P. [ULY et al.: POLY(VINYL ALCOHOL): FORMULATION OF A POLYMER INK FOR THE PATTERNING OF SUBSTRATES ...
41–48
POLY(VINYL ALCOHOL): FORMULATION OF A POLYMER INK
FOR THE PATTERNING OF SUBSTRATES WITH A
DROP-ON-DEMAND INKJET PRINTER
POLI(VINIL ALKOHOL): SESTAVLJANJE POLIMERNEGA ^RNILA
ZA TISKANJE PODLAG Z BRIZGALNIM TISKALNIKOM
Pavol [uly, Petr Kr~máø, Jan Ma{lík, Pavel Urbánek, Ivo Kuøitka
Tomas Bata University, Centre of Polymer Systems, Tr. Tomase Bati 5678, 760 01 Zlin, Czech Republic
suly@ft.utb.cz
Prejem rokopisa – received: 2015-07-01; sprejem za objavo – accepted for publication: 2016-01-19
doi:10.17222/mit.2015.180
Nowadays, inkjet-printing technology is considered one of the most promising deposition techniques. It allows the highly
precise deposition of functional materials to the required place on a substrate and a cost-saving printing process, especially
when the drop-on-demand manner is used. Moreover, it represents the perfect technique for the controlled deposition of polymer
material, especially for polymer solutions, because of their low viscosity and better process ability. Poly(vinyl alcohol) was
chosen because of its versatile application potential; moreover, its compatibility with the human body only increases its usability
in bio-applications. The main purpose of this research was to find the appropriate solvent system for poly(vinyl alcohol) and its
printability. Solutions with the best properties were printed in pre-defined patterns and personally defined motifs and the
printing conditions were optimized in order to obtain patterns with the best possible shape and resolution, which were analysed
by optical microscopy.
Keywords: inkjet ink, poly(vinyl alcohol), printed patterns, viscosity, surface tension
Dandanes tehnologija tiskanja z brizganjem predstavlja eno najobetavnej{ih tehnik za nana{anje. Omogo~a zelo natan~en nanos
funkcionalnih materialov na dolo~eno mesto na podlago, je cenovno ugoden proces, {e posebno pri zahtevnem posebnem na~inu
tiskanja. Poleg tega predstavlja odli~no tehniko za kontroliran nanos polimernega materiala, {e posebno raztopine polimera,
zaradi nizke viskoznosti in bolj{e sposobnosti procesa. Zaradi vsestranske mo`nosti uporabe je bil izbran poli(vinil alkohol),
poleg tega pa njegova kompatibilnost s ~love{kim telesom pove~uje mo`nosti biouporabe. Glavni namen te raziskave je bil
poiskati primeren sistem raztapljanja poli(vinil alkohola) s sposobnostjo za tiskanje. Raztopine z najbolj{imi lastnostmi so bile
uporabljene pri tiskanju dolo~enih vzorcev in osebno opredeljenih motivov. Pogoji tiskanja so bili optimirani za doseganje
vzorcev z najve~jo mo`no obliko in lo~ljivostjo, kar je bilo analizirano s svetlobno mikroskopijo.
Klju~ne besede: ~rnilo za brizganje, poli(vinil alkohol), tiskani vzorci, viskoznost, povr{inska napetost
1 INTRODUCTION
Inkjet printing (IJP) can be considered as an ideal
manufacturing tool for the preparation of thin films or
various shape patterns at required places. This technique
is also suitable for patterning fragile as well as flexible
substrates. In principle, the ink is converted into droplets
that are ejected through nozzles and delivered onto the
required place according to a predefined pattern con-
trolled by a computer unit.
The droplets are supplied either continuously or on
demand, which describes the two basic forms of IJP. The
first type, continuous inkjet printing, is mainly used for
coding; the stream of liquid is broken up into stream of
droplets that are charged electrically. The required drop-
lets are deflected during the flight through the deflection
plate and delivered to the substrate; the non-deflected
droplets are collected in a gutter, passed through the
filter and reused (depending on the arrangement of the
apparatus). On the other hand, the droplets are formed
only when needed by a heater or piezo-element in drop-
on-demand (DOD) manner of inkjet printing, resulting in
smaller drop size generation and higher placement
accuracy in comparison with continuous IJP.1 Inkjet
printing technology is used as a manufacturing tool in
different industrial fields. There are numerous applica-
tion examples of IJP, for instance, the technique is used
to prepare organic light-emitting diodes (OLED) and
polymer light-emitting diodes (PLED); printed electro-
nics including sensors, solar cell, circuits; rapid proto-
typing; life science application including enzyme-based
sensors, tissue engineering; and the other application
such as flexible displays, magnetic and memory applica-
tions, and thin-film transistors.2–4 Moreover, the potential
of IJP was successfully demonstrated in biological and
pharmaceutical applications, as in 1,5.
