Cellulose Nanofibril Films as Bioinspired Membranes: Capitalizing on Water Interactions: Dissertation

Minna Hakalahti

Research output: ThesisDissertationMonograph

Abstract

This work represents an effort to exploit the inherent features of nanoscaled cellulose as practical advantages in membrane materials. The approach was to systematically explore the behavior of 2,2,6,6-tetramethylpiperidine-1-oxyl radical oxidized cellulose nanofibrils (TEMPO CNF) with respect to water vapor sorption mechanisms and transport of water, to tune the inherent properties using facile strategies and to expose the materials to performance testing. Surface-sensitive methods were used for revealing molecular scale phenomena directly at interfaces, whereas bulk methods were used to demonstrate their significance in macroscopic scale. Films made from TEMP O CNF were in the main role, complemented by synthetic polymers to introduce new performance features with significance for membrane materials. Water vapor sorption of TEMPO CNF thin films was studied by precise surface-sensitive analytical methods, i.e. quartz crystal microbalance with dissipation monitoring and spectroscopic ellipsometry, and combined with classical physicochemical models. It was established that water vapor sorption into TEMPO CNF thin films occurs through distinct underlying mechanisms: specific sorption below 10% RH, association of Flory-Huggins population of molecules with the films at 10-75% RH and clustering of water molecules above 75% RH. Kinetic parameters defining the transport of water molecules in the TEMPO CNF film structure were determined. The results showed that diffusion of water vapor could be used as a probing tool for elucidating structural details of moisture-responsive materials in the presence of water. Bulk and interfacial chemical modification approaches were applied. Enhancement of wet strength of TEMPO CNF films was achieved by crosslinking, whereby inherent characteristics, such as hydrophilicity, were not compromised. The water stable structure was suitable for further functionalization with a thermoresponsive polymer, poly(NIPAM). Covering mere 8% of the surface with poly(NIPAM) caused drastic changes in the performance of the TEMPO CNF film, as the increment in slope of relative water permeance around the lower critical solution temperature of poly(NIPAM) increased from 18% to 100%, showcasing the efficiency of the interfacial modification approach. CNF films were also subjected to performance testing in tetrahydrofuran and n-hexane, whereby their suitability for organic solvent nanofiltration was demonstrated. This thesis furthers the fundamental understanding of water interactions of cellulosic nanomaterials and other complex moisture-sensitive structures in the biomaterial genre. It also proposes concrete means to tune selected material properties toward desired environments and effects. In the view of this thesis, inherent structure-derived properties are the key for achieving performance features that will carry future biomaterials development beyond conventional
applications.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • Aalto University
Supervisors/Advisors
  • Kontturi, Eero, Supervisor, External person
  • Tammelin, Tekla, Advisor
Award date23 Feb 2018
Place of PublicationHelsinki
Publisher
Print ISBNs978-952-60-7856-4, 978-951-38-8619-6
Electronic ISBNs978-952-60-7857-1, 978-951-38-8618-9
Publication statusPublished - 23 Feb 2018
MoE publication typeG4 Doctoral dissertation (monograph)

Fingerprint

Cellulose films
oxidized cellulose
Membranes
Steam
Water
Sorption
Biocompatible Materials
Molecules
Polymers
Moisture
Thin films
Nanofiltration
Spectroscopic ellipsometry
Quartz crystal microbalances
Chemical modification
Hydrophilicity
Testing
Kinetic parameters
Nanostructured materials
Cellulose

Keywords

  • cellulose nanofibrils
  • water interactions
  • films
  • membranes
  • surface-sensitive techniques

