BR102014023458A2 - surface modified polymers, surface modification process and uses - Google Patents

Abstract

surface modified polymers, surface modification process and uses. The present technology deals with modified polymers, which are obtained from a decoration / surface modification / topography process of biodegradable and / or natural hydrophilic polymers such as starch, chitosan, alginate, polyhydroxybutyrate and their copolymers, poly (lactic acid). and their copolymers, cellulose and variations thereof, polycaprolactone among others with microcomponents as particles and fibers (oxides, hydroxides, minerals among others) or polymeric, inorganic nanotubes, nanofibers, clay nanoparticles, carbon, polysaccharides among others, which modify its ability to absorb water creating hydrophobic or superhydrophobic characteristics. The invention also proposes the use of these modified polymers for the manufacture of various products, especially packaging, medical / pharmaceutical products and textile industry products. The grafted components can still carry active molecules that can be useful in many applications (bactericidal character, electrical conductivity increase, among others).

Description

“MODIFIED SURFACE POLYMERS, SURFACE MODIFICATION PROCESS AND USES” [001] The present technology deals with modified polymers, which are obtained from a decoration / surface modification / topography process of biodegradable and / or natural hydrophilic polymers such as starch, chitosan, alginate, polyhydroxybutyrate and its copolymers, poly (iactic acid) and its copolymers, cellulose and variations thereof, polycaprolactone among others with microcomponents such as particles and fibers (oxides, hydroxides, minerals among others) or polymeric, inorganic nanocomponents, nanotubes, nanofibers, clay nanoparticles, carbon, polysaccharides, among others, which modify their water absorption capacity by creating hydrophobic or superhydrophobic characteristics. The invention also proposes the use of these modified polymers for the manufacture of various products, mainly packaging, medical / pharmaceutical products and textile industry products. The grafted components can still carry active molecules that can be useful in many applications (bactericidal character, electrical conductivity increase, among others).

[002] Polymers are widely used in various areas of industry and it is common to note that objects initially produced with other materials, particularly metal, glass or wood, have been replaced by polymeric materials.

[003] This expansion is mainly due to its most relevant characteristics, which are: low cost, low weight, high strength, variation of shapes and colors, and often perform better than previously used material. The most consumed types of polymers today are polyethylenes, polypropylenes, polystyrenes, polyesters and polyurethanes, which, due to their large production and use, are called commodity polymers. Other classes of polymers, such as polyacryotes, polycarbonates and fluoropolymers, have been increasingly used. [ABIPLAST, 2009. ABIPLAST <http://www.abiplastorg.br/index> accessed on 11/25/2009].

[004] The environmental impact associated with the increased consumption of polymeric materials stems from the inertness of these materials in biodegradation, which results in the accumulation of plastic waste in the environment. Thus, efforts to reduce such negative impacts involve developments aimed at reducing the amount of polymeric material employed in artifacts, the technical and economic feasibility of recycling polymeric material, and the use of biodegradable polymers [MALMONGE, S. M .; BELEM, L. P. Biodegradable Polymers: Structure X Properties X Biodegradation. <Http: // www. unimep br / phpg / showacademic / annals / 4show / pdfs / 103.pdf> accessed 25/11/2009]. Most of the biodegradable polymers used today have hydrophilic character, which causes high water absorption, which is responsible for deterioration of mechanical properties and dimensional stability.

The increasing search for polymers with hydrophobic surfaces with water contact angles above 150 ° and low hysteresis angles is related to their potential use in various self-cleaning applications and anti-adhesive coating properties. Many industrial products use water repellency on products such as umbrellas, sportswear and self-cleaning glass. Water repellent surfaces are obtained by controlling the rough surface and decreasing surface energy [OSAWA, S .; YABE, M .; MIYAMURA, M .; MIZUNO, K. Preparation of superhydrophobic surface on biodegradable polymer by transcribing microscopic pattern of water-repelient leaf. Polymer Communication, Japan, v.47, p3711-3714, marc. 2006]. There are also some repellents of natural origin such as the surface of the lotus leaf and the butterfly wing, whose morphology and chemical composition inspired the construction of artificial counterparts, generating an appropriate surface roughness (topography) on chemically hydrophobic surfaces [GONÇALVES, G. ; MARQUES, P. A. A. P .; TRINITY, T .; NETO, C. P .; GANDINI, A. Superhydrophobic cellulose nanocomposites. Journal of Colloid and Interface Science. Portugal, v. 324, p42-46, 2008].

Starch granules can be freeze-dried in the presence of a plasticizer (such as water and glycerol) and during heating when the crystal structure is destroyed. This plasticized starch is also called thermoplastic starch (TPS). One of the main disadvantages of TPS targeting packaging applications is its hydrophilic characteristic. One way to minimize this problem is to mix TPS with hydrophobic materials such as polyolefins (CnH2n) [TAGHIZADEH, A .; SARAZIN, P .; FAVIS, B. D .; High molecular weight plasticizers in thermoplastic starch / polyethylene blends. J Mater Sci, lssue 48, pages 1799-1811, 2013 - DOI 10.1007 / s10853-012-6943-8].

