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Poly (l-lactic acid) (PLLA) and polycarbonate (PCL) grafted Monoamino-Polyhedral oligomeric silsesquioxane (POSS-NH2) (POSS-PLLA and POSS-PCL) by ring-opening polymerization of L-lactide (L-LA) and caprolactone (ε-CL) from POSS-NH2 were obtained in this work. The fourier transform infrared spectrometer (FTIR) results show that the stretching vibration peaks of -C(O)-NH- of POSS-PLLA and POSS-PCL appears at 1650 cm−1 and 1645 cm−1. The crystal diffraction peaks of POSS-PLLA at 22°, 16.7° and 19° are same as the peak positions of PLLA; POSS-PCL at 21.7° 23.7° are same as the peak positions of PCL by X-Ray diffraction (XRD). Both FTIR and XRD results indicate that the grafted products are synthesized successfully. Then, the different contents of POSS-PLLA, POSS-PCL and purchased POSS-polyethylene glycol (POSS-PEG) were blended with PLLA/Poly (d-lactic acid) (PDLA) (with the mass ratio of 1:1) to prepare ternary blends with different contents of polymer grafted POSS. The effects of POSS-PLLA, POSS-PCL and POSS-PEG on the crystallization behavior of PLLA/PDLA were investigated. The results show that compared with POSS-PCL and POSS-PLLA, POSS-PEG enhances the crystallization ability of PLLA/PDLA, and promotes the formation of stereocomplex (SC); on the contrary, POSS-PCL and POSS-PLLA inhibit the formation of SC. [ABSTRACT FROM AUTHOR]

Polystyrene (PS) with great flame retardancy has been achieved by addition of polyhedral oligomeric silsesquioxane (POSS). However, the POSS/PS composite showed easy-ignition behavior leading to fire hazard exposed. Aiming to prolong time to ignition (TTI) and improve flame retardancy simultaneously, using non-flammable modifier to decorate POSS is a facile method. Here, two kinds of POSS hybrids (POSS-ILs), denoted as POSS-EVIM and POSS-VIPSP, were synthesized by free radical copolymerization between vinyl POSS and two kinds of ionic liquid, commercial [EVIm]BF4 and Brønsted ionic liquid, respectively. The polystyrene-based composites (POSS-ILs/PS) were prepared by incorporated POSS-ILs into polystyrene. The results of thermal gravimetric analysis test evidenced that both POSS-ILs increased char yield and decreased decomposed rate of composites. Compared with neat PS, the TTI of POSS-ILs/PS was prolonged by 26 s and 21 s, and meanwhile, the fire hazard was decreased due to reduction of peak value of heat release rate (PHRR) and smoke release rate (PSPR) in cone calorimeter test. Scanning electron microscope observed compact residue of POSS-EVIM/PS and honeycombed residual morphology of POSS-VIPSP/PS, and additionally, both of these residual char possessed higher degree of graphitization than that of PS and POSS/PS in Raman spectrum, suggesting good physical barrier for matrix from heat and oxygen. Besides, the flexural strength of both POSS-ILs/PS composites were increased compared with neat PS. Taking the results above mentioned, POSS modified by ionic liquid can be a decent candidate to prolong time to ignition, simultaneously improve fire safety and mechanical properties for polymeric materials. [ABSTRACT FROM AUTHOR]

Ester-based polyurethane (PU) was found to have excellent shape memory properties with low trigger temperature. Polyhedral oligomeric silsesquioxanes (POSS) have drawn considerable interest due to their hybrid organic–inorganic structures consisting of a silica cage surrounded by eight organic groups. Incorporation of functional POSS in polymers normally improves the mechanical properties of polymer matrix. For the purpose of obtaining shape memory materials with low trigger temperature and quick response, octa(3-hydroxypropyl) polyhedral oligomeric silsesquioxane (POSS-(OH)8) was incorporated into polyurethane by solution casting. The chemical structures and microstructures were characterized by Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD) and field emission scanning electron microscope (FESEM). The thermal properties and dynamic mechanical properties were investigated by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The mechanical properties were also evaluated. Shape memory properties were characterized by cyclic thermal mechanical tests and physical shape recovery tests. The results show that the nanocomposites with low POSS-(OH)8 loading content (1 and 3 wt.%) possess higher breaking strength and elastic modulus, resulting in higher shape fixity, recovery ratios and faster recovery. The nanocomposites might have potential applications for controlling tags or proof marks in the area of low temperature storage. [ABSTRACT FROM AUTHOR]

A novel series of organic-inorganic hybrid materials involving cage-like octa(3-chloroammoniumpropyl)silsesquioxane and Polyvinyl alcohol (OCAPS/PVA) were prepared via solution blending method. The obtained hybrid films were optically transparent and soluble in water. OCAPS/PVA hybrids were characterized by FT-IR, wide-angle X-ray diffraction (WAXD) scanning electronic microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA) and tensile test. The results showed that the hydrogen bond interactions were formed between OCAPS and PVA. OCAPS could be dispersed well in PVA matrix till its content was 10 wt%, while the aggregation and crystallization of OCAPS were observed when the content was up to 15 wt%. The glass transition temperature ( T g) of OCAPS/PVA was found to increase from 53 °C to 60 °C, and the melting temperature ( T m) decreased from 180 °C to 171 °C with increasing OCAPS content from 0 wt% to 15 wt%. The thermal stability of PVA main chain was improved by the addition of OCAPS and the thermal residue ratio also increased. The tensile strength of OCAPS/PVA decreased from 28 MPa to 19 MPa, while the elongation at break of hybrid films increased from 121% to 175%. [ABSTRACT FROM AUTHOR]