Glass transition temperature (T g) is a fundamental property of a polymer that defines its upper service temperature for structural applications and is often indicative of its other thermophysical features. This paper investigates how vapor-phase infiltration (VPI), which infuses polymers with inorganic species to create organic–inorganic hybrid materials, affects the material’s glass transition temperature. We examine VPI of aluminum oxide (Al2O3 or AlO x ) into poly­(styrene-r-2-hydroxyethyl methacrylate) (PS-r-PHEMA) random copolymer thin films using trimethylaluminum (TMA) and water (H2O) precursors. These VPI precursors are intended to be unreactive toward the styrene monomer units and highly reactive toward the HEMA monomer units. Experiments were conducted on PS-r-PHEMA thin films (200 nm) spun-cast onto silicon wafers and infiltrated at 100 °C with 4 h exposure times. Copolymers with varying fractions of HEMA units were investigated, from 0 to 20.2 mol % HEMA. Volumetric swelling of the films after VPI and aluminum oxide film thicknesses after pyrolysis both confirm higher metal oxide loading in polymers with higher HEMA fractions. T g was measured by tracking film thickness as a function of temperature using spectroscopic ellipsometry. The glass transition temperature is found to increase significantly with metal oxide loading. Copolymers with 0.0, 3.0, 7.7, 11.5, and 20.2% HEMA units experienced 6, 8, 22, 37, and 46 °C increases in T g, respectively. Changes in T g at low HEMA compositions fit the Fox–Loshaek model for cross-linking phenomena, which, along with a dissolution study on these materials, suggests that VPI is cross-linking the PS-r-PHEMA polymer. This study demonstrates that VPI is useful for altering the thermophysical and thermochemical properties of polymer materials, with applicability to many form factors including thin films, coatings, membranes, foams, fibers, and fabrics.

Polyethylene furanoate (PEF) is a bioplastic that can potentially replace its fossil-fuel counterpart, polyethylene terephthalate (PET), to reduce greenhouse gas (GHG) emissions. A life-cycle GHG, water, and fossil-fuel consumption analysis is conducted for a potential bioplastic alternative for a fossil-based PET resin, or PEF on a kg-resin basis. PEF is assumed to be produced from a lignocellulosic feedstock (i.e., wheat straw) via furanics conversion reactions through three different pathways. The system boundary includes cradle-to-gate processes including feedstock farming, pretreatment, hydrolysis, conversion into furanics, recovery, polymerization into PEF, and on-site combined heat and power (CHP) generation. While electricity export from the CHP plant is assumed to displace the U. S. grid electricity, other coproducts of PEF are assumed to distribute the emissions and energy burdens on a mass basis. The results showed that all three PEF routes achieved significant GHG reduction relative to its fossil-based counterpart (i.e., PET): 134, 139, and 163% reduction for routes 1, 2, and 3, respectively. While fossil-fuel consumptions for all three pathways were also significantly reduced (i.e., 79, 57, and 53% reduction for routes 1, 2, and 3), water consumptions for routes 1 and 2 were increased by 168 and 79%, respectively, while route 3 only achieved reduction (by 77%) relative to fossil-PET. Different sensitivity analyses were conducted, and the results showed that coproduct allocation methods and wheat straw management assumption were the most important. A preliminary analysis on the farmland area and cost required to reduce unit mass of GHGs using PEF to replace PET is also conducted, showing a promising result for both metrics: (i) 3 metric tons of GHGs reduced/ha for all three PEF pathways and (ii) affordable cost of GHG abatement for routes 1 and 2, while route 3 even generated profits.