The IJP can be considered for a relative simple pro-
cess, if all requirements are fulfilled. The requirements
can be divided into four groups, namely: ink materials,
substrate properties, droplet formation and the printing
algorithm. Each element plays an important role in the
whole printing system. The viscosity, surface tension and
particles size represent the ink material group; for
substrate, the crucial parameters are wettability, surface
Materiali in tehnologije / Materials and technology 51 (2017) 1, 41–48 41
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967-2017) – 50 LET/50 YEARS
UDK 67.017:661.725.8:621.647.3 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 51(1)41(2017)
energy and surface structure. Other properties are related
to printing conditions, such as as drop generation, plat-
form, and algorithm. These parameters include the type
of used actuator, droplet size, printing procedure and
others.6
In a polymer system the viscosity of the solutions or
dilute solutions is defined by polymer concentration. In
general, the viscosity of the solution increases with in-
creasing content of the polymer at the same temperature,
and opposite, the viscosity decreases with increasing
temperature independently on the polymer concentration.
A similar effect of temperature can be observed for the
surface tension, but in this case, the overall change of
surface tension is not as significant as in the case of the
viscosity. Surface tension influences both the drop for-
mation during the flight from nozzle to substrate and the
wettability of printed substrate.
The shapes and quality of the printed patterns or
motives depend on the required resolution and other
parameters. N. Perinka et al.7 investigated the quality and
morphology of printed motives using different print-head
volumes, substrate temperatures, and firing voltages.
They observed that each parameter significantly affects
the final quality and uniformity of printed motives. The
quantity of deposited material can be affected by firing
voltage as well as the print-head volumes. The substrate
temperature showed an important influence on the final
morphology of the prepared layer.
IJP is ideal manufacturing tool for material depo-
sition. There are a lot of articles focused on printing of
dispersion and polymers used mainly in printed electro-
nics; however, only few of them are focused on printabi-
lity of water-soluble polymers (for example poly(vinyl
alcohol), polyvinylpyrrolidone, polyacrylic acid, poly-
acrylamides and other).
In this work, the poly(vinyl alcohol) solutions were
prepared in various polar solvents and their mixtures.
The viscosity and surface tension of each solution were
determined and adjusted so that the optimal values were
achieved. The solutions with the best properties were
then printed with a piezoelectric drop-on-demand mate-
rial printer on a flexible substrate made from poly-
ethylene terephthalate. Finally, the printed patterns were
analysed microscopically. The main purpose of this
research is finding the ideal solvent system for PVA and
its printability.
2 EXPERIMENTAL PART
2.1 Materials
Two commercial poly(vinyl alcohols) (PVA) that
represent water-soluble polymers, and Dimethyl sulph-
oxide (DMSO) for UV spectroscopy grade, 99.8 %
(GC), were purchased from Sigma-Aldrich. The main
PVA characteristics are listed in Table 1. Distilled water
was used as a major solvent. A food colorant was used
for better visibility of printed layer onto polymer flexible
substrate made from coated polyethylene terephthalate.
Table 1: The basic characteristics of poly(vinyl alcohols)
Tabela 1: Osnovne zna~ilnosti poli(vinil alkoholov)
Sample PD* DH* Mw*
Mowiol® 6-98 1000 98.0–98.8 mol.% ~47,000
Mowiol® 4-98 600 98.0–98.8 mol.% ~27,000
* where PD is polymerization degree, DH is degree of hydrolysis, and
Mw is weight average molecular weight
The pure PVA solutions at different concentrations
were prepared by dissolving of granulated PVA in
distilled water at 85±2 °C and continual stirring. Then,
the different surfactants were added to solutions to de-
crease the surface tension. Later, the PVA was dissolved
in a mixture of distilled water/DMSO in the volume ratio
2:1. DMSO has two roles in the used system, firstly as a
co-solvent that has higher boiling point than water;
secondly as a surfactant to decrease the surface tension
of PVA solutions. All solutions were passed through a
syringe filter (LUT Syringe Filters PTFE (Labicom
s.r.o.) with pore size 0.24 μm) to eliminate the insoluble
particles and other impurities.
2.2 Methods
The crucial parameters of each inkjet ink are
viscosity, surface tension and conductivity at the jetting
conditions (temperature, shear rate and others). There-
fore, the viscosity and surface tension (SFT) measure-
ments were determined with the highest precision. The
viscosity measurements of the prepared solutions were
carried out using a capillary Ubbelohde viscometer, type
0a and Ia depending upon the solutions’ compositions
and the expected viscosity at laboratory temperature. The
density was determined by pycnometers. The final dyna-
mic viscosity was calculated from the determined kinetic
viscosity. The surface tension was carried out using a
force tensiometer K100 from KRÜSS (GmbH Germany)
using the plate method (also called the Wilhelmy plate
method). In this assessment, the plate is oriented perpen-
dicular to the interface, and the force exerted on it is
measured.
