@article {49563,
	title = {Thermal properties of polyethylene-grafted sheetlike silsesquioxanes},
	journal = {ACS Applied Polymer Materials},
	volume = {7},
	year = {2025},
	month = {MAR},
	pages = {4290-4300},
	type = {Article},
	abstract = {<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>
},
	keywords = {clay, Crystallization, Nanocomposite, Polyethylene, silsesquioxane},
	issn = {2637-6105},
	doi = {10.1021/acsapm.4c04181},
	author = {Sharma, Vivek and Paulbudhe, Uday and Gupta, Poonam and Zalte, Akshat Shirish and Chikkali, Samir H. and Kumaraswamy, Guruswamy}
}
