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Tailored adhesion of PISA-latexes for cellulose modification and new materials
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. (Malmström Group)ORCID iD: 0000-0002-9572-6888
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is focused on applying modification chemistry to already known cellulosic substrates from wood (i.e. cellulose nanofibrils, CNFs, and cellulose nanocrystals, CNCs). The modification is needed to overcome the drawbacks with the nanocellulosics alone, such as sensitivity to water (hydrophilicity) and the brittle material properties (however great stiffness). The first aim is to incorporate nanocellulosics into hydrophobic degradable materials of poly(ε-caprolactone) (PCL), resulting in aggregation if not modified. The challenge is to reach high fraction of nanocellulosics, whilst maintaining the flexibility of PCL and improving the properties of the resulting nanocomposite with the corresponding stiffness of the nanocellulosics. The second aim is to increase toughness and strain-at-break for nanocomposite materials of CNF-networks, to increase the plastic deformation equivalent of fossil-based polymeric materials such as polypropylene (PP). Aiming to achieve these goals, the thesis also includes new synthetic strategies of tailored-made set of block copolymers as modifying components. The modifying components, were synthesised by surfactant-free emulsion polymerisation and polymerisation induced self-assembly (PISA), so called PISA-latexes.

Two types of cationic polyelectrolytes, (poly(2-dimethylaminoethy methacrylate) (PDMAEMA) and poly(N-[3-(dimethylamino)propyl] methacrylamide (PDMAPMA)), being the corona of the latex, were synthesised. Followed by chain-extension with different hydrophobic monomers such as methyl methacrylate and butyl methacrylate, making up the core polymer of the resulting PISA-latex. The cationic PISA-latexes show narrow size distributions and the glass transition (Tg) of the core polymer can be varied between -40 °C to 150 °C. The PISA-latexes show strong adhesion to silica and cellulose surfaces as assessed by quartz crystal microbalance (QCM-D). Results also indicate that latexes with Tg below room temperature, considered soft, behave different in the wet state than latexes with Tg above room temperature, considered rigid. The softer latexes form clusters (visualised by imaging with microscopy and atomic force measurements (AFM)) and undergo film formation in the wet state. The latter, shown by colloidal probe measurements using AFM resulting in very large work of adhesion and pull-off forces.

The PISA-latexes compatibilize CNCs and different CNFs with PCL as a matrix polymer, observed by a small increase in stiffness for the final nanocomposites, however not at a level expected by rule-of-mixtures. The promising wet feeding technique results in large increase in stiffness but maintain PCL’s flexibility, above 200% strain-at-break, which is rarely observed for CNF-reinforced nanocomposites. The, in this case, rigid latex facilitate the dispersion of CNFs in the matrix without aggregation, until finally coalescing after processing and possibly giving rise to improved adhesion between CNF and the latex in the matrix, indicated by rheology measurements. Lastly, new nanocomposite films consisting of 75wt% CNF and 25wt% of PISA-latexes were produced and evaluated. The results show that CNF and rigid 100 nm sized PISA-latex, with PMMA core, gives a very tough double network, with strain-at-break above 28%, stiffness of 3.5 GPa and a strength of 110 MPa. These are impressive properties compared to commonly used fossil-based plastic materials.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2019. , p. 128
Series
TRITA-CBH-FOU ; 2019:7
Keywords [en]
PISA, latex, RAFT, Cellulose Nanofibrils, Cellulose Nanocrystals, Nanocomposites
National Category
Polymer Chemistry
Research subject
Fibre and Polymer Science
Identifiers
URN: urn:nbn:se:kth:diva-241463ISBN: 978-91-7873-086-5 (electronic)OAI: oai:DiVA.org:kth-241463DiVA, id: diva2:1281533
Public defence
2019-02-22, Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20190123

Available from: 2019-01-23 Created: 2019-01-22 Last updated: 2019-05-20Bibliographically approved
List of papers
1. Soft and rigid core latex nanoparticles prepared by RAFT-mediated surfactant-free emulsion polymerization for cellulose modification-a comparative study
Open this publication in new window or tab >>Soft and rigid core latex nanoparticles prepared by RAFT-mediated surfactant-free emulsion polymerization for cellulose modification-a comparative study
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2017 (English)In: Polymer Chemistry, ISSN 1759-9954, E-ISSN 1759-9962, Vol. 8, no 6, p. 1061-1073Article in journal (Refereed) Published
Abstract [en]