With this, mixtures such as TPS and low density polyethylene (LDPE) have been investigated. However, due to the high interfacial tension between starch and LDPE and the low polarity of LDPE, such mixtures require the use of compatibilizers [MORTAZAVI, S .; GHASEMI, S .; OROMIEHIE, A .; Effect of phase inversion on the physical and mechanical properties of low density polyethylene / thermoplastic starch. Polymer Testing, Volume 32, lssue 3, Pages 482—491, 2013 http://dx.doi.Org/10.1016/j.polymertesting.2013.01.004], Starch and polyethylene blends with surfaces with hydrophobic characteristics and even Superhydrophobic could restrict a longer contact between the surface of the polymer and water, which would allow its elimination (via evaporation or sliding) and consequent reduction of the possibility of its absorption by the material.

In the model proposed by Wenzel, the surface of a material of hydrophobic nature has a low energy value per unit area. A drop of water deposited on this surface is very close to the spherical shape. Highly water repellent surfaces have a contact angle of water greater than 120 ° and are obtained by controlling surface roughness and decreasing surface energy. Cassie-Baxter's model is based on the hypothesis that on a rough surface water is suspended over the surface roughness. Cassie and Baxter presented the idea that the apparent contact angle may be the result of contributions from different species that make up the surface.

Electrospinning is an innovative process that has been recognized as one of the most efficient techniques for the production of polymer nanofibers. It has been used in nanotechnology and materials science since 1980 and has increasingly attracted attention. This process allows the mass production of nanofibers of a variety of polymers. Theoretically, this is a fast and simple process driven by electrical forces on the surface of polymeric fluids, forming fibers with submicrometer diameters through the action of electrostatic forces.

[010] Scanning Electron Microscopy (SEM), Optical Microscopy (MO) and Atomic Force Microscopy (AFM) were used to visualize the distribution of micro / nano components on TPS / LDPE surfaces. The deposition processes, as well as the types of components deposited, made possible the control of the contact angle of the substrates, obtaining high contact angle (AC) values and low contact angle hysteresis values, including AC above 150 ° and contact angle hysteresis less than 10 °. Thus, it has been proved that the surface of natural biodegradable polymers and polyethylene / starch blends, which are intrinsically hydrophilic, can have their surface characteristics altered by creating topographic patterns by decorating with micro / nanocomponents to generate hydrophobic and super-smooth surfaces. - hydrophobic useful for minimizing water absorption by these materials.

[011] Patent application W02014063013 (A1) entitled "Apparatus and method for electrospinning to nanofiber coating on surfaces of poorly conductive three-dimensional objects" concerns the use of the electrospinning process and other methods for applying nanofibers to object surfaces. three-dimensional.

[012] There are no patent applications dealing with the surface decoration of biodegradable natural polymers and their blends with nano and microcomponents capable of promoting lower water absorption via hydrophobic and superhydrophobic surface formation and other features. Thus, the development of a modified polymer with special properties is extremely interesting for many industry sectors, as it can technically and economically enable the recycling of polymeric material and the use of biodegradable polymers.

[013] Microcomponents or nanocomponents used in surface decoration may, in addition to restricting water absorption, limit the development of bacteria and fungi which may contain bactericidal and fungicidal agents); increase electrical conductivity of surfaces that can reduce static electricity (by incorporating conductive polymers into nanocomponents); allow the release of components used as drugs. These special features may apply primarily to packaging, medical / pharmaceutical, and textile industries.

DESCRIPTION OF THE FIGURES

[014] Figure 1 shows the flowchart of the steps of the product preparation process.

Figure 2 shows a microcomponent deposition scheme.

[016] Figure 3 shows the equipment used in the electrospinning process and the nanofiber ejection system.

Figure 4 shows an Optical Microscopy (MO) image of a sample with 10% spongylite fibers.

[018] Figure 5 shows an Optical Microscopy (MO) image of a sample with 1% spongylite fibers.

[019] Figure 6 shows a sample Optical Microscopy (MO) image with 0.5% spongylite fibers.

[020] Figure 7 shows a graph of the contact angle relative to the deposition of spongylite fibers.

[021] Figure 8 shows the contact angle for substrates with hollow glass sphere deposition in starch obtained via hydrothermal and thermomechanical.

[022] Figure 9 shows the contact angle of the 25, 50 and 75% starch glass microspheres.

[023] Figure 10 shows a Scanning Electron Microscopy (SEM) image of the hydrothermal starch sample with 10% MPS deposition at 1000x magnification.

[024] Figure 11 shows a Scanning Electron Microscopy (SEM) image of the thermomechanical starch sample with 10% MPS deposition with 500x magnification.

[025] Figure 12 shows a Scanning Electron Microscopy (SEM) image of the thermomechanical starch sample with 10% MPS deposition at 1000x magnification.

[026] Figure 13 shows the contact angle of PCL nanofibers deposited on thermomechanical and hydrothermal starch substrates.

[027] Figure 14 shows the contact angle of PCL nanofibers deposited on 25%, 50% and 75% starch substrates in LDPE.

[028] Figure 15 shows a Scanning Electron Microscopy (SEM) image of the substrate containing 25% starch decorated with PCL nanofibers with a deposition time of 2 minutes.

Figure 16 shows a Scanning Electron Microscopy (SEM) image of the substrate containing 25% starch decorated with PCL nanofibers with a deposition time of 4 minutes.

[030] Figure 17 shows an Atomic Force Microscopy (AFM) image of the hydrothermally prepared starch sample with 2 minutes of PCL nanofiber deposition.

[031] Figure 18 shows the contact angle of PCL / DEXA nanofibers deposited on starch substrates obtained by thermomechanical and hydrothermal processing.