Solution with suitable properties were filled into
cartridges (type: piezo-driven jetting device with integra-
ted reservoir and heater) and printed by Dimatix Mate-
rials Printer DMP-2800 series (Fujifilm Dimatix) on the
coated PET foil. The printed patterns were analysed with
an optical microscope LEICA DVM2500 Digital Camera
(Leica Microsystems).
3 RESULTS AND DISCUSSION
3.1 Polymer-solvent system
Poly(vinyl alcohol) is a synthetic polymer that
contains polar -OH side groups attached to the main car-
bon backbone. These polar groups prefer an interaction
with the other group of the same affinity. In the other
words, polar polymer is more soluble in polar solvents
P. [ULY et al.: POLY(VINYL ALCOHOL): FORMULATION OF A POLYMER INK FOR THE PATTERNING OF SUBSTRATES ...
42 Materiali in tehnologije / Materials and technology 51 (2017) 1, 41–48
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967-2017) – 50 LET/50 YEARS
and conversely. Therefore, PVA is often dissolved in
polar solvents such as water, dimethyl sulphoxide,
ethylene glycol, and primary alcohols and others. It can
also be expected that water will be the dominant solvent
in all cases.
The properties of PVA, such as solubility, solvent
resistance, flexibility, crystallinity, and viscosity, are
affected mainly by its degree of hydrolysis (DH) and
polymerization degree (DP). A higher dissolving tempe-
rature is necessary for more hydrolysed PVA. Similar
behaviour occurred in the case of the comparison of two
PVA with same degree of hydrolysis, but different DP.
Moreover, these parameters also affect the viscosity of
the solutions. The higher viscosity is observed for PVA
with a higher DP or molecular weight and concentration
due to presence of long chains that enhance the forma-
tion intra- and inter-hydrogen bonds.8,9
The first problem is dissolving the temperature
associated with almost fully hydrolysed PVA used in this
work because; the dissolving process is performed
around 85 °C, at which the water evaporation process has
begun. Therefore, the dissolving was carried out using a
beaker covered by watch glass and a Petri dish; this
arrangement was also helpful to maintain a stable dis-
solving temperature. This problem could be also partially
solved by using any co-solvent with a higher boiling
point, whereby a higher boiling point of the solvent mix-
ture will be achieved. The high dissolving temperature
also avoids using the commonly primary alcohols as a
separate solvent because their boiling point does not
exceed 100 °C; for illustration, the following boiling
points are noted, methanol ~65 °C, ethanol ~78 °C and
propan-1-ol ~97 °C.10 But, they could be used as surfac-
tants due to their miscibility with water and low surface
tension.
Finally, the PVA 6-98 was dissolved in pure water
and water with the addition of ethanol. Ethanol was
added to the solution after cooling to ambient tempera-
ture in various mass fractions. The PVA 4 – 98 was dis-
solved in pure water and in a mixture of water/dimethyl
sulphoxide (volume ratio 2:1). It represents a good ratio
between the DMSO consumption and the needed value
of SFT for the solution. The selected ratio was chosen
after SFT measurements of mixtures water/DMSO in
different ratios (1:1, 2:1, 3:1 and 4:1) without any poly-
mer content.
3.2 Viscosity and surface tension
The basic characteristics of the solutions are listed
and discussed in this section. However, the reasons for
the used methods must be clarified. There are two main
groups for the classification of fluids according their
viscosity behaviour with respect to shear rate; Newtonian
and non-Newtonian that involves pseudo-plastic (shear-
thinning) and dilatant (shear-thickening) fluids. The
viscosity is independent over whole range of shear rate
for the Newtonian. In contrast, the viscosity is changed
within the shear rate in the case of non-Newtonian fluids.
The change of viscosity according to the shear rate is
typical for polymer solutions and the polymer concentra-
tion has an important role.11
If the print-head nozzle is considered as a long
capillary with a small diameter, then an apparent shear
rate could be calculated using the following Equation
(1):


 A
Q
R
=
⋅
⋅
4
3π
(1)
Where Q is the volumetric flow rate ( Q = S·v), R is the
capillary radius, S is the nozzle area, and v is the velocity
of the droplets (detected by drop-watcher camera). In the
results, the apparent shear rate must by corrected to the
true shear rate (using Rabinowitz correction), but the
value of the shear rate is above 1 × 105 s–1 in IJP.12
There are many studies in which the prepared inkjet
inks are characterized by simple methods, for example,
by a rolling balls AMVn viscometer13, a Brookfield vis-
cometer14, or by changing the geometry of conventional
rheometers. H. Dakhil and A. Wierschem15 reported the
possibility to measure low viscosities at high shear rate
by modification of a gap width in a commercial rota-
tional rheometer. L. Pan and P. E. Arratia16 presented a
PDMS-based microfluidic rheometer that can be used for
the measurement of fluids with a Reynolds number (Re)
below 1, and in range of shear rates up to 104 s–1.
