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Synthesis and Characterization of Block Copolymers Derived from Germanium Dicarboxylic Acids and Aminopropyl Terminated Polydimethylsiloxanes

Thesis Info

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External Link

Author

Gill, Rohama

Program

PhD

Institute

Quaid-I-Azam University

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2009

Thesis Completion Status

Completed

Subject

Chemistry

Language

English

Link

http://prr.hec.gov.pk/jspui/handle/123456789/409

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727441415

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Block copolymers having polyamide with a trichlorogermyl pendant, (-CO- R''-CO–NH-Ar-NH-CO-R''-CO-) x as hard segment and aminopropyl-terminated polydimethylsiloxane H 2 N(CH 2 ) 3 SiO(CH 3 ) 2 (CH 3 ) 2 SiO) y Si(CH 3 ) 2 (CH 2 ) 3 NH 2 ], (PDMS) as the soft segment of general formula [(-CO-R''-CO-HN-Ar-NH) x -CO-R′- CO-NH(CH 2 ) 3 SiO(CH 3 ) 2 (Me 2 SiO) y Si(CH 3 ) 2 (CH 2 ) 3 NH 2 ] n , [n = 4.37 to 1175.0; x = 5 to 8; y = 360] where R′ = CH 2 CH(CH 2 GeCl 3 ); CH 2 CHGeCl 3 CH 2 ; CH 2 CH(GeCl 3 ); CH(CH 3 )CH(GeCl 3 ); CH(CH 3 )CH(GeCl 3 ) and Ar = C 6 H 4 ; (-C 6 H 3 -CH 3 ) 2 ; (-C 6 H 3 - OCH 3 ) 2 ; 2,5-(CH 3 ) 2 -C 6 H 2 and C 6 H 4 -O-C 6 H 4 were prepared by polycondensation reaction. A series of trichlorogermyl-substituted dicarboxylic acids of general formula HOOC-R-COOH where R = CH(CH 2 GeCl 3 )CH 2 - (2), -CH(GeCl 3 )CH 2 - (3), -CH 2 CH(GeCl 3 )CH 2 - (1), - –CH(CH 3 )CH(GeCl 3 )- (4) – CH(GeCl 3 )CH(CH 3 ) (5) were synthesized by the hydrogermylation reaction of unsaturated acids such as itaconic, trans-glutaconic, fumaric, mesaconic and citraconic acid with HGeCl 3 which was produced in situ by the reaction of GeO 2 with 37% HCl in presence of NaH 2 PO 2 .H 2 O. The synthesized trichlorogermyl substituted dicarboxylic acids were characterized by melting point, elemental analysis, FTIR, 1 H NMR and 13 C NMR. X-ray crystal structures of the trichlorogermyl substituted itaconic acids (1) and trans-glutaconic (2) were analyzed to show supramolecular structures in which central Ge atom in each of these structures is four-coordinated with a slightly distorted tetrahedral geometry. The trichlorogermyl substituted dicarboxylic acids were then converted into their respective acid chloride using dry, distilled SOCl 2 and condensed with slightly less than the required stoichiometric amounts of various para-substituted aromatic diamines dissolved in dry THF in the presence of an organic base Et 3 N under strict inert conditions to yield respective chloro terminated polyamide which were copolymerized in situ with aminopropyl-terminated polydimethylsiloxane (PDMS) dissolved in dry THF to obtain various series of seventeen new block copolymers PA 1 to PA 17 These block polymers were structurally characterized by elemental analysis, FT-IR, 1 H NMR, solid state 13 C NMR and molecular weight determination. Their molecular weights as determined by Laser Light Scattering technique were found in range 1.71×10 5 to 331×10 5 g/mol . The thermal stability of these copolymers was xivinvestigated by using various thermal analyses techniques such as TGA and DSC. These block copolymers show two Tgs, at ca -120 o C and the other between 350 o C to 400 o C indicating presence of soft component of PDMS and hard component polyamide with average decomposition temperature at 500 o C. TG-FTIR studies indicate that initial decomposition of these block copolymers starts with the evolution of CO. The pyrolysis of these polymers under inert conditions was done and the GCMS studies of the gases thus evolved revealed the presence of the oligomeric cyclic products of general formula [(CH 3 ) 2 SiO] n where n 3-7 and the polyamide fragments. Scanning electron microscopy (SEM) was used to study the surface morphology. Thermodynamic and kinetic parameters such as Ea, ∆H, ∆S, and n were calculated from Tg curves using Horowitz/Metzger methods. The values of activation energy so obtained fall in the range of 38.30 kJ/mol to 76.12 kJ/mol. Hydrogen bonding and inter-chain linkage give them increased activation energy and high stability. Due to the presence of polar site of polyamide block the copolymers absorb 5-17% moisture when soaked in water, using standard procedures at room temperature. The block copolymers were used for the covalent assembly of Layer by Layer (LbL) multilayers adopting a dipping technique for the deposition onto pre- activated Silicon or quartz substrates. Primarily, by using PDMS with a molar mass of about 2,500 g/mol and about 27,000 g/mol, the conditions (such as concentration of polymers, dipping time, rinsing etc.) for covalent layer-by-layer assembly were optimized to the point of identifying reaction conditions for this surface reaction that led to the construction of multilayers with a linear growth increment with respect to the number of layers chemisorbed and embedding of macromolecules with only 2 functional end-groups. As LbL multilayer assemblies are formed by the alternate deposition of polymers, therefore in the present study poly(ethylene-alt-maleic anhydride (PEMA) was used along with PDMS. Polyethylenimine (PEI) layer was deposited onto the substrate as the precursor layer. Thus the LbL film architecture was PEI(PEMA/PDMS)n where n = number of layer pairs deposited. The thickness of each layer pair was measured using an ellipsometer, while AFM, SAXR and UV Spectroscopy were also employed for the characterization of LbL nanofabricated multilayers. Aminopropyl terminated PDMS having only two functional groups have been successfully adsorbed onto PEMA utilizing the LbL technique resulting into multilayer buildup.
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الحاج عبدالقیوم