[032] Figure 19 shows the contact angle of PCL / DEXA nanofibers deposited on 25%, 50% and 75% starch substrates in LDPE.

[033] Figure 20 shows a Scanning Electron Microscopy (SEM) image of the PCL / DEXA decorated hydromechanical starch substrate with a deposition time of 2 minutes.

[034] Figure 21 shows a Scanning Electron Microscopy (SEM) image of the substrate containing 25% PCL / DEXA decorated starch with a deposition time of 5 minutes.

[035] Figure 22 shows ATR mode Infrared Absorption Spectroscopy (FTIR) spectra for (a) PCL nanofibers and (b) PCL / dexamethasone nanofibers, [036] Figure 23 shows contact angle of PCL / SULFA nanofibers from starch substrates obtained by thermomechanical and hydrothermal methods.

[037] Figure 24 shows the contact angle of PCL / SULFA nanofibers deposited on 25%, 50% and 75% starch substrates.

[038] Figure 25 shows the Scanning Electron Microscopy (SEM) image of the thermomechanically obtained starch sample with 2 minutes deposition of PCL / SULFA nanofipers.

[039] Figure 26 shows the Scanning Electron Microscopy (SEM) image of the thermomechanically obtained starch sample with 4 minutes of PCL / SULFA nanofiber deposition.

[040] Figure 27 shows Infrared Absorption Spectroscopy (FTIR) spectra for (a) PCL nanofiber samples and (b) for silver PCL / Sulfadiazine nanofibers.

DETAILED DESCRIPTION OF THE INVENTION

The modified polymers of the present technology comprise surface modified (decorated) polymeric films with the insertion of microcomponents and nanocomponents.

[042] The process of modifying microcomponent polymeric films comprises the following steps: A) Heating the polymeric film from 40 to 190 ° C; B) Dispersion of microcomponent as particles and fibers (oxides, hydroxides, minerals among others) in solvent such as water, alcohols, acetone, toluene, tetrahydrofuran, etc. at room temperature for 1 min; C) Scattering the dispersion in the heated film; D) Packaging of the product in desiccator.

[043] However, the process of modifying polymeric films can also be done with nanocomponents such as electrofinance polymeric nanofibers, as described below: A) Dissolution in solvents such as water, alcohols, acetone, toluene, tetrahydrofuran, acids, trifluoroethylene. polymer, such as polycaprolactone, poly (lactic acid) and its copolymers, starch, chitosan, polyhydroxybutyrate and their copolymers with or without the addition of components, under magnetic action; B) Transfer of the solution to a syringe and insertion into the electrospinning apparatus; C) Application of a potential difference; D) Sample collection; E) Deposition on the surface of the film.

[044] Polymeric films may be hydrophilic polymers (biodegradable and / or natural hydrophilic polymers such as starch, chitosan, alginate, polyhydroxybutyrate and its copolymers, poly (lactic acid) and its copolymers, cellulose and variations thereof, polycaprolactone among others) or blends thereof with each other or with other polymers such as polyethylene, polypropylene, polyamides, polyesters etc.

[045] Modified polymers can be used in packaging, medical / pharmaceutical, textile industry, etc. industries.

[046] The polymeric film used as a substrate to be decorated with microcomponents or nanocomponents may be based on natural biodegradable polymers such as cassava starch, for example. This film can be obtained by a thermomechanical (by shear and heat) or hydrothermal (by water and heat) process.

[047] In the present technology cassava starch based film was prepared by thermomechanical process as follows: The films were supplied by the Naviraí industry and, with the addition of Quattor low density polyethylene, were produced in 100/0, 25/75, 50/50 and 75/25 (by mass) starch / low density polyethylene (LDPE) ratios and 30% glycerol in relation to the total mass of the components and as a compatibilizer was used maleic anhydride graphitized polyethylene (Sigma-Aldrich) 2% of the total mass. The thermomechanical process of preparing the polymeric film comprises the following steps: a. Mix starch, polyethylene, glycerol and maleic anhydride graphitized polyethylene in a Thermo Haake torque rheometer (Polydrive, R / 600) at 150 ° C, with rotation speed between 30 and 45 rpm and mixing time of 10 minutes. B. Extrusion of material in single screw extruder (AX Plastics Technical Machines). ç. Pelletization of the material. d. Thermosetting press (Sagec) at 150 ° C for 10 minutes and pressure up to 5 tons.

In addition to the thermomechanical process of preparing the polymeric film, the hydrothermal process was also used. Hydrothermal films were prepared at 70/30 (by mass) starch / glycerol (Sigma-Aldrich) in 100 mL of water. The hydrothermal polymeric film preparation process comprises the following steps: a. Stirring and heating of materials at 70 ° C. B. Store the solution in an oven at 40 ° C for 48 hours.

In the surface decoration (modification) of the hydrothermally and thermomechanically produced starch films described above, microcomponents (spongilite, hollow glass spheres and 2-aminoethyl polystyrene microspheres) or nanocomponents (polycaprolactone nanofibers ( PCL), PCL and dexamethasone nanofibers (PCL / DEXA) and silver PCL and sulfadiazine nanofibers (PCL / SULFA)). The products obtained were: • Thermoplastic starch film (TPS) obtained by hydrothermal and thermomechanical decoration, decorated with spongilite. • Thermoplastic starch film (TPS) obtained via hydrothermal and thermomechanical, decorated with hollow glass spheres. • Thermoplastic starch film (TPS) obtained hydrothermally and thermomechanically, decorated with 2 aminoethyl polystyrene (MPS) microspheres. • Thermoplastic starch film (TPS) obtained via hydrothermal and thermomechanical, decorated with polycaprolactone nanofibers (PCL). • Thermoplastic starch film (TPS) obtained hydrothermally and thermomechanically, decorated with polycaprolactone (PCL) and dexamethasone (DEXA) nanofibres (PCL / DEXA). • Thermoplastic starch film (TPS) obtained hydrothermally and thermomechanically, decorated with polycaprolactone (PCL) and silver sulfadiazine (SULFA), (PCL / SULFA) nanofibers.