The Re number is defined as the relative importance
of the inertia forces to viscous forces:
Re=
⋅ ⋅ 	


L
(2)
Where  and 
 are the solution density and viscosity,
 is the mean fluid velocity and L is a characteristic
length scale.16 In our case, we consider L as the nozzle
diameter and 	 as the droplet velocity during jetting.
Based on the observed data that are listed later, the
calculated values of the prepared solution according to
Equation (2) will be in the range 18.5–102.2, 22.0–39.7,
35.4–98.5, and 14.4–40.3 for aqueous PVA 6-98, PVA
6-98+ethanol, aqueous PVA 4-98, and PVA 4-98 in a
water/DMSO mixture, respectively. These values of the
Reynolds number correspond to a laminar flow for all
the prepared solutions inside of the nozzle.
The most important dynamic parameters of inkjet
inks are viscosity and surface tension. The measurements
of viscosity and SFT have been performed by static
methods due to both being impossible to measure at a
high shear rate and the basic characterisation of the
prepared solution for scientific purposes. However, based
on the above-mentioned references, the obtained results
hold up even for such high shear rate systems as IJP and
the data can be successfully used in ink-formulation
development. Tables 2 to 5 show the density, dynamic
viscosity and surface tension of the prepared PVA solu-
tions in different solvent systems at the laboratory tem-
P. [ULY et al.: POLY(VINYL ALCOHOL): FORMULATION OF A POLYMER INK FOR THE PATTERNING OF SUBSTRATES ...
Materiali in tehnologije / Materials and technology 51 (2017) 1, 41–48 43
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967-2017) – 50 LET/50 YEARS
perature. The dynamic viscosity, 
, values were cal-
culated by using following Equation (3):

  	= ⋅ (3)
where 	 is kinematic viscosity and  is the density of
solutions.
As can be seen, at the higher polymer concentration
the higher viscosity was observed for both cases of PVA
aqueous solutions, as for PVA 6-98 as for PVA 4-98.
However, the PVA 6-98 aqueous solutions show higher
viscosity values in comparison with the second one. This
difference is caused by the higher polymerization degree
(higher molecular weight), in which the presence of long
chains enhances the formation of intra- and inter-hydro-
gen bonding, as were discussed previously and notified
in 8,9.
Similar behaviour was also observed for the surface
tension. The SFT could be considered as a constant in
both cases, because the SFT oscillates around the mean
values 53 mN·m–1 for PVA 6-98 and 60 mN·m–1 for PVA
4-98, respectively. Although small differences are seen,
no upward or downward trend was recorded.
There are recommended values of viscosity and SFT
for inkjet inks enabling the preparation of functional
layers (or patterns) by the used material printer. The
values for viscosity are in range of 10–12 mPa·s, and
28–42 mN·m–1 for the surface tension, of course, at a
certain jetting temperature.17 The obtained values of the
SFT were higher than the recommended limits, thus, the
SFT was decreased by using miscible additives. The
available surfactant Triton X-100 and BYK-348 were
added at the beginning, but decreasing of SFT was not
observed. Moreover, Triton X-100 precipitated in the
PVA solution. Therefore, the SFT was decreased by
using the co-solvent. The different mass fraction of etha-
nol was added to PVA 6-98 solutions; the new concen-
tration of solutions was calculated by using following
Equation (4):
w M w M w M M1 1 2 2 3 1 2⋅ + ⋅ = ⋅ +( ) (4)
where wx is the weight fraction of polymer in solution
and Mx is the weight of solution.
As can be seen, the addition of ethanol resulted in a
small increase of the solution viscosity and lowers the
SFT (Table 3). The effect of ethanol content on density,
viscosity, and surface tension of binary water+ethanol
mixtures at different temperature was investigated in 18.
They determined a limit for the mole fraction of ethanol
at around 0.3; up to this limit the viscosity and density of
mixture water + ethanol increase significantly, they
reached maximum values at the mentioned value, and
then decrease up to characteristic values for pure ethanol.
For SFT, the simple downward trend was observed with-
out any anomaly or unexpected deflections.