Latex nanoparticles comprising cationically charged coronas and hydrophobic cores with different glass transition temperatures (Tg) have been prepared by surfactant-free, RAFT-mediated emulsion polymerization, where the particles form through a polymerization-induced self-assembly (PISA) type mechanism. Poly(2-dimethylaminoethyl methacrylate-co-methacrylic acid) (P(DMAEMA-co-MAA)) was utilized as a hydrophilic macroRAFT agent for the polymerization of methyl methacrylate (MMA) or n-butyl methacrylate (nBMA), respectively, resulting in two different latexes, with either a core of high (PMMA) or low (PnBMA) Tg polymer. By varying the molar mass of the hydrophobic block, latexes of different sizes were obtained (DHca. 40-120 nm). The adsorption of the latexes to cellulose model surfaces and cellulose nanofibrils (CNF) was studied using quartz crystal microbalance with dissipation monitoring (QCM-D). The surfaces with adsorbed PnBMA latexes yielded hydrophobic surfaces both before and after annealing, whereas surfaces with adsorbed PMMA latex became hydrophobic only after annealing, clearly showing the influence of the Tg of the core. The latexes were also used to modify macroscopic cellulose in the form of filter papers. Similar to the CNF surfaces, no annealing was required to achieve hydrophobic surfaces with PnBMA latexes. Finally, nanocomposites of CNF and the polymer nanoparticles were prepared through a one-pot mixing procedure. It was found that the largest synthesized PMMA latex (120 nm) facilitated a more strainable CNF network at 50% relative humidity, with a nearly 200% increase in strain at break compared to the neat CNF reference film as well as to the composite films with PnBMA latexes or to the smaller sized PMMA latexes. This difference was attributed to the spherical shape and rigidity of the large PMMA latex nanoparticles during composite formation. This highly interesting result should indeed be considered in the future design of novel biocomposites.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2017
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-208109 (URN)10.1039/c6py01904h (DOI)000395539800012 ()2-s2.0-85011827572 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20170607

Available from: 2017-06-07 Created: 2017-06-07 Last updated: 2019-01-23Bibliographically approved
2. Tailoring adhesion of anionic surfaces using cationic PISA-latexes – towards tough nanocellulose materials in the wet state
Open this publication in new window or tab >>Tailoring adhesion of anionic surfaces using cationic PISA-latexes – towards tough nanocellulose materials in the wet state
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2019 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, p. 4287-4302Article in journal (Refereed) Published
Abstract [en]

Cationic latexes with Tgs ranging between −40 °C and 120 °C were synthesised using n-butyl acrylate (BA) and/or methyl methacrylate (MMA) as the core polymers. Reversible addition–fragmentation chain transfer (RAFT) combined with polymerisation-induced self-assembly (PISA) allowed for in situ chain-extension of a cationic macromolecular RAFT agent (macroRAFT) of poly(N-[3-(dimethylamino)propyl] methacrylamide) (PDMAPMA), used as stabiliser in so-called surfactant-free emulsion polymerisation. The resulting narrowly distributed nanosized latexes adsorbed readily onto silica surfaces and to model surfaces of cellulose nanofibrils, as demonstrated by quartz crystal microbalance with dissipation monitoring (QCM-D) measurements. Adsorption to anionic surfaces increased when increasing ionic strength to 10 mM, indicating the influence of the polyelectrolyte effect exerted by the corona. The polyelectrolyte corona affected the interactions in the wet state, the stability of the latex and re-dispersibility after drying. The QCM-D measurements showed that a lower Tg of the core results in a more strongly interacting adsorbed layer at the solid–liquid interface, despite a comparable adsorbed mass, indicating structural differences of the investigated latexes in the wet state. The two latexes with Tg below room temperature (i.e. PBATg-40 and P(BA-co-MMA)Tg3) exhibited film formation in the wet state, as shown by AFM colloidal probe measurements. It was observed that P(BA-co-MMA)Tg3 latex resulted in the largest pull-off force, above 200 m Nm−1 after 120 s in contact. The strongest wet adhesion was achieved with PDMAPMA-stabilized latexes soft enough to allow for interparticle diffusion of polymer chains, and stiff enough to create a strong adhesive joint. Fundamental understanding of interfacial properties of latexes and cellulose enables controlled and predictive strategies to produce strong and tough materials with high nanocellulose content, both in the wet and dry state.