الحاج عبدالقیوم
۱۵؍ نومبر ۲۰۰۱؁ء کو الحاج عبدالقیوم صاحب کا انتقال ہوگیا، وہ کلکتہ کے ایک مشہور ہوٹل کے مالک تھے، اﷲ تعالیٰ نے انہیں دولت کے ساتھ، قوم و ملت کا درد، دین داری اور ہر طبقے میں مقبولیت عطا کی تھی، کلکتہ ہی نہیں ملک کے بھی علمی و تعلیمی اداروں کو ان سے بڑا فیض پہنچتا تھا۔
یتیم خانہ اسلامیہ کلکتہ کے عرصے تک صدر رہے، اس زمانے میں یتیموں کی پرورش اور کفالت میں کوئی دقیقہ باقی نہیں رکھا، اسلامیہ ہسپتال کے بھی برسوں صدر رہے کلکتہ کے مسلمانوں کے سب سے قدیم ادارہ انجمن مفید السلام کے اصل کرتا دھرتا جناب سید محمد صلاح الدین صاحب تھے جو جناب سید صباح الدین عبدالرحمان صاحب کے حقیقی چچا تھے، ان کے کلکتہ چھوڑنے کے بعد انجمن کے حالات درہم برہم ہوئے تو الحاج عبدالقیوم صاحب نے اس کو اپنے ہاتھ میں لے لیا اور اپنے رفیق الحاج غلام رسول صاحب کی معاونت سے اس کے حالات درست کئے، وہ ۱۹۹۲؁ء تک انجمن کے صدر رہے، اور اپنے بعد کلکتہ کے ایک مقبول اور ہر دل عزیز شخص جسٹس خواجہ محمد یوسف کو انجمن کا صدر بنوایا۔
ہندوستان کے جن علمی و تعلیمی اداروں سے ان کا زیادہ تعلق تھا ان میں دارالمصنفین، ندوۃ المصنفین اور دارالعلوم ندوۃ العلما خاص طور سے قابل ذکر ہیں، مولانا مفتی عتیق الرحمان صاحب کے وہ بڑے قدرداں تھے اور ندوۃالمصنفین کی اعانت اور سرپرستی فرماتے تھے، دارلعلوم ندوۃ العلما کی بھی امداد فرماتے، دارالمصنفین کے سابق ناظم جناب سید صباح الدین عبدالرحمان مرحوم بھی الحاج عبدالقیوم صاحب کے بڑے مداح تھے اور کلکتہ تشریف لے جاتے تو جن لوگوں سے التزاماً ملاقات کرتے ان میں یہ اور حاجی غلام رسول مرحوم بھی تھے۔
عبدالقیوم صاحب اہل علم کے بڑے قدرداں تھے علما اور دانش وروں...

