Enhancing the Polymerization Properties of Plastics Using a Bio-Engineered Nanoscale Catalyst System

INTRODUCTION
Plastic waste is one of the most important problems globally due to its accumulation in the environment and its non-biodegradability, which causes plastic pollution. Therefore, an innovative solution to this pollution had to be found through bioplastics, a material that is environmentally friendly due to its low carbon footprint, sustainability, and low toxicity, in addition to its high degradation rate. It is a suitable alternative to plastics manufactured from fossil fuels [1-3]. In addition to plastic waste accumulation, environmental pollution caused by contaminants in water [4-6] and air [7-9] has become a major global concern. Industrial activities, agricultural runoff, fossil fuel combustion, and improper waste disposal release hazardous substances into aquatic and atmospheric environments, negatively affecting ecosystems and human health. Water pollution threatens aquatic organisms and reduces water quality, while air pollution contributes to respiratory diseases, climate change, and environmental degradation [5, 6]. Consequently, the development of sustainable and eco-friendly technologies has become essential to reduce pollution and promote environmental protection.
Interest in the biosynthesis of nanoparticles has emerged due to the significant risks associated with synthesizing them through physical and chemical methods, which lead to the production of toxic chemicals on the surface of the nanoparticles, in addition to their high manufacturing costs and the need for reducing agents, stabilizers, and strong reducing agents that pose health and environmental risks [10-17]. Recent advances in microfluidic technology have provided powerful tools for biological and biomedical research by enabling precise control of cellular microenvironments. These technologies offer significant advantages, including reduced reagent consumption, enhanced experimental reproducibility, and the ability to closely mimic physiological conditions [18-20]. 
To address these significant issues, the potential for green synthesis using plants and algae has been explored, as they contain a range of active compounds such as phenolic compounds, flavonoids, and glycosides, which can be used to synthesize nanoparticles more precisely and safely [21, 22]. This synthesis has achieved remarkable progress in terms of cost, ease of synthesis, environmental friendliness, and the fact that it does not require high heat, pressure, or energy [23].
Nanoparticles are characterized by their high stability and biocompatibility, with sizes ranging from 1 to 100 nanometers and various shapes, including spherical, cubic, triangular, rod-shaped, and others [24]. They possess novel chemical and physical properties, such as increased reaction rates, and exhibit magnetic and electrical properties that differ from those of the original material [25]. 
Algae of various types are effective tools in the synthesis of silver nanoparticles, such as blue-green algae [26] and green algae such as Ulva [27]. These algae are considered living factories, and Chara vulgaris is a safe source for their production [28]. Chara is characterized by its diverse forms and is found in many regions worldwide; it is a freshwater alga found in ponds and rivers [29] It is capable of environmental adaptation and treating heavy metal pollution such as arsenic [30] and is considered a promising bio-resource that opens new horizons for environmental sustainability.

MATERIALS AND METHODS
Sample Collection and Macroscopic Identification
The sample was collected from the Zammar region in Iraq. After confirming the sample’s purity, the algae were identified macroscopically by preparing temporary slides of the sample and examining them under a light microscope at 40X magnification to determine the genus and species of the algae. It was then washed and cleaned of dust, dried in an oven at a temperature of 40-50°C for 3-4 days, ground using a porcelain mortar, and stored in tightly sealed containers until use.

Preparation of the hexane extract from the algae
After collection, drying, and grinding, a Soxhlet apparatus was used according to the method described by [31] to prepare the hexane extract, fifty grams of the powder were placed in a filter paper folded into a funnel shape, and 500 mL of hexane were added. The sample was left submerged in the solvent for 24 hours, after which the Soxhlet apparatus was operated at 55°C for 24 hours. Upon completion of the extraction process, the product was transferred to a rotary evaporator, and the extract was transferred to a small, sealed container until use in the production of plastic polymers. 

