바이오 기반 다이올을 이용한 폴리에스터아마이드 수지 개발

학위논문 (석사)-- 서울대학교 대학원 : 공과대학 재료공학부, 2019. 2. 안철희.The growing interest in renewable resource-based feedstock chemicals and polymeric materials has promoted numerous studies in bio-sources. According to the current global production of bioplastics in 2017, PET and polyamide are the top two engineering plastics worldwide. PET exhibits disadvantages due to relatively low physical strength and Tg. One way to modify PET to yield a higher Tg and better mechanical properties is to combine polyesters and polyamides. Poly(ester-amide)s (PEAs) have a good melt processability and a less water absorption known as a serious drawback of polyamide. For these reasons, PEAs are attracting widespread interests in many researchers. Though much effort has been involved into PEAs, most of the existing studies have increased biodegradability by polymerizing aliphatic PEAs and to the best of our knowledge, only a few studies have been conducted on PEAs for engineering plastics containing aromatic residues. In this study, for the development of bioplastics having mechanical properties superior to PET, monomers for the polymerization of PEAs were selected and synthesized based on amino acids and dimethyl esters which are non-edible bio-based materials. In the initial stage of the research, polymerization was attempted by synthesizing monomers of terephthalamide structure in order to have better mechanical properties. Monomers of terephthalamide structure had a high melting point due to excellent packing between the benzene ring and hydrogen bonding due to the presence of adjacent amide bonds. By this reason, monomers were decomposed when the polymerization proceeded at the melt-process, which made monomers of terephthalamide structure not suitable as monomers for thermal bulk polymerization. To overcome this problem, the amide bond was introduced into the aliphatic diol to lower the melting point and dimethyl terephthalate having a low melting point was selected as the counterpart of polymerization that led to drastically lowering the melt-process temperature for thermal bulk polymerization. The thermal stability of every monomer and oligo-polymer synthesized by solution polymerization was evaluated. Four different diols were selected for thermal bulk polymerization based on the sufficient difference in their melting points and decomposition temperatures. In the same process as PET, thermal polymerization was successfully completed for all four diols and analyses were conducted by selecting the representative polymer synthesized with PSuP diol and DMT. Through FT-IR spectroscopy, it was confirmed that the polymer had both an ester bond and an amide bond. The model polymer having a weight average molecular weight of about 55,000 and a polydispersity index of 1.28 was polymerized. Thermal analysis showed that the glass transition temperature was nearly twice as high as that of PET, which enabled various fields to utilize PEAs in applications requiring much wider temperature range. Based on the results, the establishment of further experimental direction on how to change the internal carbon chain length of the diol will proceed.