[050] The treated matter can be better understood by the following non-limiting examples: Example 1 - Decoration of the film with microcomponents [051] The films were cut into 1 cm x 1 cm plates and kept in a desiccator (Figure 2 ).

Microcomponent deposition occurred by heating the samples to a temperature of approximately 80 ° C (polymer softening temperature). Table 1 lists the microcomponents used.

Table 2: Proportions of spongilite fibers used in relation to the sample surface: [053] The following steps were performed: [054] Spongilite a. Dispersion of spongylite fibers in the proportions shown in table 2 in absolute ethyl alcohol (99% Modern Chemistry). B. Dispersion of the spongilite fibers on the heated substrate surface until the alcohol evaporates. ç. Conditioning the samples in a desiccator for 24 hours for fiber adhesion to the samples (Figure 2).

Hollow glass spheres The same procedure as for Spongylite fibers was used, in the proportions of 5 and 10% of spheres in relation to the surface occupation of the substrate.

Polystyrene 2-aminoethyl microspheres (MPS) a. Dispersion of samples in the proportions of 10 to 5% with the aid of cutting-edge ultrasound, model Branson Ultrasonics Corporation, for 10 minutes in absolute ethyl alcohol (99% Modern Chemistry). B. Dispersion drip onto the substrate surface until the alcohol evaporates.

Example 2 - Nanocomponent Film Decoration Poiicaprolactone (PCL) nanofibers with 80,000 to 90,000g / mol molar mass (Sigma Aldrich) were initially prepared by dissolving the PCL in a formic acid / acetic acid mixture (1 : 1), (solution containing 14.6 wt% PCL). Dissolution occurred under magnetic stirring for 4 hours at room temperature. Pure solutions and solutions with component additions such as silver sulfadiazine (Sigma Aldrich), dexamethasone were produced. The electrospinning process was then performed with the aid of the Instor apparatus (Figure 3) according to the following steps: a. The polymeric solution was transferred to a 5 ml glass syringe (Arti Glass, CE, Italy) with orthogonal (22G 1) metal needle (hypodermic irrigation needle, Konnen) and adapted to the electrospinning device (Figure 3). . The flow rate used was 3.0 ml / h. B. A voltage of + 25 / 0kV (ie 25kV on the needle and OkV on the collector) was applied. ç. Samples were placed on the 8 cm diameter automated rotating disc (90 rpm). d. The nanofibers were deposited on the starch and starch / PE samples with deposition time variation of 2, 3, 4 and 5 minutes. The temperature inside the electrospinning chamber was 25.3 ° C and 58% humidity. The arrangement of the syringe and collecting disc was made in an upright position with a distance of 8 cm between them.

[058] The same electrospinning parameters previously mentioned were also used for the production of nanofibers with addition of components as shown in Table 3. The deposition made directly on the surface inside the electrophony equipment also followed the same procedure with time intervals. 2, 3, 4 and 5 minutes as for pure PCL.

Table 3: Composition of the nanofibres produced by electrophony: Example 3 - Characterization through contact angle and hysteresis [059] The classic technique for characterizing hydrophobia is contact angle (AC). This technique allows the understanding of the thermodynamic properties of material surfaces. For the determination of the static contact angle, there are several ways for proper measurement. The most common are the tangent fit method and the sessile method. The method used in this work was the static droplet sessile method, which consists of an optical system with a light source and the camera that detects the droplet profile in contact with the substrate surface.

Spongilite: [060] The contact angles for the spongilite fiber samples on the surface of the starch sample produced by the hydrothermal process, with 10% 1% and 0.5% occupancy, visualized by optical microscopy, were 110 ° , 130 ° and 75 °, respectively. This result supports the theory proposed in the Cassie-Baxter model, which predicts high contact angle values for topographies with constituents separated by micrometer distances. The AC value for 0.5% occupancy is lower, since the distance between the fibers is no longer enough to support the drop of water. This result confirms the hypothesis that hydrophilic substrates decorated with also hydrophilic microcomponents (since pure silica also has low contact angles) may have high contact angles, provided that the generated topographic pattern is sufficient to support a drop of water.

[061] Starch-based substrates obtained by hydrothermal and thermomechanical processes and with 25, 50 and 75% starch fractions in LDPE showed significant wettability changes with spongilite deposition, Figure 7, producing surfaces with hydrophobic characteristics. As shown above, low concentrations of spogilite on surfaces favor the increase of AC due to the possibility of water drop support. Higher spongilite concentrations reduce the average distances between topographic entities and lead to a decrease in this angle.