In short, the addition of 20 % of mass fractions of
ethanol taken on the mass of solution, (corresponding to
~0.08 mole fraction of ethanol), resulted in a decrease of
SFT from 55 mN·m–1 to 41 mN·m–1 and an increase of
viscosity from 4 mPa·s to 6 mPa·s. A similar effect was
observed for each other solution with a defined amount
of ethanol.
P. [ULY et al.: POLY(VINYL ALCOHOL): FORMULATION OF A POLYMER INK FOR THE PATTERNING OF SUBSTRATES ...
44 Materiali in tehnologije / Materials and technology 51 (2017) 1, 41–48
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967-2017) – 50 LET/50 YEARS
Table 2: Density, dynamic viscosity and surface tension of PVA 6-98
aqueous solutions
Tabela 2: Gostota, dinami~na viskoznost in povr{inska napetost vodne
raztopine PVA 6-98
Concentration of
PVA 6-98
solutions (w/%)
Density
(kg·m–3)
Dynamic
viscosity (10–3
Pa·s)
Surface
tension
(10–3 N·m–1)
0.5 998 1.26 55.2
1.5 1001 2.06 55.8
2 1018 2.31 53.5
2.5 1003 3.14 50.9
3.5 1021 4.28 55.7
5 1058 7.35 53.9
Table 3: Density, dynamic viscosity and surface tension of PVA 6-98
aqueous solutions with ethanol
Tabela 3: Gostota, dinami~na viskoznost in povr{inska napetost PVA
6-98 vodne raztopine z alkoholom
Origin PVA
6-98 conc.
(w/%)
Content
of
ethanol
(w/%)
New
conc.
(w/%)
Density
(kg·m–3)
Dynamic
viscosity
(10–3
Pa·s)
Surface
tension
(10–3
N·m–1)
2.5 7.9 2.32 1007 3.27 48.2
2.5 11.8 2.24 1003 3.46 46.0
2.5 15.8 2.16 998 3.95 43.8
3.5 11.8 3.13 1004 5.41 47.2
3.5 15.8 3.02 1000 5.57 44.6
3.5 19.7 2.92 995 5.83 41.1
Table 4: Density, dynamic viscosity and surface tension of PVA 4-98
aqueous solutions
Tabela 4: Gostota, dinami~na viskoznost in povr{inska napetost vodne
raztopine PVA 4-98
Concentration of
PVA 4-98
solutions (w/%)
Density
(kg·m–3)
Dynamic
viscosity
(10–3 Pa·s)
Surface
tension
(10–3 N·m–1)
1 1016 1.33 60.0
1.5 1017 1.67 58.8
2 1018 1.97 61.1
2.5 1020 2.43 59.4
3 1021 2.64 60.2
4 1023 3.73 60.7
Table 5: Density, dynamic viscosity and surface tension of PVA 4-98
solutions in water/DMSO mixture
Tabela 5: Gostota, dinami~na viskoznost in povr{inska napetost
raztopine PVA 4-98 v me{anici voda/DMSO
Concentration of
PVA 4-98
solutions (w/%)
Density
(kg·m–3)
Dynamic
viscosity
(10–3 Pa·s)
Surface
tension
(10–3 N·m–1)
1 1069 3.42 53.8
1.5 1069 3.98 52.8
2 1071 5.19 53.8
2.5 1070 5.66 56.7
3 1073 7.25 56.3
4 1072 9.61 56.4
DMSO was chosen as a co-solvent for PVA 4-98. The
DMSO, polar solvent with higher boiling point than
water, was a mixture with water at certain ratio before
the dissolving process. In comparison with pure PVA
4-98 aqueous solutions, the solutions show lower surface
tension, but higher density and viscosity at the same con-
centration of polymer (Table 4 and 5). The density was
slightly increased (about 1.05 times), but the viscosity
was increased by 3 times. The mean value of SFT de-
creased by 5 mN·m–1 from 60 mN·m–1 to 55 mN·m–1. The
mean value of SFT of the PVA 4-98 solutions is similar
to the mean SFT value of PVA 6-98 aqueous solution.
The viscosities of PVA 4-98 solutions prepared in
water/DMSO are nearer to the recommended ink
properties than other ones.
3.3 Printing process
The solutions showed the best properties from each
polymer-solvent system were printed on flexible PET
foil. There was also proposed a pulse waveform that con-
sists of several stages that are defined by the slew rate,
duration, and magnitude of pulse voltage. A uniform
droplet velocity was achieved by adjusting the voltage at
each nozzle. Figure 1 and Figure 2 show the droplets
formation and ejection from the nozzle. As can be seen,
the droplets velocity (about 6 m·s–1) was very similar in
both cases. The mixture with ethanol did not show a sig-
nificant long-tail formation in comparison with the next
one. This long-tails disappeared several microseconds
later during the airborne stage.