Identification of the components of the hexane extract using gas chromatography-mass spectrometry (GC-MS)
GC-MS was used to identify the components of the extract at the University of Samarra, College of Applied Sciences, using a Shimadzu GCMS-QP2010 Plus instrument manufactured by Shimadzu (Japan). Forty microliters of the extract were taken and diluted to a total volume of 5 mL with ethanol. The injector was set to 2 microliters of the diluted sample using an (Inert Cap 1 capillary column a non-polar column bonded with 100% dimethylpolysiloxane) with a length of 30 meters. The carrier gas was helium at a flow rate of 14.5 mL/min. The oven thermal program began at 60°C with a split ratio of 2:1, and the temperature was held at this level for two minutes. then the temperature was raised at a rate of 30 °C per minute until reaching 180 °C, where it was held for 3 minutes; subsequently, the temperature was raised to 220 °C and maintained for 4 minutes, with a total retention time of 18 minutes. Mass spectra were recorded at an energy of 72 eV and a mass range of 900–500 m/z. The chemical compounds extracted from the sample were identified by comparing the resulting spectra with mass spectra in the libraries available in the instrument software [32]. 

Production of a Polymer from a Moss Hexane Extract 
Diol Reduction 
100 mL of the hexane extract was taken, and 10 mL of tetrahydrofuran (THF) and 178 mg of Lithium Aluminum Hydride (LiAlH4) were added to it. The mixture was cooled to 0°C, then heated to boiling for one hour, and left on a stirrer for 3 days at room temperature. The reaction was terminated by adding (2 mL of distilled water and 0.5 mL of 2 M sodium hydroxide solution). The mixture was evaporated at 50°C, and 10 mL of chloroform was added to recrystallize the product.

Polycondensation Reaction
The product prepared in the first reaction was left for one hour, then heated to 80°C, and the temperature was increased by 10°C every 30 minutes until it reached 120°C, after which it was placed on a stirrer for 24 hours. After stirring was complete, 0.1 mL of a solution (0.05 mL of Ti (OBu)₄ catalyst in 20 mL of toluene) was added to the resulting mixture, and the temperature was raised to 200 °C for 3 hours [33].

Production of Nanoparticles (Ag NPs, Fe₂O₃ NPs)
10 g of dried algal powder was taken and 100 mL of deionized distilled water was added to it in a 250 mL glass beaker. The mixture was heated to 60°C with magnetic stirring for one hour, after which it was centrifuged at 1000 g for 15 minutes, then filtered using Whatman No. 1 filter paper [28, 34]. Next, 10 mL of the aqueous extract was taken and gradually added to 90 mL of a salt solution containing both silver nitrate (Ag NO₃) at a concentration of 0.05 M and ferric chloride (FeCl₃) at a concentration of 0.1 M (prepared by mixing the metal salt with deionized distilled water) and heated to 40°C under magnetic stirring until the solutions changed color, which is a preliminary indicator of the success of the nanoparticle production process. The solutions were then centrifuged for 15 minutes at 1000 rpm to separate the nanoparticles. The precipitate was washed with deionized water and then with ethanol in a 1: 3, with centrifugation to remove impurities. The precipitate was dried in an oven at 40°C for 12–24 hours to obtain the nanoparticles in powder form. They were stored in opaque containers to protect the silver nanoparticles from light and were characterized using a number of techniques [35].

Characterization of Iron and Silver Nanoparticles 
Biologically synthesized iron and silver nanoparticles were characterized using a UV-visible spectrophotometer at wavelengths ranging from (200 to 700 nm), A scanning electron microscope (SEM) was also used to image and determine the size and shape of the iron and silver nanoparticles, in addition to X-ray diffraction (XRD) to determine the crystalline nature of the nanoparticles. Fourier transform infrared (FTIR) spectroscopy was also used, to identify the functional groups that contributed to the preparation of iron and silver nanoparticles [36].

