Doğal ve sentetik polimer esaslı/sürfaktan ve sürfaktan gruplu nano tanecik katkılı çapraz bağlı malzemelerin fizikokimyasal özelliklerinin incelenmesi
Investigation of the physicochemical properties of crosslinked materials based on natural and synthetic polymers/supported with surfactant group nanoparticles
- Tez No: 1011121
- Danışmanlar: PROF. DR. CANDAN ERBİL
- Tez Türü: Doktora
- Konular: Kimya, Polimer Bilim ve Teknolojisi, Chemistry, Polymer Science and Technology
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 2026
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Lisansüstü Eğitim Enstitüsü
- Ana Bilim Dalı: Kimya Ana Bilim Dalı
- Bilim Dalı: Kimya Bilim Dalı
- Sayfa Sayısı: Belirtilmemiş.
Özet
Poli(N-[3-(dimetilamino)propil] metakrilamid) (PDMAPMAAm) hidrojellerinin düşük mekanik dayanımı, performans malzemesi olarak kullanımlarını sınırlamaktadır. Bu çalışmada, reaktif olmayan katyonik bir yüzey aktif madde ve yüzey aktif madde benzeri nanokompozit şablon görevi gören setiltrimetilamonyum bromür (STAB) ve trimetil stearil amonyum montmorillonit (TMSA-MMT) varlığında serbest radikal çözelti polimerizasyonu kullanılarak, PDMAPMAAm bazlı üç boyutlu bir matriksin morfolojisi ve mekanik performansı değiştirilmiştir. Başlatıcı olarak potasyum persülfat (KPS) ve çapraz bağlayıcı olarak N,N′-metilenbisakrilamid (BIS) kullanılarak, üç farklı monomer konsantrasyonu ve çeşitli STAB konsantrasyonları ile 3 boyutlu (3D) matriks polimerizasyonları oluşturulmuştur. STAB kaynaklı faz geçiş davranışı ve sıkıştırma modülünün etkilerini incelemek için mekanik testler, polarize optik mikroskopi (POM) ve X-ışını kırınımı (XRD) kullanılmıştır. STAB ve TMSA MMT varlığında sentezlenen 3D polimerik matriks, (PDMAPMAAm) hidrojellerine kıyasla sıkıştırma modülünde yaklaşık on kat artış gösterdi (yaklaşık 3,0'dan yaklaşık 30,0 kPa'ya), POM ve XRD analizleri ise STAB'ın polimerizasyon sırasında lameller ve heksagonal mezofazların oluşumundan sorumlu olduğunu doğruladı. Ek olarak, yenilenebilir ve toksik olmayan, fenolik hidroksil grupları içeren fenilpropan ünitelerinden oluşan bir biyopolimer olan lignin (L) kullanılarak, petrol türevli fenol-formaldehit (PF) yapıştırıcıların yeşil bir alternatif lignin-formaldehit (LF) reçinesi geliştirilmiştir. Sabit potasyum persülfat konsantrasyonu (0,1 mol L⁻¹), farklı alkali koşullar (NaOH konsantrasyonları 1,24, 2,80 ve 5,50 mol L⁻¹), lignin içerikleri (1,60 ve 6,80 mol L⁻¹) ve reaksiyon süreleri (2 ve 5 saat) kullanılarak, Elbs persülfat oksidasyonu yoluyla reaktif lignin üretilmiştir. Yüksek fenolik hidroksil içeriği (3,25–3,45 mmol g⁻¹) ve katı madde içeriği (%38,9) nedeniyle, asit-baz titrasyonu, ¹H NMR ve gravimetrik çalışmalara göre, ideal reaktif lignin, 5,50 mol L⁻¹ NaOH içinde 2 saat boyunca 6,80 mol L⁻¹ lignin kullanılarak oluşturulmuştur. Molekül ağırlığı dağılımları, termal özellikleri ve hidrojen bağı etkileşimlerini incelemek için GPC, FTIR, DSC, TGA, 13C ve ¹H NMR kullanılmıştır. Ek olarak, PF bazlı ağaç kompozitlerine kıyasla, LF ve LF/TMSA-MMT sistemleri, Çin Ulusal Standardı'nın (GB/T 14732–2006) gereksinimlerini karşılayan, belirgin şekilde daha düşük serbest formaldehit konsantrasyonları (sırasıyla %0,25 ve %0,06) göstermiştir. Genel olarak, bu bulgular, kontrollü supramoleküler yapılandırma ve kimyasal modifikasyon tekniklerinin, lignin bazlı ahşap yapıştırıcıların ve polimerik 3D matriksin mekanik ve çevresel performansını başarıyla iyileştirebileceğini göstermektedir.
