Enhanced Thermal Conductivity of Liquid Crystalline Epoxy Resin using Controlled Linear Polymerization

Abstract

A powerful strategy to enhance the thermal conductivity of liquid crystalline epoxy resin (LCER) by simply replacing the conventional amine cross-linker with a cationic initiator was developed. The cationic initiator linearly wove the epoxy groups tethered on the microscopically aligned liquid crystal mesogens, resulting in freezing of the ordered LC microstructures even after curing. Owing to the reduced phonon scattering during heat transport through the ordered LC structure, a dramatic improvement in the thermal conductivity of neat cation-cured LCER was achieved to give a value ∼141% (i.e., 0.48 W/mK) higher than that of the amorphous amine-cured LCER. In addition, at the same composite volume fraction in the presence of a 2-D boron nitride filler, an approximately 130% higher thermal conductivity (maximum ∼23 W/mK at 60 vol %) was observed. The nanoarchitecture effect of the ordered LCER on the thermal conductivity was then examined by a systematic investigation using differential scanning calorimetry, polarized optical microscopy, X-ray diffraction, and thermal conductivity measurements. The linear polymerization of LCER can therefore be considered a practical strategy to enable the cost-efficient mass production of heat-dissipating materials, due to its high efficiency and simple process without the requirement for complex equipment.

Thermal Conductivity and Cure Kinetics of Epoxy-Boron Nitride Composites—A Review

“…There are still two sets of data in particular which stand out from the rest in Figure 7, and which fall between the upper and intermediate trend lines. Both sets of data, indicated by grey-blue and green filled circles, are from Islam et al [95], and correspond to composites in which the matrix was a liquid crystalline epoxy resin. These results will be discussed in more detail below.…”

“… Thermal conductivity of epoxy-BN composites as a function of the BN content by weight. Data taken from references [ 54 , 57 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , …”

Recent Advances in Thermal Interface Materials

“…With continuingly increasing power of electronic devices, the amount of heat generated is sharply increasing. [1][2][3][4][5] Owing to roughness in morphology, just a small fraction of the apparent surface area will have an actual contact when two solid surfaces are joined. [6][7][8][9][10] The rest of the area will be separated by an air-filled gap, and since the thermal conductivity of air (0.026 W/mK) is about four orders of magnitude lower than that of metals, heat transfer across the interface through air is negligible.…”

Self‐healable and reprocessible liquid crystalline elastomer and its highly thermal conductive composites by incorporating graphene via in‐situ polymerization

“…SHLCE exhibited sharp peaks at 2θ = 19.3, 20.5 and 22.7° superposed on a broad amorphous peak. The broad peak (2θ = 15–30°) related to the nematic phase formed by the orientation of the mesogenic group 21,55 . However, the sharp peak general means the presence of the crystal structure.…”

“…The broad peak (2θ = 15-30 ) related to the nematic phase formed by the orientation of the mesogenic group. 21,55 However, the sharp peak general means the presence of the crystal structure. The rigid biphenyl structure would make the molecular chain highly ordered and promote the formation of ordered domains in the cross-linked network structure.…”