[062] The hysteresis angles in all cases did not exceed 4 ° which characterizes the self-cleaning behavior as the droplets can slide over the surface quickly. In addition to self-cleaning, this behavior is also ideal for potentially minimizing water absorption by substrates, as the contact time of water droplets with substrates is reduced as they tend to move, be eliminated from substrates or evaporate [HOZUMIA , A.; CHENG, D.F.YYAGIHASHI, M. Hydrophobic / superhydrophobic oxidized metal surfaces showing negligible contact angle hysteresis. Journal of Colloid and Interface Science. Volume 353, Issue2, 2011, Pages 582-587 http://dx.doi.org/10.1016/jjcis.2010.09.075].

Hollow Glass Spheres: [063] It can be seen from Figure 8 that the contact angle of starch samples manufactured via hydrothermal gelatinization process showed an increase in hydrophobia to both 10% and 5% surface occupancy with glass spheres. Already, the starch samples from the thermomechanical processing showed an increase of contact angle for the samples with only 5% of surface occupation with spheres. Concentrations of 10% of deposited spheres probably generated distances between decorative entities smaller than those suitable for air pocket formation as predicted by Cassie-Baxter. These results prove the possibility of changing the wettability of materials (making them more hydrophobic) by decorating the surfaces, even with intrinsically hydrophilic microcomponents. The topographic pattern fabricated by the random distribution of hollow glass spheres on the starch surface would be responsible for sustaining the water droplet. Since the substrate is hydrophilic and would quickly absorb the water drop, it can be said that the Wenzel model does not contemplate the system because it proposes the contact of the drop with the surface. The system studied in this work is more in line with the Cassie-Baxter model, which predicts the full support of the drop without contact with the substrate, which favors an increase in the relative hydrophobic character of the sample surface.

[064] Substrates with 25%, 50% and 75% showed similar behavior to the hydrothermal surface, with an increase in AC, which allows the droplet to sustain with the formation of air pockets between the fibers, and its decrease with the increasing the amount of hollow glass microspheres.

This is because the larger the number of beads used the more uniform the layer on the substrate, becoming a second layer, as shown in Figure 9.

2 Aminoethyl Polystyrene (MPS) Microspheres: [065] The presence of a coarse texture (formed by the agglomerates of spheres) and a more refined texture due to the individualized spheres in each agglomerate on starch substrates (obtained hydrothermally, Figure 10). 1000x magnification, and thermomechanical magnification with 500 and 1000x magnification (Figures 11 and 12) allowed the measurement of AC of 152 ° and 150 °, respectively. This result characterizes superhydrophobic surfaces. Low hysteresis values suggest a very low rolling angle to water (the angle at which the drop will roll off the surface) and this property is very important in some applications such as self-cleaning surfaces and drag reduction. The high value of this hysteresis angle, in extreme cases, can result in the so-called gecko state, where a drop of water adheres to the surface and it can be inverted with the drop of water suspended. A drop of water placed on a sticky hydrophobic surface will have a very high contact angle, but will also stick to the surface [WANG, J .; LI, A. CHEN, H .; CHEN, D. Synthesis of Biomimetic Superhydrophobic Surface through Electrochemical Deposition on Porous Alumina, Journal of Bionic Engineering, Volume 8, Issue 2, 2011, Pages 122-128 http://dx.doi.org.ez27.periodicos.capes.gov .br / 10.1016 / S1672-6529 (11) 60022-X], In the case of hydrothermally and thermomechanically obtained starch substrates with 10% of their surfaces occupied by MPS microspheres, the hysteresis angles were 2.8 ° and 3 ° C. , 5 °, respectively, which characterize a self-cleaning superhydrophobic surface.

[066] Substrates with 25%, 50% and 75% starch in polyethylene with 10% surface occupancy by MPS microspheres had high AC values as well as low contact angle hysteresis values (Table 4). In these situations, the low hysteresis value can also attribute to the surface self-cleaning feature.

Table 4: AC and hysteresis of starch blends containing PE and 10% MPS microspheres: The samples containing 5% microcomponents showed a less hierarchical arrangement of the microspheres than in the 10% microsphere samples. In this case, the distance between the components was not sufficient to support the drops and the measured CA were below 60 °. NANOFIBRAS: [068] Pure and dense PCL films were obtained by casting molds of solutions similar to those used in electrophony. Dense PCL films containing the components reported in Table 5 were also prepared via casting. The CA of these films was evaluated and the values are described in Table 5.

Table 5: AC results of cast films based on PCL: PCL nanofibers: [069] Nanofibers obtained by electrophony were deposited directly on the substrate surface. In order to create different topographic patterns on substrate surfaces, nanofiber deposition times were varied. Thus, substrates containing fibers collected with two, three, four and five minutes of electrophony were obtained. Figures 13 and 14 show a behavior in which there is an increase in contact angle followed by a decrease of this AC as a function of the time deposition of PCL nanofibers on starch substrates (obtained by thermomechanical and hydrothermal).

[070] The longer the nanofiber deposition time, the greater the density of fibers present in the substrate and the shorter the distance between the nanofibers. Smaller distances between nanofibers are less able to withstand water droplets, resulting in a lower degree of hydrophobia. The same behavior is observed in substrates based on starch and LDPE blends (Figure 14). The differences in AC values observed may be associated with the diameter variations of the produced nanofibers. Larger nanofiber diameters, seen in Figures 15 and 16, tend to continuous films with reduced contact angle and distances between nanofibers, which impose restrictions on the stabilization of water droplets. There is also a tendency to reduce nanofiber diameter with deposition time, as the progressive deposition of polymeric fibers modifies the electrical characteristics of the substrate. This reduction in diameter can lead to an increase in the distance between nanofibers and, consequently, greater degrees of hydrophobia.