National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-241447 (URN)10.1039/C8NR08057G (DOI)000465410200012 ()2-s2.0-85062644682 (Scopus ID)
Note

QC 20190123

Available from: 2019-01-22 Created: 2019-01-22 Last updated: 2019-05-29Bibliographically approved
3. Polycaprolactone Nanocomposites Reinforced with Cellulose Nanocrystals Surface-Modified via Covalent Grafting or Physisorption: A Comparative Study
Open this publication in new window or tab >>Polycaprolactone Nanocomposites Reinforced with Cellulose Nanocrystals Surface-Modified via Covalent Grafting or Physisorption: A Comparative Study
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2017 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 40, p. 35305-35318Article in journal (Refereed) Published
Abstract [en]

In the present work, cellulose nanocrystals (CNCs) have been surface-modified either via covalent grafting or through physisorption of poly(n-butyl methacrylate) (PBMA) and employed as reinforcement in PCL. Covalent grafting was achieved by surface-initiated atom transfer radical polymerization (SI-ATRP). Two approaches were utilized for the physisorption: using either micelles of poly(dimethyl aminoethyl methacrylate)-block-poly(n-butyl methacrylate) (PDMAEMA-b-PBMA) or latex nanoparticles of poly(dimethyl aminoethyl methacrylate-co-methacrylic acid)-block-poly(n-butyl methacrylate) (P(DMAEMA-co-MAA)-b-PBMA). Block copolymers (PDMAEMA-b-PBMA)s were obtained by ATRP and subsequently micellized. Latex nanoparticles were produced via reversible addition-fragmentation chain-transfer (RAFT) mediated surfactant-free emulsion polymerization, employing polymer-induced self-assembly (PISA) for the particle formation. For a reliable comparison, the amounts of micelles/latex particles adsorbed and the amount of polymer grafted onto the CNCs were kept similar. Two different chain lengths of PBMA were targeted, below and above the critical molecular weight for chain entanglement of PBMA (M-n,M-c similar to 56 000 g mo1(-1)). Poly(epsilon-caprolactone) (PCL) nanocomposites reinforced with unmodified and modified CNCs in different weight percentages (0.5, 1, and 3 wt %) were prepared via melt extrusion. The resulting composites were evaluated by UV-vis, scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and tensile testing. All materials resulted in higher transparency, greater thermal stability, and stronger mechanical properties than unfilled PCL and nanocomposites containing unmodified CNCs. The degradation temperature of PCL reinforced with grafted CNCs was higher than that of micelle-modified CNCs, and the latter was higher than that of latex-adsorbed CNCs with a long PBMA chain length. The results clearly indicate that covalent grafting is superior to physisorption with regard to thermal and mechanical properties of the final nanocomposite. This unique study is of great value for the future design of CNC-based nanocomposites with tailored properties.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
Keywords
cellulose nanocrystals (CNCs), covalent grafting physisorption, reversible-deactivation radical polymerization (RDRP), poly(epsilon-caprolactone) (PCL), nanocomposites
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-217193 (URN)10.1021/acsami.7b09009 (DOI)000413131500079 ()28895728 (PubMedID)2-s2.0-85031302620 (Scopus ID)
Funder
Swedish Foundation for Strategic Research , EM11-0022
Note

QC 20171102

Available from: 2017-11-02 Created: 2017-11-02 Last updated: 2019-01-23Bibliographically approved
4. Improved Cellulose Nanofibril Dispersion in Melt-Processed Polycaprolactone Nanocomposites by a Latex-Mediated Interphase and Wet Feeding as LDPE Alternative
Open this publication in new window or tab >>Improved Cellulose Nanofibril Dispersion in Melt-Processed Polycaprolactone Nanocomposites by a Latex-Mediated Interphase and Wet Feeding as LDPE Alternative
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2018 (English)In: ACS Applied Nano Materials, ISSN 2574-0970, Vol. 1, no 6, p. 2669-2677Article in journal (Refereed) Published
Abstract [en]

This work reports the development of a sustainable and green one-step wet-feeding method to prepare tougher and stronger nanocomposites from biodegradable cellulose nanofibrils (CNF)/polycaprolactone (PCL) constituents, compatibilized with reversible addition fragmentation chain transfer-mediated surfactant-free poly(methyl methacrylate) (PMMA) latex nanoparticles. When a PMMA latex is used, a favorable electrostatic interaction between CNF and the latex is obtained, which facilitates mixing of the constituents and hinders CNF agglomeration. The improved dispersion is manifested in significant improvement of mechanical properties compared with the reference material. The tensile tests show much higher modulus (620 MPa) and strength (23 MPa) at 10 wt % CNF content (compared to the neat PCL reference modulus of 240 and 16 MPa strength), while maintaining high level of work to fracture the matrix (7 times higher than the reference nanocomposite without the latex compatibilizer). Rheological analysis showed a strongly increased viscosity as the PMMA latex was added, that is, from a well-dispersed and strongly interacting CNF network in the PCL.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-241449 (URN)10.1021/acsanm.8b00376 (DOI)000461400700029 ()
Note