Özet (Çeviri)
Crosslinked polymeric network with high water absorption capacities is known as 3D polymeric matrix (hydrogels). Their structural and functional characteristics, including as high water content, biocompatibility, and porosity, make them suitable in a variety of biotechnological applications, such as drug delivery systems, tissue scaffolds, contact lenses, and separation membranes. To employ them in physiological body fluids, they must have high swelling degrees and mechanical strength. However, a high water retention capacity may lead to low mechanical properties. Some structural changes, such as the addition of a comonomer to the main polymer chain, the use of a different crosslinker, and the addition of nanoparticles during 3D matrix synthesis, can be produced to overcome the weakness in the mechanical properties of synthetic matrix. Because of their liquid crystal behaviors, amphiphilic compounds known as surfactants offer a lot of potential. Amphiphilic compounds consist of two components: a non-polar tail group with a hydrophobic hydrocarbon chain and a polar head group with an ionic character in solution. Amphiphilic compounds fall into three categories: anioic, cationic, and nonionic. For instance, sodium dodecyl sulfat (SDS) is an anionic surfactant, and N-cetyl-N,N,N, trimethylamonium bromide (STAB) is a cationic surfactant. Amphiphiles create a monolayer between water and air at very low concentrations. These orderly structures transform into agglomerates in water as concentration rises. Meanwhile, the hydrophilic portions of surfactants interact with water molecules while the hydrophobic portions of surfactants migrate away from them. We refer to this event as“micelle formation.”Surfactant self-assemblies are dependent on their critical micelle concentrations. Surfactant molecules are randomly distributed as monomers below the the critic concentrations, while they form micelles above it. Packaging parameter is another crucial factor in micelle production. Micelles might be spherical, cylindrical, planer, or inverted depending on the packaging parameters. Amphiphiles above critic concentrations exhibit spherical micelle isotropic dispersion. Micelles develop into cylindircal micelles as surfactant concentration rises, producing a hexagonal or lamellar arrangement. When creating 3D matrix, surfactants can be utilized as a template. Lyotropic liquid mesophases are the name given to these clusters in the surfactants. Surfactants can be used as a template during the synthesis of a 3D matrix to control its mechanical strength and swelling behavior. According to the findings reported in the literature, crosslinked 3D matrix porosity can be regulated by these ordered structures. Low mechanical strength of (PDMAPMAAm) 3D synthetic matrix limits their use as performance materials. This study used free-radical solution polymerization in the presence of STAB and TMSE-MMT, which function as a nonreactive cationic surfactant and surfactant-like nanocomposite template, to modify the morphology and mechanical performance of a PDMAPMAAm-based 3D matrix. Using potassium persulfate (KPS) as initiator and N,N′-methylenebisacrylamide (BIS) as crosslinker, three monomer concentrations and various STAB concentrations were used to create 3D matrix polymerizations. Mechanical testing polarized optical microscopy (POM), and X-ray diffraction (XRD) were used to examine the effects of STAB-induced phase transition behavior and compression modulus. The templated 3D matrix showed nearly a tenfold increase in compression modulus compared to nontemplated systems (from ~3.0 to ~30.0 kPa), while POM and XRD analyses verified that the STAB is responsible for the formation of lamellar and hexagonal mesophases during polymerization. On the other hand, the development of synthetic resins, natural adhesives have begun to be replaced by urea-formaldehyde (UF), phenol-formaldehyde (PF) and melamine-formaldehyde (MF) resins, which have reduced water retention capacity and improved physical/chemical resistance and can be cured by heat or catalyst effect. Higher quality, longer lasting and