The printing of the PVA 6-98 aqueous solution at any
concentration was impossible, probably due to the high
DP and its effects. The same results were obtained in the
case of the PVA 6-98 solution containing ethanol after
printing several lines. Approximately a half of cartridge
volume was consumed before clogging the nozzles that
could be associated with the content of ethanol because
of its low boiling point. Also, the relatively high tem-
peratures of both cartridge and substrate (33 °C and
45 °C, respectively) support the evaporation process that
occurs before the printing process itself. The cleaning
cycles were performed more often than for PVA 4-98 in
mixture water/DMSO. A similar effect was also obtained
for the PVA 4-98 aqueous solution.
The four basic groups of requirements important for
ink formulation that have been mentioned in theory
(materials – ink properties, substrate properties, droplet
formation and the printing algorithm) are important;
however, this work is focused on the preparation of an
appropriate formula of polymer ink for specific substrate
(coated PET foil). Thus, the modification of the substrate
surface and the properties were not considered. Also, the
printing algorithm (waveform) and its subgroups were
used in the same way in all experiments once they had
been optimized for the preparation of all the patterns.
The last important group (droplet generation) was im-
portant, because the voltage waveform was prepared and
applied for all solutions. Moreover, the uniform droplet
velocity was reached by modification of the voltage for
the needed nozzles. This voltage was different for each
prepared polymer-solvent system.
3.4 Analysis of printed patterns
Well-defined patterns were printed after optimization
of the printing conditions. The patterns include pre-
defined and personally proposed patterns (single dots or
P. [ULY et al.: POLY(VINYL ALCOHOL): FORMULATION OF A POLYMER INK FOR THE PATTERNING OF SUBSTRATES ...
Materiali in tehnologije / Materials and technology 51 (2017) 1, 41–48 45
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967-2017) – 50 LET/50 YEARS
Figure 3: Magnified area of rectangle-shape pattern prepared from
PVA 6-98 solution with 15.8 % of mass fractions of ethanol
Slika 3: Pove~ano podro~je {tirioglate oblike, pripravljene z raztopino
s 15,8 % masnim dele`em PVA 6-98 v etanolu
Figure 1: Droplets generation and their velocity, PVA concentration
2.5 % of mass fractions in water with ethanol (15.8 % of mass
fractions), firing voltage 28–32 V, temperature of cartridge 33 °C
Slika 1: Nastajanje kapljic in njihova hitrost, koncentracija PVA 2,5 %
masnega dele`a v vodi z etanolom (15,8 % masnega dele`a), napetost
pri brizganju 28 ~ 32 V, temperatura kartu{e 33 oC
Figure 2: Droplets generation and their velocity, PVA concentration
2.5 % of mass fractions in water/DMSO mixture, firing voltage 33 V,
temperature of cartridge 33 °C
Slika 2: Nastajanje kapljic in njihova hitrost, koncentracija PVA 2,5 %
masnega dele`a v me{anici voda/DMSO, napetost pri brizganju 33 V,
temperatura kartu{e 33 oC
dots array, rectangle-shape pattern with variation in reso-
lution, and other motives). In this work, only fractions of
prepared patterns are shown. Firstly, the simple rectan-
gular-shape pattern was printed from the PVA 6-98
solution with the addition of ethanol. The pattern is
shown in Figure 3. As can be seen, the pattern is not
uniform; there are places where the particular printed
lines affected each other (the left top corner), and in con-
trast, there are places where the solution ink is either
missing or exists in an insufficient amount (the right
bottom corner).
Depending on the observed results, the solution of
PVA 4-98 was used to prepare a single-lines pattern.
Based on the obtained results, the polymers with lower
molecular weight are more suitable for the IJP process in
comparison with a polymer with a high DP. This pro-
posal can be supported by the following series of pic-
tures. Figure 4 shows the printed lines of PVA aqueous
solution with a lower DP. As can be seen, the edges of
printed lines are not smooth, moreover, the bulging effect
was observed in a random part of the lines. It suggested
that the energy of the prepared ink was sufficient for
drop formation, but the delay time was insufficient to
eliminate this instability effect (bulging). The widths of
the printed layers are about 200 μm. The food colorant
was added to the solution to improve the visibility of the
patterns (the amount of colorant was 0.5 % of the mass
fractions given to the amount of solution). It was found
that the addition of colorant up to 1 % of mass fractions
has no influence on the structure of the printed patterns;