Cite this

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title = "Cellulose Nanofibril Films as Bioinspired Membranes: Capitalizing on Water Interactions: Dissertation",
abstract = "This work represents an effort to exploit the inherent features of nanoscaled cellulose as practical advantages in membrane materials. The approach was to systematically explore the behavior of 2,2,6,6-tetramethylpiperidine-1-oxyl radical oxidized cellulose nanofibrils (TEMPO CNF) with respect to water vapor sorption mechanisms and transport of water, to tune the inherent properties using facile strategies and to expose the materials to performance testing. Surface-sensitive methods were used for revealing molecular scale phenomena directly at interfaces, whereas bulk methods were used to demonstrate their significance in macroscopic scale. Films made from TEMP O CNF were in the main role, complemented by synthetic polymers to introduce new performance features with significance for membrane materials. Water vapor sorption of TEMPO CNF thin films was studied by precise surface-sensitive analytical methods, i.e. quartz crystal microbalance with dissipation monitoring and spectroscopic ellipsometry, and combined with classical physicochemical models. It was established that water vapor sorption into TEMPO CNF thin films occurs through distinct underlying mechanisms: specific sorption below 10{\%} RH, association of Flory-Huggins population of molecules with the films at 10-75{\%} RH and clustering of water molecules above 75{\%} RH. Kinetic parameters defining the transport of water molecules in the TEMPO CNF film structure were determined. The results showed that diffusion of water vapor could be used as a probing tool for elucidating structural details of moisture-responsive materials in the presence of water. Bulk and interfacial chemical modification approaches were applied. Enhancement of wet strength of TEMPO CNF films was achieved by crosslinking, whereby inherent characteristics, such as hydrophilicity, were not compromised. The water stable structure was suitable for further functionalization with a thermoresponsive polymer, poly(NIPAM). Covering mere 8{\%} of the surface with poly(NIPAM) caused drastic changes in the performance of the TEMPO CNF film, as the increment in slope of relative water permeance around the lower critical solution temperature of poly(NIPAM) increased from 18{\%} to 100{\%}, showcasing the efficiency of the interfacial modification approach. CNF films were also subjected to performance testing in tetrahydrofuran and n-hexane, whereby their suitability for organic solvent nanofiltration was demonstrated. This thesis furthers the fundamental understanding of water interactions of cellulosic nanomaterials and other complex moisture-sensitive structures in the biomaterial genre. It also proposes concrete means to tune selected material properties toward desired environments and effects. In the view of this thesis, inherent structure-derived properties are the key for achieving performance features that will carry future biomaterials development beyond conventionalapplications.",
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Cellulose Nanofibril Films as Bioinspired Membranes : Capitalizing on Water Interactions: Dissertation. / Hakalahti, Minna.

Helsinki : Aalto University, 2018. 164 p.

Research output: ThesisDissertationMonograph

TY - THES

T1 - Cellulose Nanofibril Films as Bioinspired Membranes

T2 - Capitalizing on Water Interactions: Dissertation

AU - Hakalahti, Minna

PY - 2018/2/23

Y1 - 2018/2/23

N2 - This work represents an effort to exploit the inherent features of nanoscaled cellulose as practical advantages in membrane materials. The approach was to systematically explore the behavior of 2,2,6,6-tetramethylpiperidine-1-oxyl radical oxidized cellulose nanofibrils (TEMPO CNF) with respect to water vapor sorption mechanisms and transport of water, to tune the inherent properties using facile strategies and to expose the materials to performance testing. Surface-sensitive methods were used for revealing molecular scale phenomena directly at interfaces, whereas bulk methods were used to demonstrate their significance in macroscopic scale. Films made from TEMP O CNF were in the main role, complemented by synthetic polymers to introduce new performance features with significance for membrane materials. Water vapor sorption of TEMPO CNF thin films was studied by precise surface-sensitive analytical methods, i.e. quartz crystal microbalance with dissipation monitoring and spectroscopic ellipsometry, and combined with classical physicochemical models. It was established that water vapor sorption into TEMPO CNF thin films occurs through distinct underlying mechanisms: specific sorption below 10% RH, association of Flory-Huggins population of molecules with the films at 10-75% RH and clustering of water molecules above 75% RH. Kinetic parameters defining the transport of water molecules in the TEMPO CNF film structure were determined. The results showed that diffusion of water vapor could be used as a probing tool for elucidating structural details of moisture-responsive materials in the presence of water. Bulk and interfacial chemical modification approaches were applied. Enhancement of wet strength of TEMPO CNF films was achieved by crosslinking, whereby inherent characteristics, such as hydrophilicity, were not compromised. The water stable structure was suitable for further functionalization with a thermoresponsive polymer, poly(NIPAM). Covering mere 8% of the surface with poly(NIPAM) caused drastic changes in the performance of the TEMPO CNF film, as the increment in slope of relative water permeance around the lower critical solution temperature of poly(NIPAM) increased from 18% to 100%, showcasing the efficiency of the interfacial modification approach. CNF films were also subjected to performance testing in tetrahydrofuran and n-hexane, whereby their suitability for organic solvent nanofiltration was demonstrated. This thesis furthers the fundamental understanding of water interactions of cellulosic nanomaterials and other complex moisture-sensitive structures in the biomaterial genre. It also proposes concrete means to tune selected material properties toward desired environments and effects. In the view of this thesis, inherent structure-derived properties are the key for achieving performance features that will carry future biomaterials development beyond conventionalapplications.

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KW - cellulose nanofibrils

KW - water interactions

KW - films

KW - membranes

KW - surface-sensitive techniques

M3 - Dissertation

SN - 978-952-60-7856-4

SN - 978-951-38-8619-6

T3 - VTT Science

PB - Aalto University

CY - Helsinki

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