Fabrication of micropillars on nanocellulose films using a roll-to-roll nanoimprinting method

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Abstract

This paper presents a simple method to modify biobased nanocellulosic films with thermal roll-to-roll nanoimprinting lithography (R2RNIL) to produce microstructured films. In the NIL process a patterned roll and an elastic backing roll are pressed against each other at elevated temperatures, and the pattern is replicated onto the film structure. Here we demonstrate the fabrication of patterned nanocellulosic films prepared using mechanically disintegrated cellulose nanofibrils (CNF) and TEMPO-oxidised cellulose nanofibrils (TEMPOCNF). Although both CNF films are brittle and nanocellulosic material itself is not thermoplastic with a clear softening point, it was shown that the mechanical patterning of both CNF films was possible. Imprinted pillar structures with a width of 7.5 µmand a height of 1.5 µmwere achieved and both of the patterned CNF films showed a clear optical effect. The patterns are formed probably due to the compressibility of the CNF films and due to the film softening effect brought about by sorbitol, which is a commonly utilised softener for biopolymer films. In addition, the polyvinyl alcohol (PVA) used as a strength additive in the case of the films prepared using TEMPOoxidised CNF possesses a thermoplastic feature. Distinct temperature dependency was observed with both films above 70 °C. The height of the pillars increased almost linearly up to 155 °C with a constant pressure of 8 MPa. The temperature increase seems to improve the replication of the pillar shape. Simultaneously the nanoimprinting process smoothed the film surface roughness. Recovery and relaxation properties of the NIL-patterned CNF films were studied after one week. Height changes were as high as 36% for CNF film and 20% for TEMPO-CNF film.
Original languageEnglish
Pages (from-to)1-6
JournalMicroelectronic Engineering
Volume163
DOIs
Publication statusPublished - 2016
MoE publication typeA1 Journal article-refereed

Fingerprint

Cellulose films
Fabrication
cellulose
fabrication
Cellulose
Thermoplastics
oxidized cellulose
Polyvinyl Alcohol
Biopolymers
Sorbitol
Polyvinyl alcohols
softening
Compressibility
Temperature
Lithography
Surface roughness
brittle materials
polyvinyl alcohol
Recovery
biopolymers

Keywords

  • nanoimprinting
  • hot embossing
  • roll-to-roll
  • R2RNIL
  • surface modification
  • cellulose nanofibrils
  • CNF
  • optical effect

Cite this

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title = "Fabrication of micropillars on nanocellulose films using a roll-to-roll nanoimprinting method",
abstract = "This paper presents a simple method to modify biobased nanocellulosic films with thermal roll-to-roll nanoimprinting lithography (R2RNIL) to produce microstructured films. In the NIL process a patterned roll and an elastic backing roll are pressed against each other at elevated temperatures, and the pattern is replicated onto the film structure. Here we demonstrate the fabrication of patterned nanocellulosic films prepared using mechanically disintegrated cellulose nanofibrils (CNF) and TEMPO-oxidised cellulose nanofibrils (TEMPOCNF). Although both CNF films are brittle and nanocellulosic material itself is not thermoplastic with a clear softening point, it was shown that the mechanical patterning of both CNF films was possible. Imprinted pillar structures with a width of 7.5 µmand a height of 1.5 µmwere achieved and both of the patterned CNF films showed a clear optical effect. The patterns are formed probably due to the compressibility of the CNF films and due to the film softening effect brought about by sorbitol, which is a commonly utilised softener for biopolymer films. In addition, the polyvinyl alcohol (PVA) used as a strength additive in the case of the films prepared using TEMPOoxidised CNF possesses a thermoplastic feature. Distinct temperature dependency was observed with both films above 70 °C. The height of the pillars increased almost linearly up to 155 °C with a constant pressure of 8 MPa. The temperature increase seems to improve the replication of the pillar shape. Simultaneously the nanoimprinting process smoothed the film surface roughness. Recovery and relaxation properties of the NIL-patterned CNF films were studied after one week. Height changes were as high as 36{\%} for CNF film and 20{\%} for TEMPO-CNF film.",
keywords = "nanoimprinting, hot embossing, roll-to-roll, R2RNIL, surface modification, cellulose nanofibrils, CNF, optical effect",
author = "Tapio M{\"a}kel{\"a} and Markku Kainlauri and Pia Willberg-Keyril{\"a}inen and Tekla Tammelin and Ulla Forsstr{\"o}m",
note = "Project code: 603519",
year = "2016",
doi = "10.1016/j.mee.2016.05.023",
language = "English",
volume = "163",
pages = "1--6",
journal = "Microelectronic Engineering",
issn = "0167-9317",
publisher = "Elsevier",

