pH/temperature‐responsive poly(dimethylaminoethyl methacrylate) grafted κ‐carrageenan copolymer: Synthesis and physicochemical properties

Abstract

κ‐Carrageenan‐graft‐poly(dimethylaminoethyl methacrylate) (CRG‐g‐PDMA) was synthesized via free‐radical copolymerization under microwave irradiation. 13C‐Nuclear magnetic resonance spectroscopy (13C‐NMR), fourier‐transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) methods were used for characterization of the CRG‐g‐PDMA structure. The effect of reaction variables including the concentrations of the initiator and dimethylaminoethyl methacrylate (DMA) as well as the microwave irradiation time and power on graft ratio and conversion was investigated, and their highest values were obtained to be 179 and 76%, respectively. The lower critical solution temperatures (LCSTs) of the CRG‐g‐PDMA copolymers were determined at various pH conditions, and their value in distilled water was found as 47°C. Besides, the swelling capacity of the copolymers under different pH levels was investigated and it was seen that the swelling capacity of the copolymer increased with the decrease in the pH value of the medium. The CRG‐g‐PDMA copolymer exhibited excellent swelling performance in acidic pH conditions and possessed responsiveness to pH and temperature stimuli.

Swelling and Viscoelastic Properties of Cellulose-Based Hydrogels Prepared by Free Radical Polymerization of Dimethylaminoethyl Methacrylate in Cellulose Solution

“…These vibration bands are more pronounced in samples 1-3 and 1-5, indicating that the content of PDMAEMA increased relative to samples 1-1. In addition, a characteristic band of CH 2 vibrations at 1457 cm −1 with a strong intensity also indicates the presence of PDMAEMA [45]. In the lower part of the spectrum, the bands at 780 and 750 cm −1 [45], which can be attributed to PDMAEMA, are more pronounced in the samples that had a higher content of DMAEMA in the initial reaction mixture (1-3 and 1-5 samples).…”

“…The presence of PDMAEMA was revealed by the band at around 1724 cm −1 , which can be assigned to carbonyl group vibrations [40,43]. Several other bands indicate the presence of PDMAEMA in the prepared samples, such as the vibrational bands at 2824 and 2769 cm −1 [43][44][45], which are characteristic of the CH 3 group attached to the tertiary amine. These vibration bands are more pronounced in samples 1-3 and 1-5, indicating that the content of PDMAEMA increased relative to samples 1-1.…”

Ca2+ İyonları ile Çapraz Bağlı Sodyum Aljinat/-Karagenan Kürelerden Nifedipinin Kontrollü Salımı

“…Yüksek pH'larda ise -COOH grupları kısmen iyonlaşır ve oluşan karboksilat anyonları arasında oluşan elektrostatik itme kuvvetinden dolayı şişme artmaktadır (LeeYuan 2000). -KRG polimerleri yüksek pH'larda şişme eğilimindedir (GeyikIşıklan, 2020a;Işıklan vd., 2011). Şişme oranının artması ilacın kolay difüze olmasına neden olmuştur ve ilaç salımı artmıştır.…”

“…Doğal polimerlerin tercih sebepleri arasında biyouyumlu olmaları, toksik olmamaları, molekül büyüklüğünün kontrol edilebilmesi ve parçalanabilir olmaları gelmektedir (Babu vd., 2006). Karagenanlar Rhodophyceae sınıfı kırmızı deniz yosunlarından elde edilen, sülfat grubu içeren galaktoz türevi monomer yapılarından oluşmaktadır (GeyikIşıklan, 2020a;Stanley, 1987). Karagenanların farklı tiplerde oluşması yapılarında bulunan ester sülat gruplarının konumuna, sayısına ve içerdikleri 3,6 anhidro-D-galaktoz miktarına bağlı olarak değişmektedir.…”

“…Yapıda bulunan sülfat grubunun birim başına tekrarlanması karagenanın çeşidini belirlemektedir. Tekrarlama sayısı bir ise , iki ise  ve üç ise  olarak adlandırılmaktadır (GeyikIşıklan, 2020a). Yapısında bir sülfat grubu bulunduran kappa karagenanlar, α-(1-4)-3,6 anhydro-D-galaktoz ve β-(1-3)-D-galaktoz-4-sülfat disakkarit gruplarından meydana gelmektedir (GeyikIşıklan, 2020b).…”