P. [ULY et al.: POLY(VINYL ALCOHOL): FORMULATION OF A POLYMER INK FOR THE PATTERNING OF SUBSTRATES ...
46 Materiali in tehnologije / Materials and technology 51 (2017) 1, 41–48
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967-2017) – 50 LET/50 YEARS
Figure 5: The set of lines of 2.5 % of mass fractions of polymer
solution PVA 4-98 in water/DMSO mixture, magnified: a) 40 times,
and b) 100 times, respectively
Slika 5: Mno`ica linij z 2,5 % masnega dele`a raztopine polimera
PVA 4-98 v me{anici voda/DMSO, pove~ano: a) 40 × in b) 100 ×
Figure 4: The set of lines of 3 % of mass fractions of aqueous
polymer solution PVA 4-98, magnified: a) 40 times, and b) 100 times,
respectively
Slika 4: Mno`ica linij s 3 % masnega dele`a raztopine polimera PVA
4-98, pove~ano: a) 40 × in b) 100 ×
Figure 6: Single droplets prepared from 2.5 % of mass fractions of
polymer solution PVA 4-98 in water/DMSO mixture, magnified 200
times, 254 μm drop spacing
Slika 6: Posamezne kapljice pripravljene iz 2,5 % masnega dele`a
polimera PVA 4-98 v me{anici voda/DMSO, pove~ano 200 ×, razdalja
med kapljicama 254 μm
however, the larger amount of colorant together with the
pattern’s resolution can lead to the formation of crys-
talline structures. Tube-like shape structures were ran-
domly situated on the surfaces of the patterns with a
diameter in the range of 0.5 μm up to 5 μm. The for-
mation of the crystalline structure also depends on the
drying condition.
The same pattern was also prepared from solution of
PVA 4-98 in a water/DMSO mixture (Figure 5). The
patterns are smoother, with good visible edges. The
width of these lines is about 250 μm and larger, which
could be caused by the better wettability of the substrate
by ink with a lower surface tension. Additionally, the last
mentioned ink was used to prepare patterns based on
single drops at accurate positions. The drop lines or drop
arrays were prepared at various drop spacings. The
results are shown in Figure 6. The distance between two
neighbouring droplets is 254 μm. The droplet diameter is
in the range 60–65 μm. The droplets show an almost
perfect circular shape, but their height is uneven. This
effect could be controlled by adjusting the evaporation
profile. In general, the effect is more visible at higher
temperatures of the substrate.7,19
4 CONCLUSION
Several solutions of PVA 6-98 and PVA 4-98 were
prepared to find the optimal composition formula for the
preparation of a polymer inkjet ink. The viscosity and
surface tension were determined. The PVA 6-98 aqueous
solutions were not suitable for the printing process at any
polymer concentration. Next, the defined amount of
ethanol was added to the solutions to decrease their sur-
face tensions. This effect was observed, but ethanol
probably caused the clogging of the print head nozzles
because of its vapours at printing temperatures. The PVA
4-98 with a lower molecular weight was used in the next
series of experiments. The pure PVA 4-98 aqueous solu-
tion at a certain concentration shows suitable properties
for IJP processing. Several patterns were prepared, but
the formation of the droplet and their jetting velocity
were not uniform during the whole printing process,
which led to the preparation of less accurate patterns.
The best results were obtained for solutions of PVA 4-98
prepared in a water/DMSO (2:1 v/v) solvent mixture.
The prepared ink showed the best properties for the pre-
paration of single drop patterns as well as other patterns
such as grid, lines, rectangles, and other. The preparation
of water-resistant patterns from PVA will be the goal of
future work as well as the preparation of more sophi-
sticated patterns. From a practical point of view, let us
note that the results could extend the potential of PVA
based formulations in the biological and medical
sciences.
Acknowledgements
This work was supported by the Ministry of Educa-
tion, Youth and Sports of the Czech Republic – Program
NPU I (LO1504). We also acknowledge the support of
the Internal Grant Agency of Tomas Bata University in
Zlín (number: IGA/CPS/2015/006).