QC 20190123

Available from: 2019-01-22 Created: 2019-01-22 Last updated: 2019-04-23Bibliographically approved
5. Exploiting poly(ɛ-caprolactone) and cellulose nanofibrils modified with latex nanoparticles for the development of biodegradable nanocomposites
Open this publication in new window or tab >>Exploiting poly(ɛ-caprolactone) and cellulose nanofibrils modified with latex nanoparticles for the development of biodegradable nanocomposites
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2018 (English)In: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569Article in journal (Refereed) Published
Abstract [en]

This study reports the development of nanocomposites based on poly(?-caprolactone) (PCL) and cellulose nanofibrils (CNF) modified with cationic latex nanoparticles. The physical adsorption of these water-based latexes on the surface of CNF was studied as an environment-friendly strategy to enhance the compatibility of CNF with a hydrophobic polymeric matrix. The latexes are composed of amphiphilic block copolymers based on cationic poly(N,N-dimethylaminoethyl methacrylate-co-methacrylic acid) as the hydrophilic block, and either poly(methyl methacrylate) or poly(n-butyl methacrylate) as the hydrophobic block. The simple and practical melt-mixing of PCL- and latex-modified CNF yielded white homogeneous nanocomposites with complete embedment of the nanofibrils in the thermoplastic matrix. All nanocomposites are semicrystalline materials with good mechanical properties (Young's modulus?=?43.6?52.3 MPa) and thermal stability up to 335?340°C. Degradation tests clearly showed that the nanocomposites slowly degrade in the presence of lipase-type enzyme. These PCL/CNF-latex nanocomposite materials show great promise as future environmentally friendly packaging materials. POLYM. COMPOS., 2018. ? 2018 Society of Plastics Engineers

Place, publisher, year, edition, pages
John Wiley & Sons, Ltd, 2018
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-241451 (URN)10.1002/pc.24865 (DOI)000463102200009 ()2-s2.0-85045412566 (Scopus ID)
Note

QC 20190123

Available from: 2019-01-22 Created: 2019-01-22 Last updated: 2019-04-29Bibliographically approved
6. In situ encapsulation of Nile red or Doxorubicinduring RAFT‐mediated emulsion polymerizationvia PISA
Open this publication in new window or tab >>In situ encapsulation of Nile red or Doxorubicinduring RAFT‐mediated emulsion polymerizationvia PISA
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(English)Manuscript (preprint) (Other academic)
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-241454 (URN)
Note

QC 20190123

Available from: 2019-01-22 Created: 2019-01-22 Last updated: 2019-01-23Bibliographically approved
7. Film formation of soft and rigid PISA‐latexes –analysis of thin films using GISAXS
Open this publication in new window or tab >>Film formation of soft and rigid PISA‐latexes –analysis of thin films using GISAXS
(English)Manuscript (preprint) (Other academic)
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-241452 (URN)
Note

QC 20190123

Available from: 2019-01-22 Created: 2019-01-22 Last updated: 2019-01-23Bibliographically approved
8. Nanoparticle Rearrangement Under Stress inCellulose Nanofibrils Networks using in situ SAXSMeasurements During Tensile Testing
Open this publication in new window or tab >>Nanoparticle Rearrangement Under Stress inCellulose Nanofibrils Networks using in situ SAXSMeasurements During Tensile Testing
(English)Manuscript (preprint) (Other academic)
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-241456 (URN)
Note

QC 20190123

Available from: 2019-01-22 Created: 2019-01-22 Last updated: 2019-01-23Bibliographically approved
9. Cationic latexes of bio‐based hydrophobicmonomer Sobrerol methacrylate (SobMA)
Open this publication in new window or tab >>Cationic latexes of bio‐based hydrophobicmonomer Sobrerol methacrylate (SobMA)
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-241457 (URN)
Note

QC 20190123

Available from: 2019-01-22 Created: 2019-01-22 Last updated: 2019-01-23Bibliographically approved

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The full text will be freely available from 2020-02-01 15:00
Available from 2020-02-01 15:00

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Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
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  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
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  • Other locale
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Output format
  • html
  • text
  • asciidoc
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