Novel siloxane based polyurethane nanocomposites

A series of novel thermoplastic polyurethanes (TPUs) nanocomposites based on α,ω–dihydroxy ethoxy propyl poly(dimethylsiloxane) (EOPDMS), 1,4-butanediol (BD) and 4,4'-diphenylmethane diisocyanate (MDI) was synthesized by in situ two-step polyaddition reaction in solution using modified clay (Cloisite 30B). The clay percentage in the nanocomposites was 1, 3, 5, 8 and 10 wt% in relation to the polymers. The aim of this study was to improve some properties of TPUs by the addition of clay nanoparticles. The prepared nanocomposites were characterized using FTIR, AFM and DSC analyses. The influence of nanoparticles dispersion on the morphology and thermal properties of TPUs was investigated

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

Evaluation of Relationship Between Sleep Bruxism and Headache Impact Test-6 (HIT-6) Scores: A Polysomnographic Study

Sleep bruxism (SB) is a masticatory muscle activity during sleep characterized by teeth clenching or grinding and/or bracing or thrusting of the mandible. Morning headache is considered as a common symptom of SB; however, the relationship between SB and headache and its impact on patient's life is not clear. Therefore, the present study aimed to assess the relationship between SB using polysomnography with video/audio recording and Headache Impact Test-6 (HIT-6) scores. SB was evaluated in respondents by single-night diagnostic polysomnography with video/audio recording. The study found that Bruxism Episode Index was similar in the group with significant impact of headache on patient's life (HIT-6 score ≥ 50) and in group with little or no impact (HIT-6 score < 50). A statistically significant positive correlation was observed between bruxism associated with arousal and HIT-6 score (r = 0.51, p < 0.05) and between mixed bruxism and HIT-6 score (r = 0.58, p < 0.05) in the subgroup with phasic bruxism. The results indicated the relationship between SB and impact of severity of headache on the patient's life measured by HIT-6 is only modest. It was also found that the impact of severity of headache measured by HIT-6 is altered only in those with phasic bruxism and is associated with arousal. Further research should elucidate the factors influencing the relationship between SB and headache.Trial Registration: Clinical Trials NCT03083405, WMU1/2017, https://clinicaltrials.gov/ct2/show/NCT0308340

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

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. From these studies, structure-property relationships were elucidated. 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 for the samples of different series. 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

Cardiovascular Implications of Sleep Bruxism—A Systematic Review with Narrative Summary and Future Perspectives

Sleep bruxism is a common sleep-related behavior characterized as repetitive masticatory muscle activity. Genetic vulnerability to stress and anxiety is considered a basal component in the pathogenesis of bruxism events. Dysfunction of the autonomic nervous system related with an arousal during sleep is considered an underlying cause of the cardiovascular implications of sleep bruxism. Increased cardiovascular risk was previously linked with sleep conditions: for example, obstructive sleep apnea and insomnia, and sleep bruxism. The aim of present systematic review was to evaluate the current arguments on the relationship between sleep bruxism and cardiovascular diseases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We have reviewed the Embase, PubMed (Medline) and Scopus databases to identify applicable articles (1994–2021). A total of 127 records in English language were identified, then after screening and exclusion of nonrelevant records, 19 full-text articles were evaluated. Finally, we included 12 studies for synthesis. Due to the heterogeneity of the compared studies, only a qualitative comparison and narrative summary were performed. In the majority of studies, increased sympathetic activity was successfully established to escalate heart rate variability, the inflammatory process, oxidative stress, endothelial remodeling and hormonal disturbances, leading to hypertension and other cardiovascular complications

Termička i morfološka svojstva termoplastičnih poliuretana na bazi poli(propilenoksida)-b-poli(dimetilsiloksana)-b-poli(propilenoksida)

In this paper was investigated the influence of the content of soft poly(propylene oxide)-b-poly(dimethylsiloxane)-b-polY(propylene oxide) (PPO-PDMS) segments on the thermal and morphological properties of new thermoplastic polyurethane with TGA, DSC and AFM analyses as well as deconvolution of FTIR spectra. The thermal stability of the copolymers increased, while the degree of crystallinity decreased with increasing content of PPO-PDMS segments. AFM and FTIR analysis confirmed that with decreasing of the content of PPO-PDMS segments the degree of microphase separation in copolymers increased.U ovom radu ispitan je uticaj sadržaja mekih poli(propilenoksida)-b-poli(dimetilsiloksana)-b-poli(propilenoksida) (PPO-PDMS) segmenta na termička i morfološka svojstva novih termoplastičnih poliuretana pomoću TGA, DSC i AFM analiza kao i dekonvolucijom FTIR spektara. Termička stabilnost kopolimera se povećavala, dok se stepen kristaliničnosti smanjivao sa povećanjem sadržaja PPO-PDMS segmenata. AFM i FTIR analize su potvrdile da se sa smanjivanjem sadržaja PPO-PDMS segmenata povećavao stepen mikrofaznog razdvajanja kopolimera

The Effect of Cadmium on Sleep Parameters Assessed in Polysomnographic Studies: A Case–Control Study

Cadmium is a heavy metal that accumulates in the body due to environmental and occupational exposure. The main form of environmental exposure to cadmium is related to cigarette smoking. The primary aim of this study was to evaluate the effect of cadmium on numerous sleep parameters with the use of polysomnography. The secondary aim of this study was to investigate if environmental exposure to cadmium is a risk factor for the intensity of sleep bruxism (SB). Methods: A total of 44 adults underwent a full night of polysomnographic examination. The polysomnograms were assessed according to guidelines set out by the American Academy of Sleep Medicine (AASM). The concentration of cadmium in the blood and urine was determined spectrophotometrically. Results: The polysomnographic examination confirmed that cadmium, age, male gender and smoking status are independent risk factors for an increase in the apnea–hypopnea index (AHI). Cadmium alters sleep architecture by favoring sleep fragmentation and decreasing the duration of the rapid eye movement (REM) phase of sleep. However, cadmium exposure is not a risk factor for the development of sleep bruxism. Conclusions: In summary, this study demonstrates that cadmium affects sleep architecture and is a risk factor for the development of obstructive sleep apnea; however, it does not affect sleep bruxism

Studies of the Thermal and Mechanical Properties of Poly(urethane-siloxane)s Cross-Linked by Hyperbranched Polyesters

Polyurethane networks based on Boltorn hyperbranched polyesters (HBPs) of different pseudogenerations as cross-linkers, alpha,omega-dihydroxy(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS-EO) and 4,4'-methylenediphenyl diisocyanate were synthesized using a two-step polymerization reaction in solution. The influence of the pseudogeneration number of Boltorn HBPs on the thermomechanical and thermal properties and morphologies of polyurethane networks was investigated using FTIR, DMTA, TGA, hardness measurements, SEM, and SAXS. Synthesized polyurethanes showed higher cross-linking density and hardness and lower thermal stability with increasing pseudogeneration number of HBP. Samples with lower EO-PDMS-EO content exhibited slightly better thermal stability and higher hardness. All utilized characterization methods yielded consistent results and confirmed the existence of microphase separated morphology with the appearance of certain microphase mixing between segments as the pseudogeneration number of HBP increased. The obtained results revealed that the synthesized polyurethanes have good thermal and thermomechanical properties, which can be tailored by changing the pseudogeneration number of the HBP or the EO-PDMS-EO content