5 REFERENCES
1 J. Li, F. Rossignol, J. Macdonald, Inkjet printing for biosensor
fabrication: combining chemistry and technology for advanced
manufacturing, Lab Chip, 15 (2015) 12, 2538–2558, doi:10.1039/
C5LC00235D
2 A. Hudd, Inkjet Printing Technologies, The Chemistry of Inkjet Inks,
S. Magdassi (Ed.), Singapore, World Scientific Publishing, 2010,
3–18
3 B. Derby, Inkjet printing of functional and structural materials: fluid
property requirements, feature stability, and resolution, Annual
Review of Materials Research, 40 (2010) 1, 395–414, doi:10.1146/
annurev-matsci-070909-104502
4 M. Singh, H. M. Haverinen, P. Dhagat, G. E. Jabbour, Inkjet
printing-process and its applications, Advanced Materials, 22 (2010)
6, 673–685, doi:10.1002/adma.200901141
5 Q. Zheng, J. Lu, H. Chen, L. Huang, J. Cai, and Z. Xu, Application
of inkjet printing technique for biological material delivery and
antimicrobial assays, Analytical Biochemistry, 410 (2011) 2,
171–176. doi:10.1016/j.ab.2010.10.024
6 C.-T. Chen, Inkjet Printing of Microcomponents: Theory, Design,
Characteristics and Applications, Features of Liquid Crystal Display
Materials and Processes, N. V. Kamanina, (Ed.), Rijeka, Croatia,
InTech, 2011, 43–60
7 N. Perinka, C. H. Kim, M. Kaplanova, Y. Bonnassieux, Preparation
and Characterization of Thin Conductive Polymer Films on the base
of PEDOT:PSS by Ink-Jet Printing, Physics Procedia, 44 (2013),
120–129, doi:10.1016/j.phpro.2013.04.016
8 J. Tao: Effects of Molecular Weight and Solution Concentration on
Electrospinning of PVA. M.S. thesis, Mechanical Engineering
Department, Worcester Polytechnic Institute, Worcester, MA, 2003
http://www.wpi.edu/Pubs/ETD/Available/etd-0613103-130015/unres
tricted/jtao.pdf, 20.6.2015
9 H. J. Endres, A. Siebert-Raths, Engineering Biopolymers: Markets,
Manufacturing, Properties and Applications, Carl Hanser Verlag,
Munich, 2011, 149–224
10 J. Vohlídal, A. Julák, K. [tulík, Chemické a analytické tabulky,
Praha: Grada Publishing, 1999, 177, 276, 369
11 T. Sochi, Flow of non-newtonian fluids in porous media, Journal of
Polymer Science Part B: Polymer Physics, 48 (2010) 23, 2437–2767,
doi:10.1002/polb.22144
12 X. Wang, W. W. Carr, D. G. Bucknall, J. F. Morris, High-shear-rate
capillary viscometer for inkjet inks, Review of Scientific Instru-
ments, 81 (2010) 6, 065106–, doi:10.1063/1.3449478
13 C. A. Lamont, T. M. Eggenhuisen, M. J. J. Coenen, T. W.L. Slaats,
R. Andriessen, P. Groen, Tuning the viscosity of halogen free bulk
heterojunction inks for inkjet printed organic solar cells, Organic
Electronics, 17 (2015), 107–114, doi:10.1016/j.orgel.2014.10.052
14 X. Nie, H. Wang, J. Zou, Inkjet printing of silver citrate conductive
ink on PET substrate, Applied Surface Science, 261 (2012),
554–560, doi:10.1016/j.apsusc.2012.08.054
15 H. Dakhil, A. Wierschem, Measuring low viscosities and high shear
rates with a rotational rheometer in a thin-gap parallel-disk configu-
ration, Applied Rheology, 24 (2014) 6, 63795–, doi:10.3933/
ApplRheol-24-63795
16 L. Pan, P. E. Arratia, A high-shear, low Reynolds number micro-
fluidic rheometer, Microfluidics and Nanofluidics, 14 (2013) 5,
885–894, doi:10.1007/s10404-012-1124-2
P. [ULY et al.: POLY(VINYL ALCOHOL): FORMULATION OF A POLYMER INK FOR THE PATTERNING OF SUBSTRATES ...
Materiali in tehnologije / Materials and technology 51 (2017) 1, 41–48 47
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967-2017) – 50 LET/50 YEARS
17 FUJIFILM Dimatix 2010, Fujifilm Dimatix Materials Printer
DMP-2800 series: User Manual, Document no. PM000040 Rev. 05,
http://www.lilliu.co.uk/resources/DMP/DMP2800GuideVersion2.0.
pdf, 20.6.2015
18 I. S. Khattab, F. Bandarkar, M. A. A. Fakhree, A. Jouyban, Density,
viscosity, and surface tension of water+ethanol mixtures from 293 to
323 K, Korean Journal of Chemical Engineering, 29 (2012) 6,
812–817, doi:10.1007/s11814-011-0239-6
19 Y. H. Yun, J. D. Kim, B. K. Lee, Y. W. Cho, H. Y. Lee, Polymer
inkjet printing: construction of three-dimensional structures at
micro-scale by repeated lamination, Macromolecular Research, 17
(2009) 3, 197–202, doi:10.1007/BF03218679
P. [ULY et al.: POLY(VINYL ALCOHOL): FORMULATION OF A POLYMER INK FOR THE PATTERNING OF SUBSTRATES ...
48 Materiali in tehnologije / Materials and technology 51 (2017) 1, 41–48
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967-2017) – 50 LET/50 YEARS