Effect of the Nanocatalyst on the Polymerization Process
To improve the condensation polymerization process and obtain advanced properties for the resulting plastic polymer, the conventional catalyst (LiAlH4) with 0.05 g of a catalyst (ChCl-based DES/AgNPs catalyst) synthesized from silver nanoparticles (AgNPs), and the nanocatalyst was added to the reaction mixture using ultrasound for 15 minutes prior to addition to ensure its proper distribution [37, 38].

Characterization of the polymer using Fourier Transform Infrared Spectroscopy (FTIR)
The properties of the polymer were characterized at the College of Science, University of Mosul, using a Bruker FTIR spectrometer. 

RESULTS AND DISCUSSION
Morphological Diagnosis of the Algae
The sample was Morphologically Diagnosed as shown in Fig. 1 using a light microscope and based on its morphological characteristics through the classification references for algae. It was found that the alga is Chara vulgaris, is a green alga.The algae is characterized by a vertical axis attached to the substrate via root-like structures, and a stem consisting of nodes and internodes. From an evolutionary perspective, it is considered a link between algae and bryophytes [39].

Diagnosis of the components of the hexane extract using gas chromatography-mass spectrometry (GC-MS)
GC-MS results in Fig. 2 and Table 1 show that the hexane extract is rich in unsaturated fatty acids such as (linoleic acid)9,12-ctadecadienoic acid (20.39%), which acts as a natural plasticizer, increasing the polymer’s flexibility [40]. It also contains long-chain hydrocarbons such as tetracosane and hexadecane, which increase the polymer’s hydrophobic properties. Additionally, l-(+)-Ascorbic acid 2,6-dihexadecanoate (29.74%) protects the polymer from thermal degradation during manufacturing [41].

Diagnostic Methods for Iron and Silver Nanoparticles
Color Detection
When the aqueous extract of Chara algae was added to both ferric chloride and silver nitrate solutions and mixed thoroughly for 30-45 minutes at 40°C, a color change was observed in each, indicating the production of nanoparticles. The reaction between ferric chloride and the aqueous extract of the algae changed the solution’s color from orange to brown, a preliminary indication of iron ion reduction and the production of iron oxide nanoparticles. Meanwhile, the reaction between the algal extract and silver nitrate changed the solution’s color from transparent to purple, confirming the production of silver nanoparticles, as shown in Fig. 3. This color change may be due to the presence of biochemical compounds identified in the Chara algal extract Table 1. These active compounds play a significant role in nanoparticle production, as they stabilize and reduce the nanoparticles, allowing for their dispersion and homogeneous distribution in solutions [42, 43].

UV-VIS analysis 
The UV of Fe2O3NPs in Fig. 4A show the clear absorption edge at wavelength of 350nm These results are consistent with the findings of Subhashini et al. 2018 [44], who reported that the absorption peak of iron oxide nanoparticles lies within the wavelength range of 300-400 nm ,This strong absorption in the UV region is attributed to charge transfer electron transitions, specifically the transfer of electrons from oxygen orbitals (2p) to iron orbitals (3d), that indicate the formation of iron oxide nanoparticle in uniform size.
The optical energy gap was calculating by Tauc’s relation by plotting the relationship between (ahV)2 and the photon energy (hv). In Fig. 4B show the energy gap of Fe2O3NPs was 1.67 electron volte this result is considered ideal for narrow gap of semi-conductors compared to iron oxide in bulk form. This value reflects the “Quantum Confinement Effect” resulting from reducing the size of the particles to the nanoscale [45, 46].
The curve in Fig. 5A show the clear peak at 450nm, this peak cause by the phenomenon of surface Plasmon resonance which is a collective vibration of free electrons on the surface of silver particles when expose to light. The presence of peak 450nm indicate that the particles are medium in size as a red shift of peak towards longer wavelength indicate increase in size, while its presence in this range confirms the successful formation of silver nanoparticles [47]. The energy gap of AgNPs in Fig. 5B was calculating by Tauc’s relation by plotting the relationship between (ahV)2 and the photon energy (hv). The energy gap of AgNPs was 2.05ev so this value is low as a compered to bulk silver reflecting the quantum effect and the distinctive optical properties of the prepared nanostructure.