[071] The values for contact angle hysteresis show a low value, previously presented as the surface bearing of the drop for contaminant drag. In hydrothermally obtained starch substrates, and those with 25% LDPE starch, there is practically no change in hysteresis with deposition time.

PCL and dexamethasone nanofibers (PCL / DEXA): [072] The incorporation of dexamethasone (a steroidal anti-inflammatory) into PCL nanofibers, in addition to offering the possibility of creating biologically active surfaces, has provided a reduction in nanofiber diameter and , as a consequence, the increase of AC in the surfaces with deposited nanofibres, due to a greater distance between them. For thermomechanically obtained starch substrates, the addition of DEXA considerably increased the AC values as shown in Figure 18 at all deposition times (when compared to those for pure PCL nanofiber systems). . And in the same figure, the AC for the hydrothermal starch substrates are also shown, which also show an increase in the contact angle value for a two minute deposition time. The behavior shown in Figure 18 also involves a pronounced increase in contact angle when depositing the first layers of nanofibers due to the presence of a regular topography that is useful for sustaining water droplets. Continued nanofiber deposition leads to a reduction in AC values (probably due to fiber compaction and reduction of distances between them), followed by a new trend of increased contact angle as a result of reduced nanofiber diameter with the evolution of the electrophony process.

[073] Figure 19 shows the AC values for starch and LDPE blends substrates. Regarding the deposition of pure PCL nanofibers on the same substrate types, the surfaces of the samples with 25% and 50% starch presented higher values for all deposition times, characterizing hydrophobic surfaces. The sample with 75% presented a decrease of this value.

[074] The evolution of CA as a function of deposition time is close to previous cases, ie: 1. Increased contact angle with the initial deposition of nanofibers, due to the creation of a textured surface that presents the characteristics recommended by the model. Cassie-Baxter for holding water droplets by the presence of air pockets; 2. Reduction of AC for deposition times around 3 minutes as a result of increased nanofiber compaction on the substrate surface; 3. Further progressive increase of contact angle for longer deposition times. as a result of a refinement of the nanofiber diameter with the evolution and stabilization of the electrofinning process. Such a decrease in nanofiber diameter can increase the distance between them and even create hierarchical dimensional patterns (ie, as topographically finer and coarser regions); 4. For some systems: a subsequent reduction in AC is observed for 5 minute deposition times due to full surface occupancy by nanofibers.

[075] The issues reported above are illustrated in Figures 20 and 21, including the perception of the presence of surfaces with high nanofiber concentration after 5 minutes of deposition (Figure 21).

[076] For all substrates and deposition times of dexamethasone PCL nanofibres studied, contact angle hysteresis showed low values (always below 5o) characterizing surfaces with low adhesion and high self-cleaning behavior.

PCL Nanofibers and Silver Sulfadiazine (PCL / SULFA): [077] The incorporation of silver sulfadiazine in PCL nanofibers deposited on the surface of biodegradable polymers can also generate biologically active surfaces with bactericidal characteristics. In addition, the presence of silver sulfadiazine was also useful in decreasing fiber diameter and increasing system AC values. According to the results presented, the addition of silver sulfadiazine favored, in all cases, the expansion of hydrophobic surface characteristics. In the case of thermomechanical starch substrate surfaces, and with two minutes of deposition of PCL nanofibers with silver sulfadiazine, a superhydrophobic surface was observed, Figure 23, ie, with contact angles greater than 150 ° C. °. The evolution of the nanofibers deposition process via electrofinning, as occurred in other cases, showed, in the same figure, a reduction in AC values (due to the higher diameter fiber compaction), followed by a further increase in AC as a consequence. refinement of nanofiber diameter and more uniform deposition. Compared to pure PCL and DEXA nanofibers deposited on starch substrates, the addition of SULFA allowed higher AC values.

[078] In the case of hydrothermally obtained starch substrates, as well as some substrates based on starch and LDPE blends (Figure 24), the CA found tend to increase progressively with the time of deposition. This behavior suggests that the presence of silver sulfadiazine alters the spinability characteristics of the system (probably increasing the electrical conductivity), favoring the earlier stabilization of the electrophony process and the production of more refined and better distributed nanofibers on the substrates.

[079] Surfaces decorated with PCL nanofibers containing silver sulfadiazine also exhibited low contact angle hysteresis values (below 5 °), virtually independent of substrate types and deposition times. These results indicate that the topography / chemistry of the modified surfaces favors low degrees of adhesion to water droplets that are ideal for self-cleaning behavior.

Example 4- Characterization by Scanning Electron Microscopy (SEM) [080] Scanning Electron Microscopy (SEM) images of the samples were obtained using the Scanning Electron Microscopy (FEI, INSPECT S50) and Metalizing Machine (SPI Suplies). Sputter coater) from the UFMG Metallurgical Engineering department with 5nm gold deposition. We also used the 5nm carbon deposition (Leica EM SCD 500) and the FEG Scanning Electron Microscope with FIB - Quanta FEG 3D FEI Nanofabrication System from the UFMG Microscopy Center.

2 Aminoethyl Polystyrene (MPS) Microspheres: The MPS microscopically presented a different image than expected. Initially, it was expected that the spheres would be in a random, monolayer arrangement that would form topographic patterns for gout support. However, SEM images (Figures 10, 11 and 12) showed the formation of microstructures based on microsphere-rich regions and poor regions on them. Such segregation must have occurred due to the low affinity of the microspheres with the more hydrophilic substrate. The microsphere-rich regions also presented a texture due to the individual presence of each sphere, which eventually generated a complex structure with well-pronounced topographic hierarchical degrees.