تفسیر جلالین میں اسرائیلی روایات کا تجزیاتی مطالعہ

Holy Quran is the most sacred scripture bestowed by Allah Almighty upon his bellowed prophet Muhammad (PBUH). Unlike other scriptures, Allah Almighty himself took the responsibility of safety and safe custody of the Holy Quran. That is why, despite passage of more than 1400 years, the Holy Quran remained intact, wordwise as well as meaningwise and will remain intact till the end of the world. Such a unique status of the Holy Quran could not be tolerated by the enemies of Islam and Prophet of Islam. Therefore, they decided to present Holy Quran as a defective document before its readers. For this purpose, they chose to highlight and exploit the short and abbreviated incidents, described by the Holy Quran, under the term of “Muthashalihat”, by adding and narrating false, nonsense and most astonishing stories, just to divert attention of the readers from the basic learning of Holy Quran, towards un-realistic and bogus stories. Accordingly majority of the readers have shown great interest in these stories, which fall under the title of Israiliat Unfortunately, the said stories are included in dozens of Translations Tafaseer of the Holy Quran. In order to acquaint readers of the actual status of Israiliat, the undersigned has started working on the subject. Since Tafseer-e-Jalalain is included in the Syllabus of Maddaris and being taught for the last many years, therefore, I have chosen the same in the first instance, and pray Allah Almighty to help me out in completing my assignment.

Synthesis of Biocompatible Self-Assembling Amphiphiles for Vesicular Drug Delivery Applications.

Oral route is preferred for drug administration due to convenience in dose administration, lack of pain, effectiveness and increased patient compliance. Drug’s decreased aqueous solubility, gastric instability, enzymatic degradation, decreased biological membrane permeability, P-gp based drug efflux, first pass metabolism, mucus membrane barrier and early clearance from the body are various factors leading to poor oral bioavailability and less therapeutic efficacy of orally administered drugs. Conventional drug dosage forms have not been effective in addressing these issues. Recently, nanotechnology has got much scientific interests in various fields. The biomedical applications of nano-carriers have been the subject of recent interests due to their evident role in addressing the above mentioned drug related issues. Amphiphilic molecules are capable of self-assembling into vesicles upon their contact with aqueous media. They are able to dissolve both hydrophilic and lipophilic drugs either in their interior aqueous compartment or exterior lipid bilayer respectively. Self-assembling amphiphilic molecules like phospholipids, nonionic surfactants, block copolymers and peptides are widely used for designing vesicular nanocarrier drug delivery systems. They are physically stable, economic, efficient and release the loaded drug in a sustain manner, thus leading to enhance oral bioavailability with better clinical outcomes. The current study was designed for the synthesis of four different biocompatible amphiphiles for nano-vesicular drug delivery applications. They were synthesized in neucleophilic substitution reactions by reacting hydrophilic moieties (Creatinine and Pyridoxine) with lipophilic acyl chlorides and aliphatic alkyl bromide respectively. The Vitamin E based amphiphile was synthesized in multi step reaction to introduce polar hydrophilic moiety in lipophilic alpha tocopherol (Vitamin E). These synthetic amphiphiles were characterized through 1H NMR and xii Mass spectrometric analytical techniques. All the amphiphiles were subjected to biocompatibility studies and their nano-vesicular drug delivery applications were investigated using model poorly aqueous soluble drugs i.e. Clarithromycin, Azithromycin and Amphotericin B. All the amphiphiles were less cytotoxic, hemo-compatible and non-toxic to animals. They were capable of forming nano-vesicles of almost spherical shape with homogenous size distribution. The drug loaded vesicles exhibited increased surface negativity and loaded increased amounts of the selected model drugs. They released the loaded drugs in a controlled pattern at various pHs when tested for in-vitro release. Amphiphiles based drug loaded vesicles demonstrated higher storage stability and retained maximum drugs upon incubation with simulated gastric fluid. Invivo bioavailability of the selected drugs was increased in a controlled manner in rabbits upon their oral administration in the form of amphiphiles based nano-vesicles. Results of the current study authenticates biocompatibility of these synthesized amphiphiles and their effectiveness for oral drug delivery of poor aqueous soluble drugs. The results are interesting and provide a scientific base for their use in vesicular drug delivery systems. The results will open new research areas for formulation scientists to investigate their membrane permeability mechanisms with ultimate increased therapeutic efficacy of loaded drugs.