FESEM analysis
The FESEM of Fe2O3NPs in Fig. 6 show a structure composed of tightly packed, irregular in shape and it show some aggregation, where the nanoparticles fused together this pattern is very common in nonmetal oxide is often attributed to reaction conditions or the nature of the attraction between the particles. The mean particle size was 52nm, the particles size of nanoparticles is between (20-100) it was within the nanoscale (less than 100nm) which confirms the success of the preparation method [48].
The FESEM of AgNPs in Fig. 7 show the homogenous composition of spherical particles indicating the efficiency of the preparation process in controlling crystal growth. There is a slight tendency for the particles to aggregate into clusters, a natural behavior for metallic nanoparticles to reduce their high surface energy. The mean particle size of AgNPs was 41nm, the particale size of nanoparticales is between (20-90) it was within the nanoscale [49].

XRD analysis
The XRD result of Fe2O3NPs in Fig. 8 show the hematite phase of Fe2O3 with the hexagonal crystal system. All the diffraction peaks at levels (110), (006), (202), (211) and (300) matching with JCPDS card 33-0664. The display of the peaks also confirmed the nanoscale nature of the material, with the pattern being free of any peaks belonging to impurities, indicating the success of the preparation process and the acquisition of a pure and stable phase [50]. Fig. 9 shows the XRD analysis of AgNPs that show the distance bands at specific diffraction angles corresponding to the (111) and (311) which are matching to JCPDS card 04-0783. The silver nanoparticles have a face centered cubic crystal structure. While the secondary peaks attributed to the organic materials of algae extract use in reduction and precipitation process [51, 52].

FTIR analysis
The FTIR analysis of Fe2O3NPs in Fig. 10 shows that the spectrum conforms the formation of iron oxide mineral network and the presence stabilizing functional groups the 676 peak is the important peak and represent the stretch vibration of the (Fe-O) bond. The 851 peak this is due to the bending vibration of (Fe-O-H) bond appear as a result of the interaction of particle surface with moisture or hydroxyl groups. The bond (1052) represents the stretch vibration of the (C–O) bond, resulting from the residue of organic compounds that coated the iron oxide during preparation. The bond (1394): is due to the bending vibrations of the (C–H) bonds or carboxyl groups. The bond (1640): represents the (C=O) or (C=C) vibrations; these bonds play a role in binding the nanoparticles to the catalysts in the extract. The broad bond (3368): a strong, broad peak due to the stretch vibration of the hydroxyl group (O–H), indicating the presence of water molecules adsorbed on the oxide surface or strong hydrogen bonds [50, 53]. Fig. 11 shows the FTIR analysis of AgNPs, this spectrum is considered evidence of a bio capsulation process where the bands resulting from the plant extract that coated the silver atoms are visible. The bands in 3406, 3257 are responsible for reducing silver ions from (Ag+) to (Ag0), band in 2921 represent the stretch vibration of an aliphatic bond indicate of carbon chain from the extract biomolecules.  Bond (1767) is a sharp bond belonging to the carbonyl group (C=O), indicating the presence of esters or organic acids that increase the stability of the particles. Bond (1610) is due to aromatic (C=C) bonds or protein vibrations (Amide I), confirming the presence of a protein layer that protects the particles from agglomeration. Bonds (1238 and 1029) are due to stretch vibrations of the (C–O) bond, indicating the presence of alcohols and carbohydrates from the extract acting as surface stabilizers. Loose bonds (665 and 612) indicate the interaction between the silver surface and the surrounding organic groups [54].