PCL and Silver Sulfadiazine Nanofibers (PCL / SULFA): [082] The SEM images shown in Figures 25 and 26 show the distribution of PCL / SULFA nanofibers on starch substrates produced by the thermomechanical method. Thicker fibers can be observed for 2, 3 and 4 minutes. These images allow the application of the combined Cassie-Baxter / Wenzel models, visualized by the nanofiber spacing able to define sufficient space to accumulate air and assist the nanofibers in supporting the drop of water. It can be observed again that as the deposition time increases, the fiber diameter decreases. This is due to the stability that the system acquires over time, since a difference in tension is applied during the production of these nanofibers that requires balance, so the thicker nanofibers are the ones initially produced.

Example 5- Characterization by Optical Microscopy (MO) [083] Samples were observed on the Leica optical microscope (MO), model dm2500m, with a 10x magnification, and with attached image recording device. The images were made in order to verify the arrangement of fibers and spheres on the surface of the samples.

Spongilite: [084] Optical microscopy showed the good distribution of spongilite fibers on the surface of the starch sample produced by the hydrothermal process, Figure 4, with 10% occupancy, Figure 5, with 1% and Figure 6, with 0.5%.

Example 6- Characterization by Infrared Absorption Spectroscopy (FTIR) [085] Infrared absorption spectroscopy (FTIR) analysis between 4000 and 400cm‘1 was performed at LEPCom. The analysis was performed on a Nicolet model 6700 equipment equipped with Fourier Transform and ATR accessory. The crystal used was ZnSe and the number of scans was 32 with 4crrf1 resolution. FTIR analysis was performed to confirm the nature of the different chemical compositions present on the surfaces of the materials.

PCL and dexamethasone nanofibers (PCL / DEXA): [086] The dexamethasone FTIR spectrum has characteristic infrared absorption bands which are: 3000-2800cm'1 associated with CH2 groups; 1750-1720cm-1 and 1659cm-1 associated with the aliphatic ester and ketone carbonyl groups respectively; ~ 896cm ~ 1 due to axial stretch of group C-F. Figure 22 (a) shows the infrared spectra (FTIR) for the PCL nanofiber sample, which correspond to the infrared absorption bands at 2949cm -1 and 2865cm -1. Fig. 22 (b) shows the infrared absorption bands. absorption at 1659cm'1 and 896cm1 identifying the presence and preservation of the chemical aspect of dexamethasone incorporated in PCL nanofibers

PCL and silver sulfadiazine nanofibers (PCL / SULFA): [087] Typical infrared absorption bands reported for PCL and identified in Figure 27 (a) are: 2949cm "1 and 2865cm1 asymmetric and symmetrical CH2 stretch respectively; 1727cm "1 carbonyl stretch; 1293cm "1 CO and CC stretch in the crystalline phase; 1240cm'1 asymmetric COC stretch; 1170cm'1 symmetrical COC stretch. The 1293cm" 1 band is assigned to the crystalline phase and its intensity can evaluate the crystallinity changes in PCL nanofibers incorporated with the drug. The silver sulfadiazine FTIR spectrum has characteristic bands at 1549 and 837cm -1 associated with the vibration of the C = C bond of the pyrimidine ring and the aromatic ring to be substituted and the band at 1597cm ~ 1 associated with the vibrational deformation of the phenyl-conjugated phenyl structure. NH2 group. The absorption bands at 1597, 1549 and 839cm "1 in Figure 27 (b) identify the presence of silver sulfadiazine incorporated into the PCL nanofibers suggesting that the chemical aspect of the drug was preserved during electrophony.

Example 7- Characterization by Atomic Force Microscopy (AFM) [088] The surfaces of the samples decorated with PCL nanofibers were analyzed by atomic force microscopy (Park, inc.), Model XE-70 belonging to LEPCom. The images were constructed by scanning the surfaces via intermittent probe contact mode.

PCL Nanofibers: [089] Figure 17 shows an AFM image of the hydrothermally produced starch sample after two minutes of deposition of PCL nanofibers. It is possible to notice the presence of micro and nano structures and some regions with fiber clusters, which also helped in the decoration of the surface, in the formation of valleys that are occupied by air (considering the association of Cassie-Baxter / Wenzel models).

Claims (19)

