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중합공정에 따른 PBA/PMMA Composite Latex 모폴로지의 연구
이기창 ( Ki Chang Lee ),최현성 ( Hyeon Seong Choe ) 한국고무학회 2011 엘라스토머 및 콤포지트 Vol.46 No.1
2.1 ㎛입자경의 단분산 PBA seed를 이용한 2단계 분산중합을 seeded batch process 와 seeded semi-continuous process를 이용하여 다양한 형태의 PBA/PMMA composite 미립자를 제조하였다. Batch process의 경우 PBA/PMMA composite 입자의 모폴로지는 중합 분산매인 methanol/water 비와 중합 2단계에서의 PBA seed/MMA단량체의 비에 따라 크게 영향을 받으며, methanol/water 중합분산매중 물의 량이 증가함에 따라, 그리고 중합 2단계에서 MMA단량체량이 증가함에 따라 PBA와 PMMA간의 상분리현상이 심화되어 구형의 입자로부터 egg, snowman, confetti, peanut와 같은 비구형의 PBA/PMMA composite 입자들이 제조되었다. Semi-continuous process의 경우 단량체 부가시간을 조절함으로서 PBA/PMMA composite 입자의 모폴로지가 변함을 발견하였고 특히, 단량체의 결핍된 조건하에서 구형의 PBA(코어)/PMMA(쉘) composite 라텍스가 제조되었다. The various types of PBA/PMMA composite latexes were prepared by 2.1 ㎛PBA seeded batch and seeded semi-continuous dispersion polymerization. The morphology of the PBA/PMMA composite latexes by seeded batch process was found to be closely dependant on the weight ratios of methanol/water in polymerization medium and of PBA seed/MMA at the second stage. In general, egg, snowman, confetti, peanut-like nonspherical composite latex particles were formed with increasing amount of water and MMA as a result of the occurrence of the phase separation between PBA seed and PMMA. The morphology of the PBA/PMMA composite latexes by seeded semi-continuous process was controlled by the addition time of MMA, especially, spherical shaped core(PBA)/shell(PMMA) composite latex particles were prepared under the monomer-starved condition at the second stage.
문용주 ( Mun Yong Ju ),이지현 ( Lee Ji Hyeon ),최현성 ( Choe Hyeon Seong ),윤석권 ( Yun Seog Gwon ),김한욱 ( Kim Han Ug ),임철완 ( Im Cheol Wan ) 대한피부과학회 2004 대한피부과학회지 Vol.42 No.3
Merkel cell carcinoma is an uncommon malignancy of the skin that was first described by Toder in 1972 and occasionally found concurrent with other malignancies such as squamous cell carcinoma, basal cell carcinoma or, as in the present study, with Bowen`s disease. We report a unique case of Merkel cell carcinoma coexisting with Bowen`s disease on the left forearm of a 42-year-old man who had a past history of multiple Bowen`s disease. The tumor was excised and the specimen was examined histopathologically. The tumor cells exhibit trabecular, cord-like arrangement in the dermis, partly extending into subcutaneous tissue without involvement overlying epidermis, where Bowen`s disease lesion was absent but the peripheral patch area exhibit Bowen`s disease. The tumor cells in the dermis were positive for neuron-specific enolase and chromogranin. This is the first report of a case of Merkel cell carcinoma associated with Bowen`s disease in Korea. (Korean J Dermatol 2004;42(3):309~312)