재생 가능한 자원을 기반으로 한 화학 물질 및 고분자 재료에 대한 관심이 높아지면서 바이오 기반 물질들에 대한 많은 연구들이 진행되고 있다. 전 세계 난분해성 바이오 플라스틱 생산량 1,2 위는 폴리에틸렌테레프탈레이트와 폴리아마이드이다. 폴리에틸렌테레프탈레이트는 낮은 물성과 유리전이온도를 가지는 명확한 단점을 보유하고 있다. 이러한 단점을 보완하기 위한 방법 중 하나로 폴리에스터와 폴리아마이드를 결합한 폴리에스터아마이드를 중합하고자 하는 연구들이 진행되고 있다. 현재까지, 지방족 단량체를 이용한 폴리에스터아마이드 중합에 관한 연구 외에 방향족 단량체를 포함시킨 중합에 관한 연구는 거의 진행되고 있지 않다. 폴리에틸렌테레프탈레이트 보다 우수한 물성의 바이오 플라스틱 개발을 위해 본 연구에서는 비식용 바이오 기반 물질인 아미노산과 다이메틸에스터를 기반으로, 폴리에스터아마이드 중합을 위한 단량체를 선정 및 합성하고 이의 합성을 진행하였다. 연구 진행 초기에는, 보다 우수한 물성을 보유하고자 테레프탈아마이드 형태의 단량체를 합성하여 중합을 시도하였다. 테레프탈아마이드 형태의 단량체는 벤젠 고리 사이의 우수한 적층성과 반복되는 아마이드 결합으로 인한 수소 결합으로 인해 높은 융점을 보유하여 용융 공정으로 중합을 진행 시 분해되는 현상이 발생하기 때문에 열 중합을 위한 단량체로 부적합하다고 판단하였다. 이를 개선하고자 아마이드 결합을 지방족 다이올에 도입시켜 융점을 낮추고, 중합 대응물로 융점이 낮은 다이메틸테레프탈레이트를 선정하여 열 중합을 위한 용융 공정 온도를 대폭 낮추었다. 중합에 사용되는 모든 단량체와 용액 중합을 통해 합성한 올리고폴리머의 열적 안정성을 평가하여 녹는점과 분해 온도가 충분한 차이를 나타내는 4 종류의 다이올을 선정하였고, 이를 이용한 열 중합을 진행하였다. 폴리에틸렌테레프탈레이트와 동일한 공정으로, 4 종류의 다이올 모두 열 중합을 성공적으로 진행 완료하였고 대표 중합체를 선정하여 여러 분석을 진행하였다. 적외선 분광법을 통해, 해당 고분자가 에스터 결합과 아마이드 결합 둘 모두를 보유함을 확인하였고, 젤 투과 크로마토그래피 분석을 통해 중량평균분자량이 약 55,000, 다분산지수는 1.28의 값을 가지는 고분자가 중합되었음을 확인하였다. 열 분석을 통해 유리전이온도가 폴리에틸렌테레프탈레이트에 비해 2 배 가까이 높음을 확인하여 훨씬 더 넓은 사용 온도 범위가 요구되는 분야에서의 활용 가능성을 확보하였다.Abstract i Contents v List of Tables and Figures viii 1. Introduction 1 2. Experiments 4 2.1. Materials 4 2.2. Synthesis of Monomers with Terephthalamide Structure 5 2.2.1. Ethanolamine-DMT-Ethanolamine (EDE) Trimer 5 2.2.2. Propanolamine-DMT-Propanolamine (PDP) Trimer 5 2.2.3. DMT-Cadaverine-DMT (DCD) X-mer 6 2.2.4. MCCB-Cadaverine-MCCB (MCM) Trimer 7 2.2.5. Tyramine-TCL-Tyramine (TTT) Trimer 9 2.2.6. Ethanol-Tyramine-TCL-Tyramine-Ethanol Pentamer 9 2.3. Synthesis of Aliphatic Diol Monomers Containing Amide Bonds 12 2.3.1. Dimethyl Malonate Based Diol (EME/PMP) 12 2.3.2. Dimethyl Succinate Based Diol (ESE/PSP) 13 2.3.3. Dimethyl Adipate Based Diol (EAE/PAP) 13 2.3.4. Dimethyl Suberate Based Diol (ESuE/PSuP) 14 2.4. Solution Polymerization of Poly(ester-amide)s 17 2.4.1. Polymerization with Terephthalamide Structure Monomers 17 2.4.1.1. EDE Trimer 17 2.4.1.2. MCM Trimer 17 2.4.1.3. TTT Trimer 19 2.4.2. Polymerization with Aliphatic Diol Monomers 19 2.5. Thermal Bulk Polymerization of Poly(ester-amide)s 20 2.5.1. Polymerization with Terephthalamide Structure Monomers 21 2.5.1.1. EDE/PDP Trimer, EG, and DMT Terpolymer 21 2.5.1.2. DCD X-mer Based Poly(ester-amide)s 24 2.5.1.3. Acetylation of TTT Trimer for Polymerization of Poly(ester-amide)s 26 2.5.2. Polymerization with Aliphatic Diol Monomers 26 2.5.2.1. Large Scale Polymerization for Preparation of Tensile Test Specimens 28 2.6. Characterization 29 2.7. Thermal Properties 30 2.8. Mechanical Properties 31 3. Results and Discussion 32 3.1. Synthesis of Monomers and Polymerization with Terephthalamide 32 3.2. Analyses of Causes of Failure in Thermal Bulk Polymerization and Establishment of New Experimental Direction 36 3.3. Synthesis of Tailor-made Diols Containing Amide Bonds and Thermal Properties of Diols 40 3.4. Polymerization of Poly(ester-amide)s with Tailor-made Diols 43 3.5. Establishment of Further Research Direction through Representative Compound Selection and Various Analyses Thereof 46 4. Conclusion 57 5. References 59Maste

