Fractal approach to the critical filler volume fraction of an electrically conductive polymer composite

Zhang, Ming Qiu; Xu, Jia; Zeng, Han; Huo, Qun; Zhang, Zhi Yi; Yun, Feng Chun; Friedrich, K.

doi:10.1007/bf00361501

Cited by 60 publications

(25 citation statements)

References 11 publications

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“…This is strong evidence of a percolation type transport mechanism characterized by a threshold crystallinity, with any further increase in the degree of crystallinity beyond 3 min having little or no impact on the mobility of carriers, akin to a percolation threshold in carbon black/polymer systems. [ 24 ] We suggest that the percolation pathway in the P3HT thin fi lms is formed by regions of varying conductivity, attributed to the presence of three distinct phases, possibly varying in their crystalline order. Based on the analysis of Holdcroft et al [ 38 ] we suggest that ultrasonic irradiation of solutions leads to a continuous transition from a disordered (for fi lms obtained from pristine solutions) to an ordered state, with both incorporating fractions of an intermediate quasi-ordered phase.…”

Section: Discussionmentioning

confidence: 99%

Tunable Crystallinity in Regioregular Poly(3‐Hexylthiophene) Thin Films and Its Impact on Field Effect Mobility

Aiyar

Hong

Nambiar

et al. 2011

Adv Funct Materials

119

228

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The properties of poly(alkylthiophenes) in solution are found to have a profound impact on the self assembly process and thus the microstructural and electrical properties of the resultant thin films. Ordered supramolecular precursors can be formed in regioregular poly(3‐hexylthiophene) (P3HT) solutions through the application of low intensity ultrasound. These precursors survive the casting process, resulting in a dramatic increase in the degree of crystallinity of the thin films obtained by spin coating. The crystallinity of the films is tunable, with a continuous evolution of mesoscale structures observed as a function of ultrasonic irradiation time. The photophysical properties of P3HT in solution as well in the solid state suggest that the application of ultrasound leads to a π stacking induced molecular aggregation resulting in field effect mobilities as high as 0.03 cm2 V−1 s−1. A multiphase morphology, comprising short quasi‐ordered and larger, ordered nanofibrils embedded in a disordered amorphous phase is formed as a result of irradiation for at least 1 min. Two distinct regions of charge transport are identified, characterized by an initial sharp increase in the field effect mobility by two orders of magnitude due to an increase in crystallinity up to the percolation limit, followed by a gradual saturation where the mobility becomes independent of the thin film microstructure.

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Section: Discussionmentioning

confidence: 99%

Tunable Crystallinity in Regioregular Poly(3‐Hexylthiophene) Thin Films and Its Impact on Field Effect Mobility

Aiyar

Hong

Nambiar

et al. 2011

Adv Funct Materials

119

228

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show abstract

“…In comparison with the composite filled by untreated CB, the composites' performance exhibits different tendencies of variation with treatment methods: (1) there is a remarkable increase in RT , but a decrease in M due to nitric acid; (2) there is a slight decrease in RT and increase in M due to titanate coupling agents of TC-114 and TM-27; and (3) both RT and M increase due to titanate coupling agent of TC-931. To reveal the mechanisms involved, ESCA (electron spectroscopy for chemical analysis) was applied to examine CB surface.…”

Section: Effect Of Cb Treatmentsmentioning

confidence: 91%

“…These results confirm that M is directly related to composite conductivity, or in other words, filler arrangement plays a leading role in controlling ultimate material property. 2 Usually, shearing could break CB agglomerates into a few larger fragments at the early stage of dispersion, which is followed by a gradual erosion of small aggregates being continuously detached from the outer surface of these fragments throughout the whole dispersion process. 20 As a result, shear mixing led to (1) smaller size of CB, enhancing the formation probability of conductive networks in favor of lowering composite resistivity, compared with larger particles in the case of the same filler content and arrangement 2 ; (2) higher dispersion homogeneity of CB, isolating more fillers from one another and decreasing the apparent melt viscosity; and (3) worse conduction performance of CB due to structure breakdown.…”

Section: Figurementioning

confidence: 99%

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Carbon-black-filled polyolefine as a positive temperature coefficient material: Effect of composition, processing, and filler treatment

Yu¹,

Zhang²,

Zeng³

1998

J. Appl. Polym. Sci.

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ABSTRACT:Polymer-based positive temperature coefficient (PTC) composites are of special interest because they have great potential in temperature-sensitive devices. To obtain a reproducible PTC composite with acceptable PTC intensity, effect of conductive filler content, processing conditions and filler treatment with nitric acid, and titanate coupling agents on room temperature resistivity and PTC intensity of carbon-blackfilled low-density polyethylene composites have been described and discussed herein. The results showed that filler arrangement is a key factor influencing the ultimate material performance, which can be tailored in various ways.

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“…Usually decreasing filler size leads to a decreased percolation threshold because interparticle contacts increase with an increase in the amount of the particles. 9 Most studies to date have focused on the characterization of such polymer composites. Although there has been some earlier work on incorporation of silver nanoparticles in an epoxy matrix, 10 the present study considers an in situ reduction approach.…”

Section: Introductionmentioning

confidence: 99%

Development of a novel polymer–metal nanocomposite obtained through the route of in situ reduction for integral capacitor application

Pothukuchi

Wong

2004

J of Applied Polymer Sci

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ABSTRACT:Metal nanoparticles exhibit a number of interesting characteristics, including unique physical, chemical, optical, magnetic, and electric properties. Numerous investigations have exploited their properties in a readily usable form by incorporating them into polymers. The current focus of interest is the behavior of such polymer nanocomposites near the percolation loading levels of the metal nanoparticles. This material is particularly suitable for the new integral passive technology. Discrete capacitors are used in many applications, such as noise suppression, filtering, tuning, decoupling, bypassing, termination, and frequency determination, and they occupy a substantial amount of surface area on a substrate. Thus there are limitations in the number of capacitors that can be placed around the chip. Integral passive components are gradually replacing discrete components because of the inherent advantages of improved electrical performance, increased real estate on the printed wiring board, miniaturization of interconnect distance, reduced processing costs, and efficient electronics packaging. For integral capacitors, polymer composite material has emerged as a potential candidate because it meets the requirements of low processing temperature and reasonably high dielectric constant. Yang and Wong, whose patent was filed in 2001, demonstrated novel integral passive component materials with extraordinarily high dielectric constants (K Ͼ 1000) and high reliability performance. These materials are characterized by high dielectric constant based on the mechanism of interfacial polarization, although they need precision filler concentration control. The current study overcomes this drawback and produces the composite through an in situ reduction in an epoxy matrix. Material characterization was done through TEM, SEM, X-ray analysis, and energy-dispersive analysis for X rays.

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Fractal approach to the critical filler volume fraction of an electrically conductive polymer composite

Cited by 60 publications

References 11 publications

Tunable Crystallinity in Regioregular Poly(3‐Hexylthiophene) Thin Films and Its Impact on Field Effect Mobility

Tunable Crystallinity in Regioregular Poly(3‐Hexylthiophene) Thin Films and Its Impact on Field Effect Mobility

Carbon-black-filled polyolefine as a positive temperature coefficient material: Effect of composition, processing, and filler treatment

Development of a novel polymer–metal nanocomposite obtained through the route of in situ reduction for integral capacitor application

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