be relatively easily tailored for exact application requirements by changing soft/hard segment ratio

Proučavanje morfologije i termomehaničkih svojstava umreženih poli(uretan-siloksana) na bazi hiperrazgranatog poliestra

Two series of polyurethane films based on hyperbranched polyester of the second pseudo-generation (Boltorn®), 4,4'-methylenediphenyl diisocyanate and two different siloxane prepolymers, α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide)(EO-PDMS-EO) and α,ω-dihydroxypropyl-poly(dimethylsiloxane) (HP-PDMS), were prepared by two-step polymerization in solution. The influence of the type and content of soft segment on the morphology, thermomechanical and surface properties of the synthesized polyurethanes was studied by atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), dynamic mechanical thermal analysis (DMTA) and water absorption measurements. It was found that these techniques confirmed existence of microphase separated morphology. Synthesized polyurethanes exhibited two glass transition temperatures and one second relaxation process. The results showed that polyurethanes based on HP-PDMS had higher surface roughness, better microphase separation and waterproof performances. Samples synthesized with lower PDMS content had less hydrophobic surface, but higher crosslinking density and better thermomechanical properties.U ovom radu pripremane su dve serije poliuretanskih filmova na bazi hiperrazgranatog poliestra druge pseudo generacije (Boltron), 4,4¢-metilendifenildiizocijanata i dva različita iloksanska pretpolimera kao što su a, ω-dihidroksi- (etilenoksid-poli(dimetilsiloksan)-etilenoksid)(EO-PDMS-EO) i a,ω-dihidroksipro-pilpoli(dimetilsiloksan)(HP-PDMS), dvostepenom polimerizacijom u rastvoru. Uticaj vrste i sadržaja mekog segmenta na morfologiju, termomehanička i površinska svojstva sintetisanih poliuretana je proučavan pomoću mikroskopije atomske sila (AFM), rasipanja X-zraka pod malim uglovima (SAXS), skenirajuće elektronske mikroskopije (SEM), dinamičko mehaničke termičke analize (DMTA) i merenja količine apsorbovane vode. Nađeno je da primenjene tehnike potvrđuju postojanje morfologije mikrofaznog razdvajanja. Sintetisani poliuretani pokazivali su dve temperature ostakljivanja i jedan sekundarni relaksacioni proces. Rezultati su pokazali da poliuretani na bazi HP-PDMS su imali veći koeficijent hrapavosti, bolje mikrofazno razdvajanje i bolju otpornost prema vodi. Uzorci sintetisani sa nižim sadržajem PDMS-a su imali manju hidrofobnost, ali veću gustinu umrežavanja i bolja termomehanička svojstva

Supplementary material for the article: Stefanović, I. S.; Špírková, M.; Poreba, R.; Steinhart, M.; Ostojić, S.; Tešević, V.; Pergal, M. V. Study of the Properties of Urethane-Siloxane Copolymers Based on Poly(Propylene Oxide)-b-Poly(Dimethylsiloxane)-b-Poly(Propylene Oxide) Soft Segments. Industrial and Engineering Chemistry Research 2016, 55 (14), 3960–3973. https://doi.org/10.1021/acs.iecr.5b04975

Supplementary material for: [https://doi.org/10.1021/acs.iecr.5b04975]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1918

Povrchové a mechanické vlastnosti organicko/anorganických nanokompositních nátěrů

Surface hardness of transparent colorless epoxy-based organic-inorganic nanocomposite coatings was investigated by atomic force microscopy, nanoindentation and the Persoz pendulum test. The influence of mechanical properties on the measured surface characteristics is discussed

Modification of epoxy resins with thermoplastic segmented polycarbonate-based polyurethanes

In this work, epoxy hybrid materials were synthesized by addition of thermoplastic segmented aliphatic polyurethanes with good elastic properties. The modified epoxy samples were obtained by curing of previously homogenized mixture of prepared polyurethane melts, epoxy resin and crosslinking agent Jeffamine D-2000. The influence of different weight content of polyurethanes (5, 10 and 15 wt. % compared to pure epoxy resin) as well the influence of different hard segments of elastomers (20, 25 and 30 wt. %) on the curing of modified epoxy systems was studied. The curing was followed by differential scanning calorimetry (DSC), in dynamic regime from 30 to 300°C, at three heating rates (5, 10 and 20°C/min). With the increase of hard segments content of polyurethanes added in higher concentration (10 and 15 wt. %) into epoxy matrix, the temperature of maximum ratio of curing was shifted to lower values (from 205 to 179°C). Obtained DSC data were analyzed using two integral methods (Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose) and one differential kinetic model (Friedman). The significant differences were observed in the second part of the epoxy curing (for the reaction degrees higher than 60 %), where the values of activation energies remarkably increase. The addition of polyurethane elastomers retarded the curing process due to decreased mobility of reactant molecules caused by higher viscosity of reaction mixture. By detailed analysis of determined kinetic parameters, it is concluded that the influence of slow diffusion is more pronounced in the presence of thermoplastic polycarbonate-based polyurethanes, which confirmed their effect on the mechanism of epoxy curing. The highest tensile strength and hardness showed the DGEBA modified with the polyurethane with highest hard segment content. Increasing the hard segment content of polyurethane and its concentration in matrix, the tensile strength of modified epoxy was increased. The elongation at break of modified epoxy samples was significantly improved by addition of polycarbonate-based polyurethanes with low hard segment content, due to higher content of flexible soft segment chains. [Projekat Ministarstva nauke Republike Srbije, br. III 45022), i Pokrajinski Sekretarijat za nauku i tehnološki razvoj (projekat 114-451-2396/2011-01). Autor iz Praga duguje zahvalnost „the Grant Agency of the Czech Republic“ (Czech Science Foundation, project No. P108/10/0195).