}

TY - JOUR

T1 - Fabrication of micropillars on nanocellulose films using a roll-to-roll nanoimprinting method

AU - Mäkelä, Tapio

AU - Kainlauri, Markku

AU - Willberg-Keyriläinen, Pia

AU - Tammelin, Tekla

AU - Forsström, Ulla

N1 - Project code: 603519

PY - 2016

Y1 - 2016

N2 - This paper presents a simple method to modify biobased nanocellulosic films with thermal roll-to-roll nanoimprinting lithography (R2RNIL) to produce microstructured films. In the NIL process a patterned roll and an elastic backing roll are pressed against each other at elevated temperatures, and the pattern is replicated onto the film structure. Here we demonstrate the fabrication of patterned nanocellulosic films prepared using mechanically disintegrated cellulose nanofibrils (CNF) and TEMPO-oxidised cellulose nanofibrils (TEMPOCNF). Although both CNF films are brittle and nanocellulosic material itself is not thermoplastic with a clear softening point, it was shown that the mechanical patterning of both CNF films was possible. Imprinted pillar structures with a width of 7.5 µmand a height of 1.5 µmwere achieved and both of the patterned CNF films showed a clear optical effect. The patterns are formed probably due to the compressibility of the CNF films and due to the film softening effect brought about by sorbitol, which is a commonly utilised softener for biopolymer films. In addition, the polyvinyl alcohol (PVA) used as a strength additive in the case of the films prepared using TEMPOoxidised CNF possesses a thermoplastic feature. Distinct temperature dependency was observed with both films above 70 °C. The height of the pillars increased almost linearly up to 155 °C with a constant pressure of 8 MPa. The temperature increase seems to improve the replication of the pillar shape. Simultaneously the nanoimprinting process smoothed the film surface roughness. Recovery and relaxation properties of the NIL-patterned CNF films were studied after one week. Height changes were as high as 36% for CNF film and 20% for TEMPO-CNF film.

AB - This paper presents a simple method to modify biobased nanocellulosic films with thermal roll-to-roll nanoimprinting lithography (R2RNIL) to produce microstructured films. In the NIL process a patterned roll and an elastic backing roll are pressed against each other at elevated temperatures, and the pattern is replicated onto the film structure. Here we demonstrate the fabrication of patterned nanocellulosic films prepared using mechanically disintegrated cellulose nanofibrils (CNF) and TEMPO-oxidised cellulose nanofibrils (TEMPOCNF). Although both CNF films are brittle and nanocellulosic material itself is not thermoplastic with a clear softening point, it was shown that the mechanical patterning of both CNF films was possible. Imprinted pillar structures with a width of 7.5 µmand a height of 1.5 µmwere achieved and both of the patterned CNF films showed a clear optical effect. The patterns are formed probably due to the compressibility of the CNF films and due to the film softening effect brought about by sorbitol, which is a commonly utilised softener for biopolymer films. In addition, the polyvinyl alcohol (PVA) used as a strength additive in the case of the films prepared using TEMPOoxidised CNF possesses a thermoplastic feature. Distinct temperature dependency was observed with both films above 70 °C. The height of the pillars increased almost linearly up to 155 °C with a constant pressure of 8 MPa. The temperature increase seems to improve the replication of the pillar shape. Simultaneously the nanoimprinting process smoothed the film surface roughness. Recovery and relaxation properties of the NIL-patterned CNF films were studied after one week. Height changes were as high as 36% for CNF film and 20% for TEMPO-CNF film.

KW - nanoimprinting

KW - hot embossing

KW - roll-to-roll

KW - R2RNIL

KW - surface modification

KW - cellulose nanofibrils

KW - CNF

KW - optical effect

U2 - 10.1016/j.mee.2016.05.023

DO - 10.1016/j.mee.2016.05.023

M3 - Article

VL - 163

SP - 1

EP - 6

JO - Microelectronic Engineering

JF - Microelectronic Engineering

SN - 0167-9317

ER -