more durable panels can be prepared with synthetic resins used as adhesives. However, the use and development of these types of resins are limited due to their dependence on petroleum resources, non-renewable nature, and toxicity. Therefore, in the last 30 years, there has been significant interest in both academic and industrial fields in the combined use and development of natural and synthetic resins. With the increasing environmental and health awareness worldwide, several different approaches have been investigated, particularly for the direct use of soy protein-based adhesives or the development of new formulations using plant-based sources such as tannins and lignins. Lignin is a three-dimensional polymer composed of randomly linked phenylpropane (C9) units via etheric and condensation-formed 5–5 and β-1 bonds such as β–O–4, β–5, β–β, and α-O-4. Ether bonds in the lignin structure are the dominant bonds between three types of phenolic units, including coniferyl, sinapyl and p-coumaryl alcohols, which contain numerous functional groups such as ortho-aromatic hydroxyl and aliphatic hydroxyl groups. Many studies have been conducted in the literature on the use of lignin instead of phenol in phenol formaldehyde resins, but the low reactivity of lignin has shifted research towards increasing lignin reactivity. Lignin can react with formaldehyde at the unsubstituted C9 units at position 5 and form hydroxylated species like phenol. These species can then combine with phenol or other lignin units via methylene bridges to form polymers. The main disadvantages of using lignin in these types of resins are their low reactivity due to their complex chemical structure and the lower number of hydroxyl groups compared to equivalent amounts of phenol. Potassium persulfate (KPS) is one of the initiators frequently used in free radical polymerizations by generating radicals through the effect of temperature or with the help of a redox pair. KPS is also a strong oxidant that can be used in the oxidation of phenols and anilines. When used with phenolic compounds in strongly alkaline environments, it causes the hydroxylation of phenol. This system, defined as Elbs persulfate oxidation, has not been used on lignin before. Results showed that the reactivity of lignin increases by introducing additional hydroxyl groups into its phenolic units, based on the Elbs persulfate oxidation reaction. Additionally, a sustainable lignin-formaldehyde (LF) resin was developed in parallel as a green substitute for petroleum-derived phenol-formaldehyde (PF) adhesives using lignin (L), a renewable and non-toxic biopolymer made of phenylpropane units containing phenolic hydroxyl groups. Using a constant potassium persulfate concentration (0.1 mol L⁻¹), different alkaline conditions (NaOH concentrations of 1.24, 2.80, and 5.50 mol L⁻¹), lignin contents (1.60 and 6.80 mol L⁻¹), and reaction periods (2 and 5 h), reactive lignin was produced via Elbs persulfate oxidation. Because of its high phenolic hydroxyl content (3.25–3.45 mmol g⁻¹) and solids content (38.9%), the ideal L was created at 6.80 mol L⁻¹ lignin in 5.50 mol L⁻¹ NaOH for 2 hours, according to acid–base titration, ¹H NMR, and gravimetric studies. GPC, FTIR, DSC, TGA and ¹³C NMR were used to characterize molecular weight distributions, thermal characteristic and hydrogen-bonding interactions. In comparison to traditional PF/wheat flour adhesives (8.10 and 3.2 MPa), plywood panels bonded with LF resin containing 10 weight percent trimethyl stearyl ammonium–montmorillonite (TMSA-MMT) showed dry and wet shear strengths of 6.15 and 2.2 MPa, respectively. Additionally, in comparison to PF-based benchmarks, LF and LF/TMSA-MMT systems demonstrated noticeably lower free formaldehyde concentrations (0.25% and 0.06%), satisfying the Chinese National Standard's requirements (GB/T 14732–2006). In conclusion, these findings show that controlled structuring and chemical modification techniques can successfully improve the mechanical and environmental performance of biobased adhesives and polymeric 3D matrix.
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