A case of unexpected adjacent tooth extrusion after implant fixed prosthetic treatment, who had undergone mandibular resection and reconstruction due to ameloblastoma

Ameloblastoma is a benign odontogenic epithelial tumor with high recurrence rate and requires extensive resection of the surrounding tissue and reconstruction of defect site. Because of the anatomical limitation of the reconstruction site, prosthetic treatment with implants is the first recommendation. This is a case of prosthetic restoration of the reconstruction site with implant fixed prosthesis in patient who underwent mandibular resection and iliac bone reconstruction due to ameloblastoma. However 14 months after completion of implant prosthesis, adjacent natural tooth erupted unexpectedly, resulting in 1mm infra-occlusion occurred including posterior implant prosthesis and anterior natural teeth. In adults, implant infra-occlusion may occur due to residual growth after placement of the maxillary anterior implant. But this case, hypo-occlusion of molar implant and open bite of anterior natural teeth is occurred due to extrusion of adjacent tooth, is rare. Thus we report the treatment process including orthodontic treatment with intrusion of the posterior tooth, and investigate the causes of sudden, unexpected tooth extrusion.ope

Importance of immediate surgical intervention and antifungal treatment for rhinocerebral mucormycosis: a case report

Rhinocerebral mucormycosis (RCM) is an opportunistic, potentially life-threatening fungal disease. This infective disease invades not only the facial sinuses, but also the maxilla, zygoma, and rhino-cerebral structures with a massive destruction of the facial skeletons and soft tissue. This disease progresses within various underlying diseases, such as diabetes mellitus, hematologic malignancy, renal failure, and systemic immunodepression. The relationship between mucormycosis and these underlying conditions have been discussed extensively in the literature. The authors studied 6 cases of RCM diagnosed by a tissue biopsy and treated at the department of oral and maxillofacial surgery, from 1997 to 2012. Patients were treated with several kinds of surgical interventions and antifungal agents, and their clinical & radiological signs, underlying conditions, surgical methods, and outcomes were analyzed.ope

Low-grade osteosarcoma arising from cemento-ossifying fibroma: a case report

Cemento-ossifying fibromas are benign tumors, and, although cases of an aggressive type have been reported, no cases of cemento-ossifying fibroma transforming into osteosarcoma have been documented previously. Low-grade osteosarcoma is a rare type of primary bone tumor, representing 1%-2% of all osteosarcomas. A 45-year-old female patient was diagnosed with cemento-ossifying fibroma, treated with mass excision several times over a period of two years and eight months, and followed up. After biopsy gathered because of signs of recurrence, she was diagnosed with low-grade osteosarcoma. The patient underwent wide excision, segmental mandibulectomy, and reconstruction with fibula free flap. The aim of this report is to raise awareness of the possibility that cemento-ossifying fibroma can transform into osteosarcoma and of the consequent necessity for careful diagnosis and treatment planning.ope

Development of Unsteady Preconditioned Multi-Phase Roem and Ausmpw+ Schemes

본 논문은 2015년도 미래창조과학부의 재원으로 NSL사업(NRF-2014M1A3A3A02034856)과 민ㆍ군협력 기술사업(Civil-Military Technology Cooperation Program)의 지원을 받아 작성되었습니다.OAIID:RECH_ACHV_DSTSH_NO:420160000004648010RECH_ACHV_FG:RR00200003ADJUST_YN:EMP_ID:A001138CITE_RATE:FILENAME:비정상_예조건화_기법을_적용한_다상유동_RoeMAUSMPW+_수치기법··.pdfDEPT_NM:기계항공공학부EMAIL:[email protected]_YN:FILEURL:https://srnd.snu.ac.kr/eXrepEIR/fws/file/696b8222-7074-43e7-8294-9499eb9c0b74/linkCONFIRM:

Reduction of superior-lateral intact mandibular condyle dislocation with bone traction hook

