생유기화학 (Bioorganic Chemistry) Synthetic Polymer-III ( 합성고분자 -3) Soonchunhyang University Department of Chemical Engineering Prof. Jungkyun Im 순천향대 나노화학공학과 임정균교수
6. Diene Polymers: Natural and Synthetic Rubber Natural rubber is an unsaturated hydrocarbon polymer. Ziegler-Natta 촉매를이용하여인공적으로합성도가능하다. Latex (natural rubber) is obtained from the rubber tree. ( 열대수종의수액으로부터얻어짐 ) (cis) double bond가계속남아있고, Z geometry를갖고있다. (cis polymer)
Problem 9. Gutta-percha is also a polymer of isoprene with E double bonds. Draw the structural formula for a three-monomer segment. 힌트 : isopropene 의구조가다름. E E E gutta-percha 대부분의고무는원료와제조방법에따라다르지만보통분자량이 1백만을넘고이경우단량체가 15,000개이상이다. 천연 (Crude) rubber는폴리프로필렌이외에도 2.5~3.5% 의단백질, 2.5~3.2% 의지방, 0.1~1.2% 의물, 그리고소량의무기물이포함되어있다. 천연고무는가끔끈적거리거나불쾌한냄새가나거나더운날에는물렁물렁해지고추워지면딱딱해지는단점이있다. Vulcanization( 가황 ) 처리를하면폴리머사슬들이 cross linking( 가교 ) 을일으켜고무를더강하게만들수있다. 또한고무가늘어난후에다시원래의모양으로복원되는일종의 기억 으로작용한다.
1839 년에어떤호기심많은이가천연고무를좀더쓸모있는형태로만들게되었습니다. 이사람이세계적인기업가인찰스굿이어 (Charles Goodyear) 입니다. 그는천연고무가든항아리를들고부엌주위를배회하던중실수로유황을항아리에쏟아붇고말았습니다. 이우연한사고이후그는이황을머금은고무가녹지않고열을가하면끈적거리게되지도않는다는것을알게되었죠. 또한매우추운겨울날씨에도쉽게깨지지않는것을알아냈습니다. 그는이것을가황고무 (vulcanized rubber) 라불렀습니다.
그럼에도불구하고, 천연고무로타이어를만들경우타이어의공기압을자주체크해야했다. 고무가다소다공성 (porous) 이 있기때문이었다. 천연고무와유사하면서도화학적으로는개선된성질을가지는합성고무 (synthetic rubber) 가개발되었다. Elastomer: rubber-like polymer (25%) (75%) 대표적인 elastomer Styrene-butadiene rubber (SBR) 20% 의 butadiene은 1,4 addition이아닌 1,2 addition 방식으로중합되기도한다. 천연고무와달리 double bond는 E geometry를갖고있다. 점선은각단량체단위를보여준다. SBR의연간생산량은천연고무생산량의두배이상이다.
SBR 에 carbon black 이라는충진제를넣어서타이어의내구성을 10 배이상증가시킬수있다. ( 타이어가검은이유 ) Carbon black 은탄성체에가장널리사용되는충진제이며, 강직도, 인장강도, 내마모성등을향상시키는역할을한다. Problem 14.10 Draw the structural formula for a three-monomer segment of poly(1,3-butadiene) in which a. addition is 1,4 and double bonds are Z b. addition is 1,4 and double bonds are E c. addition is 1,2 for the middle unit and 1,4 for the outer units, with double bonds Z 1 2 Z-poly(1,3-butadiene) E-poly(1,3-butadiene) 4 3
7. Copolymers ( 공중합체 ) ( 단일중합체 ) 한가지 monomer 로부터만든폴리머 ( 공중합체 ) monomer mixture 로부터만든폴리머 Radical A reacts rapidly with B but slowly with A, and B reacts rapidly with A but slowly with B. alternating ABABAB-. Monomers A and B are equally reactive: random AABABBA-. Monomer A is much more reactive than B toward all radicals. A will be consumed first, followed more slowly by B. A mixture of two homopolymer: -(A) n -and-(b) m -
Problem 11. 1,1-dichloroethene and vinyl chloride form a copolymer. The monomer units tend to alternate in the chain. Draw the structural formula for a 4-monomer segment. Cl Cl Cl H Cl Cl Cl H Block copolymer 와 graft copolymer 는특별한방법으로만들어진다. Block copolymer: Monomer A 가모두중합시켜서소진하여 block A 를만들고, monomer B 를첨가하여중합을시작하면 block B 가만들어진다. Graft copolymer: Monomer A 로이루어진 homopolymer 를만든후, monomer B 를첨가하여 homopolymer 사슬에있는작용기 (double bond) 로부터새로운중합반응을시켜서새로운 block 을접목시킨다. Addition of free radical initiator R and second monomer (styrene) will graft onto the polybutadiene backbone. (backbone)
