Display Light Guide Swelling Due to Moisture Absorption

Cousins, A. K.; Thiel, George H.; Wolak, E.; Limaye, Geeta; Tiku, Sanjay

doi:10.1115/1.4037971

Cited by 2 publications

(1 citation statement)

References 7 publications

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“…Commercial display products are becoming thinner, and their display areas are becoming larger, , leading to a high demand for larger and thinner PMMA-based products. However, several problems have been reported for PMMA manufactured in large areas and thin forms, such as distortion at elevated temperatures and deformation upon exposure to moisture. , These problems frequently lead to a decrease in the light transmittance of PMMA, negatively impacting its utility for optical applications. Thus, enhancing the heat resistance and reducing the moisture absorption of PMMA are required to address these problems.…”

Section: Introductionmentioning

confidence: 99%

Development of Poly(methyl methacrylate)-Based Copolymers with Improved Heat Resistance and Reduced Moisture Absorption

et al. 2019

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Poly(methyl methacrylate) (PMMA) is widely used as a transparent material for optical applications, owing to its high light transmittance. However, it exhibits poor heat resistance and high moisture absorption, leading to distortion and deformation upon exposure to elevated temperatures and/or moisture. These structural changes decrease the transparency of PMMA, critically limiting its applicability. In this study, we synthesized poly(methyl methacrylate-co-styrene-co-acrylamide) (PMSAm) as a reference polymer and introduced one of four different comonomers [N-phenylmaleimide (PMI), N-cyclohexylmaleimide (CHMI), allyltrimethylsilane (ATMS), or 2,2,2-trifluoroethyl methacrylate (TF)] as a means to improve heat resistance and reduce moisture absorption. Four series of PMMA-based random copolymers (PMSAm–PMI, PMSAm–CHMI, PMSAm–ATMS, and PMSAm–TF) were synthesized by conventional thermal radical polymerization. All of the polymers synthesized exhibited improved heat resistance, with PMSAm–CHMI exhibiting the highest glass transition temperature (T g = 122.54 °C) and 5% weight loss thermal decomposition temperature (T 5d = 343.40 °C) as well as the lowest thermal expansion coefficient (90.3 μm m–1 °C–1). The highest hydrophobicity was exhibited by PMSAm–TF, with a water contact angle of 78.9°, indicating higher hydrophobicity compared to that of pure PMMA (69.4°). More importantly, high transparency (∼90%) was exhibited by all of the synthesized polymers. Thus, our copolymerization strategy successfully addresses the limitations, i.e., low heat resistance and high moisture absorption, of conventional PMMA-based materials.

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