Lateral and superior-lateral dislocations of the intact condyle are a rare complication, following traumatic insult to the mandible. We report an unusual case of a 54-year-old male patient who experienced both types of dislocations of the intact condyles with symphysis fracture following a road-traffic accident. Under general anesthesia, conventional manipulation was unsuccessful in relocating the condyles into the glenoid fossa. After applying a percutaneous traction force, using a bone traction hook placed at the sigmoid notch, the displaced intact mandibular condyles were repositioned, and the symphyseal fracture was finally reduced and fixed. The mouth opening was within normal limits, and favorable occlusion was confirmed one month postoperatively. To our knowledge, this is the first case of dislocation of both intact condyles--associated with symphysis fracture--being reduced with bone traction hook.ope

Bisphosphonate 복용환자에서 임플란트를 식립하는 것이 정당한가?

ope

Prognosis of gingival squamous cell carcinoma diagnosed after invasive procedures

Gingival squamous cell carcinoma (SCC) has a relatively poor prognosis, because differential diagnoses of periodontitis and osteomyelitis are difficult to exclude. As such, gingival SCC is usually diagnosed late, following invasive procedures such as extraction or curettage. The purpose of this study was to classify gingival SCC patients into two groups according to the location of their primary lesion: dentate and edentulous, and to determine the appropriate treatment strategy by comparing clinical and histological features as well as treatment results. The medical records of 76 patients diagnosed with gingival SCC and treated at one institute from 1 January 1993 to 31 December 2007 were reviewed. The overall 5-year survival rate was 60.7%, and the mean survival was 98 months. Factors affecting survival included bone invasion of the primary lesion (p = 0.035), neck node metastasis (p = 0.001), and local recurrence (p = 0.000). The results suggest that more aggressive treatment, such as setting a broad surgical field and enforcing preventive neck dissection, can improve outcome, although they are associated with increased rate of cancer bone invasion and neck metastasis in patients diagnosed with cancer after receiving invasive procedures.ope

Considerations and Protocols in Virtual Surgical Planning of Reconstructive Surgery for More Accurate and Esthetic Neomandible with Deep Circumflex Iliac Artery Free Flap

Purpose: The reconstruction of mandibular defects poses many difficulties due to the unique, complex shape of the mandible and the temporomandibular joints. With development of microvascular anastomosis, free tissue transplantation techniques, such as deep circumflex iliac artery (DCIA) flap and fibular free flap (FFF), were developed. The DCIA offers good quality and quantity of bone tissue for mandibular segmental defect and implant for dental rehabilitation. Virtual surgical planning (VSP) and stereolithography-guided osteotomy are currently successfully applied in three-dimensional mandibular reconstruction, but most use FFF. There are only a few articles on reconstruction with the DCIA that assess the postoperative results. Methods: Three patients admitted during a five month period (April of 2013 to August of 2013) underwent resection of mandible and DCIA musculo-osseous reconstruction using a VSP and stereolithographic modeling and assessment of outcomes included technical accuracy, esthetic contour, and functional outcomes. Results: This technique yielded iliac bone segment with excellent apposition and duplication of the preoperative plan. Flap survival was 100 percent and all patients maintained preoperative occlusion and contour. Conclusion: Based on our experience, we offer considerations and logically consistent protocols by classification of mandibular defects, and demonstrate the benefits in VSP and stereolithographic modeling of mandibular reconstructive surgery with DCIA flap.ope

Sectioned images and surface models of a cadaver for understanding the free vascularised anterior rib flap

Background: The purpose of this study is to describe the vascularised anterior rib flap on sectioned images and surface models using Visible Korean for medical education and clinical training in the field of mandibular reconstructive surgery. Materials and methods: Serially sectioned images of the thorax were obtained from a cadaver. Significant structures in the sectioned images were outlined and stacked to create a surface model. Results: The PDF file (8.45 MB) of the assembled models can be downloaded for free from our website (http://vkh.ajou.ac.kr/Products/PDF/Vascularized_anterior_rib_flap.zip). In this file, important anatomical structures related to the vascularised anterior rib flap can be examined in the sectioned images. All surface models and stereoscopic structures of the vascularised anterior rib flap are expressed in real time. Conclusions: We hope that these state-of-the-art sectioned images, outlined images, and surface models will help students and trainees gain a better understanding of the anatomy of the vascularised anterior rib flap.ope