FTIR Polymer Diagnostics
The results in Fig. 12 confirm the success of the polymerization process using the catalyst (Ti (OBu)₄), as evidenced by the appearance of several absorption bands, including the 1722 cm-1. This band is attributed to the carbonyl group C=O, which is a product of the polymerization of the organic bonds in the extract, in addition to the C-O bonds in the 1000–1300 cm⁻¹ range for ester compounds, and the presence of bands resulting from the vibration of the C-H bond at (2851–2920 cm⁻¹), which contributes to the increased hydrophobicity of the resulting polymer. The broad band at 3427 cm⁻¹ is attributed to the vibration of the hydroxyl group (OH), which provides sites for enzymatic and microbial activity [55]. The appearance of C=C bond peaks at 1637 cm⁻¹ and at 3010 cm⁻¹ for the C=C-H bond indicates that the polymer retains a proportion of unsaturated bonds, which are flexible, slip-pronechains. 
The spectrum shown in Fig. 13 reveals the nano-catalyzed polymer compound, where a broad band appears at 3393 cm⁻¹; the reason for its broadening compared to the initial spectrum is the formation of a network of hydrogen bonds between the active surface of the high-energy nano-catalyst and the active groups of the polymer. The absence of the C=O carbonyl peak at 1722 cm⁻¹ was observed, along with the appearance of a peak at 1416 cm⁻¹ accompanied by overlapping peaks (1505–1558 cm⁻¹). This is attributed to the participation of the oxygen double bonds in the carbonyl group in stabilizing and confining the nanoparticles, as well as the appearance of new, sharp absorption peaks at the low-frequency ranges of 643 cm⁻¹ and 525 cm⁻¹ 507 cm⁻¹ and 427 cm -1 are attributed to oxygen–metal bond vibrations (Ag–O), which strongly indicates the incorporation of the nanocatalyst into the biopolymer [56].

CONCLUSION
The results indicated the successful green and sustainable synthesis of iron oxide (Fe2O3NPs) and silver nanoparticles (Ag NPs) using the aqueous algal extract. Furthermore, the efficiency of their incorporation and stabilization within the biopolymer prepared from the hexane extract, characterized by its content of active compounds and fatty acids, was demonstrated. Colorimetric tests and comparisons of the secondary particles confirmed a color change, an important physical indicator proving the reduction of metal ions and their transformation into stable secondary particles. UV-Vis spectroscopy results confirmed the successful reduction and formation of nanoparticles, a clear absorption edge for iron oxide appeared at 350 nm with an energy gap of 1.6 ev while the surface plasmon resonance peak for silver appeared at 450 nm with an energy gap of 2.05 ev. FTIR spectroscopy results reinforced this conclusion by showing the role of the extract’s organic compounds (such as carbohydrates, proteins, and carbonyl bonds) as reducing agents and surface stabilizers that coated the nanoparticle and prevented random aggregation.  X-ray diffraction (XRD) results confirmed the high purity and stable precipitation of the prepared crystalline phases without the appearance of impurities. The formation of the hematite phase with the hexagonal crystal system and the iron oxide particles with the face-centered cubic crystal structure of the silver nanoparticles was confirmed. Scanning electron microscopy (FESEM) images revealed that the iron oxide particles possess a tightly packed and irregularly shaped structure with an average particle size of 52, while the silver particles exhibited normal behavior to reduce their high surface energy with an average size of 41, confirming the success of the preparation method in obtaining ideal nanoscale sizes. In addition, spectroscopic examinations proved the success of the polymerization process using the catalyst (Ti (OB)4) and the formation of ester chains. When the nanoparticles were incorporated into the biopolymer, the FTIR spectrum showed a broadening and shift in the hydroxyl bond band, indicating the formation of a strong, interlocking hydrogen bond network between the polymer’s active groups and the active surface of the nano catalyst. This was supported by the emergence of new, sharp vibrations of the oxygen-metal (Ag-O) bond, demonstrating the achievement of efficient physical and chemical integration and stabilization of the nanoparticles within the prepared biopolymer network in a shorter time. Also, the ChCl-based DES/AgNPs catalyst gave excellent results compared to the first catalyst, confirming the superiority of green synthesis of silver nanoparticles synthesized from algal extract.

CONFLICT OF INTEREST
The authors declare that there is no conflict of interests regarding the publication of this manuscript.