01965nas a2200253   4500008004100000022001400041245011400055210006900169260000800238300001400246490000600260520113300266653001301399653000901412653001801421653001701439653001901456100001801475700002001493700002201513700002401535700002701559856012501586       2023                        eng d  a2637-610500aPolyethylene-grafted sheet-like silsesquioxane nanocomposites with unprecedented adhesion to polar substrates0 aPolyethylenegrafted sheetlike silsesquioxane nanocomposites with  cJUL  a5972-59830 v53 a<p>
	Polyethylene is a highly apolar polymer with very pooradhesionto most substrates, necessitating the use of tie layers. Therefore,the synthesis of functional polyethylene is a long-standing challengein catalytic ethylene polymerization. Here, we report the preparationof a nanocomposite comprising polyethylene covalently grafted ontosheet-like silsesquioxanes, with unprecedented adhesion to metal andglass. A norbornene-grafted, layered Mg-silsesquioxane is treatedwith Grubbs second-generation catalyst (G-II), and the identity ofcovalently tethered G-II is unambiguously ascertained. Covalentlytethered G-II catalyzes the ring opening metathesis polymerizationof cyclooctene to poly(cyclooctene). The resulting poly(cyclooctene)is catalytically hydrogenated to yield polyethylene. This polyethylenenanocomposite exhibited a bonding strength of the order of 100 MPaon stainless steel and aluminum, 10-fold higher than reported forengineered polyethylene copolymers. The nanocomposite exhibits anincrease in the polar component of surface energy, yet remains compatibleand cocrystallizes with a polyethylene matrix.</p>
10aadhesion10aclay10aNanocomposite10aPolyethylene10asilsesquioxane1 aSharma, Vivek1 aPaulbudhe, Uday1 aBachhar, Nirmalya1 aChikkali, Samir, H.1 aKumaraswamy, Guruswamy  uhttps://library.ncl.res.in/content/polyethylene-grafted-sheet-silsesquioxane-nanocomposites-unprecedented-adhesion-polar02521nas a2200265   4500008004100000022001400041245007300055210006900128260000800197300001400205490000600219520170800225653000901933653002001942653001801962653001701980653001901997100001802016700002002034700001802054700002702072700002402099700002702123856010502150       2025                        eng d  a2637-610500aThermal properties of polyethylene-grafted sheetlike silsesquioxanes0 aThermal properties of polyethylenegrafted sheetlike silsesquioxa  cMAR  a4290-43000 v73 a<p>
	Polyethylene-grafted layered silsesquioxanes, termed polyethylene-clays (PEC), are nanocomposites comprising polyethylene chains tethered to inorganic sheets with a phyllosilicate-like structure. Here, we report that these nanocomposites show two-stage crystallization on cooling, qualitatively different from previous reports on polyethylene nanocomposites. We employ differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS) to study the melting and crystallization of PEC. End tethering of the polyethylene chains to a nanosheet strongly influences the manner in which PEC crystallizes from the melt on cooling. PEC exhibits two-step crystallization, characterized by a sharp high-temperature exotherm, followed by a broader exotherm at lower temperatures, in contrast to a single sharp exotherm for neat polyethylene. SAXS indicates that lamellar stacks form at high temperatures and that the low-temperature exotherm corresponds to the formation of additional lamellae and their insertion within these stacks. PEC exhibits lower peak melting temperature, lower crystallinity, and a wider melting range relative to polyethylene. We show that the progress of crystallization of PEC is determined by its ultraslow relaxation dynamics. In contrast, PEC in xylene solution exhibits a significantly shorter relaxation time than the melt PEC. Such systems exhibited a single exotherm on cooling and SAXS structure factor peaks with peak positions in a ratio of 1:2. We hypothesize that the high melt viscosity inhibits the crystallization-induced decrease in the specific volume of PEC, resulting in tensile internal stresses that determine the observed thermal behavior.</p>
10aclay10aCrystallization10aNanocomposite10aPolyethylene10asilsesquioxane1 aSharma, Vivek1 aPaulbudhe, Uday1 aGupta, Poonam1 aZalte, Akshat, Shirish1 aChikkali, Samir, H.1 aKumaraswamy, Guruswamy  uhttps://library.ncl.res.in/content/thermal-properties-polyethylene-grafted-sheetlike-silsesquioxanes