SBS 고무 (Poly(styrene-butadiene-styrene)) SBS고무 (Poly(styrene-butadiene-styrene), SBSR) 는딱딱한고무로서신발밑창, 타이어등과같이내구성이요구되는곳에사용된다. 블록공중합체로서단량체로서스티렌과부타디엔을사용하고있다. 아래그림과같이폴리스티렌사슬사이에폴리부타디엔사슬이연결된구조이다. (Block copolymer) PS (polystyrene) : glassy PB (polybutadiene) : rubbery
8. Step-Growth Polymerization: Dacron and Nylon Reaction between two monomers which are difunctional. (polyester)
Problem 13. What product will be formed if a diacid is treated with a large excess of a diol? If a diol is treated with a large excess of a diacid? O O HO 2 C CO 2 H + HO OH HO O C C O (large excess) diester-diol OH O O O O O O HO OH + HO C C OH HO C (large excess) C O O C diester-diacid C OH Problem 14. Kodel is a polyester with the following structure, from what two monomers is it made? HO 2 C CO 2 H and HOH 2 C CH 2 OH
Biodegradable polymers spun into fiber, textile (PET, PETE, Dacron(brand name)) Poly(lactic acid), (PLA) lactic acid ( 젖산 ) lactide (cyclic diester) a biodegradable thermoplastic aliphatic polyester
Nylon: polyamide step growth polymer (diacid) (diamine) (polyamide) spun into fibers 1938 년 Dupont 에서스타킹으로판매 (cyclic amide = lactam) (ring opening on heating) Nylon-6,10 등도있다.
9. Polyurethanes and Other-Step Growth Polymers urethane (carbamate) 의구조 : a single carbonyl group 에 ester 와 amide group 이있다. mechanism Polyurethane 은 diisocyanate 와 diol 의 step growth polymerization 으로얻어진다.
Problem 15. 1-Naphthyl-N-methylcarbamate is made from methyl isocyanate and 1-naphthol. Write the equation. OH CH 3 NH O C O + CH 3 N C O No small molecule is eliminated.
Polyurethane 을 foam( 포말 ) 형태로제조하고싶을때. polyurethane varnish( 니스 ) 물을소량첨가, 물은 isocyanate와반응이가능하다. 중간체인 carbamic acid는불안정하여쉽게분해되어 amine과 CO 2 를배출한다. 기포가생겨서 foam 형태가된다. 즉첨가된물의양으로 foam의밀도가결정된다. polyurethane foam 생성된 amine 은다시 isocyanate 와반응을해서 urea 를만들수가있다. 이것은 cross linking ( 가교 ) 역할을한다. Cross linking 이적을경우 : 신축성이우수한섬유 (Spandex, Lycra) 가된다.
Other step-growth polymers (electrophilic substitution reaction) (highly cross-linked, ortho- and para position 에 methylene group) Thermosetting polymer( 열경화성고분자 ): 가열하면가교가더진행되어딱딱하고불용성인물질로변함, 원래의상태로돌아가지않음. Bakelite 는기구손잡이, 고온에서견딜수있는 missile nose cone 의제조에쓰인다.
Ivory was highly prized for its beauty, durability, and suitability for carving. The teeth of the hippopotamus, walrus, narwhal, sperm whale, and some types of wild boar are also composed of ivory, however never found mcuh commercial value because of their small size. Since ancient times, ivory was used widely. ( 당구공, 피아노키, 칼손잡이 ) Unless a replacement had been found, elephants would now be extinct. There was a great need for a synthetic material to replace elephant-tusk ivory. In 1907, the Belgian chemist Leo Baekeland developed a synthetic replacement, called Bakelite. This is made by another polymerization process, between phenol and formaldehyde heated together. The reactions are complex, but the final result is a hard "plastic" made of crosslinked polymer chains. This was the first true synthetic material (there are no natural analogues). It was used for billiard balls, piano keys and knife handles from 1907, and rapidly replaced ivory.
Epoxy resin ( 에폭시수지 ) 금속, 유리, 세라믹등을붙이는접착제및페인트의원료
Mechanism of formation of Bakelite in the presence of base loss of water