1. Surface modification process of polymeric films comprising the following steps: (a) heating of the polymeric film from 40 to 190 ° C; B) Dispersion of microcomponent as particles and fibers (oxides, hydroxides, minerals among others) in solvent such as water, alcohols, acetone, toluene, tetrahydrofuran, etc. at room temperature for 1 min; C) Scattering the dispersion in the heated film; D) Packaging of the product in desiccator. Surface modification process of polymeric films according to claim 1, step "a", characterized in that the polymeric film is preferably thermoplastic starch (TPS) obtained via hydrothermal or thermomechanical. Surface modification process of polymeric films according to claim 1, step "b", characterized in that the microcomponent is preferably spongylite, hollow glass spheres or 2-aminoethyl polystyrene (MPS) microspheres. Surface modification process of polymeric films according to claim 1, step "b", "c" and "d", and claim 3, characterized in that the spongilite is dispersed in ethyl alcohol in the proportions of 0.1, 10, 50 and 100% of spongilite in relation to the occupation of the surface of the film, to be dripped on the surface of the film until the alcohol evaporates and to be desiccated for 24 hours. Surface modification process of polymeric films according to claim 1, step "b" and "c", and claim 3, characterized in that the hollow glass spheres are dispersed in ethyl alcohol in the proportions of 5 and 10%. spheres in relation to the film surface occupancy and dripping onto the film surface until the alcohol evaporates. Surface modification process of polymeric films according to claim 1, step "b" and "c", and claim 3, characterized in that the 2-aminoethyl polystyrene (MPS) microspheres are dispersed in the proportions of 10 to 5 % of microspheres in relation to the total surface occupation of the film, with the aid of tip ultrasound, for 10 minutes in ethyl alcohol and dripped on the film surface until alcohol evaporation. Modified polymer characterized in that it is obtained from the process described in claims 1, 2, 3 and 4 with thermoplastic starch (TPS) obtained hydrothermally or thermomechanically as a polymeric film and with spongylite as a microcomponent. Modified polymer characterized in that it is obtained from the process described in claims 1, 2, 3 and 5 with thermoplastic starch (TPS) obtained hydrothermally or thermomechanically as a polymeric film and hollow glass beads as a microcomponent. Modified polymer characterized in that it is obtained from the process described in claims 1, 2, 3 and 6 with thermoplastic starch (TPS) obtained hydrothermally or thermomechanically as a polymeric film and with 2-aminoethyl polystyrene (MPS) microspheres as a microcomponent. . A polymeric film modification process comprising the following steps: A) Dissolving in solvents such as water, alcohols, acetone, toluene, tetrahydrofuran, acids, trifluoroethylene polymer such as polycaprolactone, poly (lactic acid) and its copolymers, starch chitosan, polyhydroxybutyrate and their copolymers with or without the addition of components under magnetic action; B) Transfer of the solution to a syringe and insertion into the electrospinning apparatus; C) Application of a potential difference; D) Sample collection; E) Deposition on the surface of the film. Surface modification process of polymeric films according to claim 10, step "e", characterized in that the polymeric film is preferably thermoplastic starch (TPS) obtained via hydrothermal or thermomechanical. Surface modification process of polymeric films according to claim 10, step "a", characterized in that the nanocomponent is preferably polycaprolactone nanofibers (PCL), polycaprolactone nanofibers (PCL) with addition of dexamethasone and polycaprolactone nanofibers ( PCL) with the addition of silver sulfadiazine. Surface modification process of polymeric films according to claim 10, steps "a", "b", "c", "d" and "e", characterized by molar mass polycaprolactone (PCL) nanofibers 80,000 to 90,000g / mol are dissolved in a formic acid / acetic acid (1: 1) mixture under magnetic stirring for 4 hours at room temperature in a 3.0 mL / h flow rate electrospinning apparatus, under + 25 / 0KV voltage, inside electrospinning chamber temperature of 25.3 ° C and humidity of 58%, collected on an 8 cm diameter automated rotary collecting disc (90 rpm) and deposited on the starch and starch / PE with deposition time variation of 2, 3, 4 and 5 minutes. Surface modification process of polymeric films according to claim 10, steps "a", "b", "c", "d" and "e", characterized by molar mass polycaprolactone (PCL) nanofibers 80,000 to 90,000g / mol are dissolved in a mixture of formic acid / acetic acid (1: 1) and dexamethasone (DEXA) under magnetic stirring for 4 hours at room temperature in a 3% flow rate electrospinning apparatus. , 0 mL / h, under + 25 / 0KV voltage, inside electrospinning chamber temperature of 25.3 ° C and humidity of 58%, collected on 8 cm diameter automated rotary collector (90 rpm) and deposited on starch and starch / PE samples with deposition time variation of 2, 3, 4 and 5 minutes. Surface modification process of polymeric films according to claim 10, steps "a", "b", "c", "d" and "e", characterized by molar mass polycaprolactone (PCL) nanofibers 80,000 to 90,000g / mol are dissolved in a mixture of formic acid / acetic acid (1: 1) and silver sulfadiazine (SULFA) under magnetic stirring for 4 hours at room temperature in a flow rate electrospinning apparatus. of 3.0 mL / h, under + 25 / 0KV voltage, inside electrospinning chamber temperature of 25.3 ° C and humidity of 58%, collected on 8 cm diameter automated rotary collecting disc (90 rpm) and deposited on starch and starch / PE samples with deposition time variation of 2, 3, 4 and 5 minutes. Modified polymer characterized by being obtained from the process described in claims 10, 11, 12 and 13 with thermoplastic starch (TPS) obtained hydrothermally or thermomechanically as polymeric film and with PCL nanofibers as nanocomponent. Modified polymer characterized by being obtained from the process described in claims 10, 11, 12 and 14 with thermoplastic starch (TPS) obtained hydrothermally or thermomechanically as a polymeric film and with PCL nanofibers with addition of dexamethasone as nanocomponent. Modified polymer characterized by being obtained from the process described in claims 10, 11, 12 and 15, with thermoplastic starch (TPS) obtained hydrothermally or thermomechanically as a polymeric film and with PCL nanofibers with silver sulfadiazine addition as nanocomponent . Use of modified polymers characterized in that they are obtained from the processes defined in claims 1 to 6 and 10 to 15 and are used for the manufacture of hydrophobic or superhydrophobic surface products, particularly packaging, medical / pharmaceutical products and products. of the textile industry.