Research On The Functional Modification And Applications Of Poly(methylsilane)

Polysilanes is a kind of potential functional materials.Electron-delocalization along the Si-Si chain gives polysilanes unique optical and electrical properties.Polymethylsilane?PMS?is a low-cost candidate with high reactivity,flexible chain and excellent solubility.The properties of PMS can be improved through post-functionalization by introducing new structure,obtaining prominent optical/electrical properties as a functional polymer materials.The ?-conjugation effect is affected by the side chain structure and the crosslinking structure.Firstly,this paper designs a series of substituents with similar chemical structure to analyze the affecting factors in polymer optical/electrical properties,and finds the general regularities to improve the optical and electrical properties of PMS,from the electronic effect,conjugation effect and volume effect respectively.Secondly,the large conjugated system and crosslinking modification are studied respectively.The composition,structure and properties of these modified PMS are carried on.Structure characterization,optical/electric properties,oxidation resistance,solubility and other properties are analysted in detail.The effects of side substituents on the properties of modified PMS is that electron attracting/donating effects can be significantly enhanced the optical/electrical properties of PMS.Among them,electronic attracting group will increase the number of polymer conformation and make substituents more freedom,which is easy to generate lower energy level structure.The ?-n-? modification structure containing heteroatom with lone pair electrons performs better properties than ?-? conjugate structure.The modified polymer containing N atoms has more excellent optical/electrical properties.However,O atoms replaced polymer tends to become more stable in the air.The volume effect of side groups influence main chain directly,for big volume groups can protect remaining active Si-H and thus improve the oxidation resistance of modified PMS.Large conjugated side group 5-hydrophenyl^-10,15,20-phenylporphyrin?MTHPP?is introduced into PMS successfully,which is connected to main chain by ?-n-? structure.The oxidation resistance,conductivity and optical properties of products are enhanced as MHTPP replace rate increased.The highest replace rate products with the best performance.The ultraviolet absorption peak of products?P=4.64?has greatly broaden,the red shift of its UV-spectra nearly 100 nm,the fluorescence characteristics of it is similar to MHTPP monomer,its conductivity can reach to10-2 S?cm^-1 after I2 doping.The solubility and film-forming performance of it is very good.MHTPP-PMS has solvatochromism properties: the maximum emission peaks of fluorescence are different in various solvents,which is related to the polarity and donor number of each solvent.Fluorescence emission spectrum of MHTPP-PMS will appear bigger red shift in more alkaline solvent with higher polarity.Crosslinking system will impact the performance of the modified PMS.When lone pair electrons atom O is used as main chain crosslinker,it is helpful to enhance optical/electrical properties of PMS.Comparing to linear structure,crosslinking ?-n-? structure show bigger ultraviolet redshift,stronger fluorescence,higher pristine conductivity?nearly six orders of magnitude about PMS?,and perform stronger resistance to oxidation.This low crosslinking degree causes little opposite effects on its solubility and film-forming property.Based on simple crosslinking modification system,5,10,15,20-phenylporphyrin?THPP?is designed to modify PMS.THPP-PMS with the conjugated porphyrin ring as the crosslinking-center,performs outstanding optical property and solubility.It is easy to make films that show strong fluorescence under ultraviolet light.The pristine conductivity of THPP-PMS is about 10-2 S?cm^-1,and can achieved to 101 S?cm^-1 after I2 doping.Modifications and preliminary applications of are studied in targeted functional side group modified PMS.Graphene modified polysilane has a stable structure,which consists of the graphene structure and grafted Si-Si long chain.As a new potential super capacitor materials,graphene modified polysilane performs an improved specific capacitance and energy comparing to graphene oxide.Based on the reactivity of Si-H,ester side group can grafted on Si-Si main chain.Alkyl ethylene carbonate modified PMS with high Si-H substitution,could enhance cycling stability for conventional lithium ion battery system both at room temperature and high temperature,as well as the high voltage battery system at room temperature.It is expected to be used in battery industry after further optimization.Using Si-H addition reaction,long chain carboxylic acids could be connected to Si-Si main chain successfully,which could bring polysilane materials good water solubility and obtain a stable amphiphilic membrane material.The relationship between structure and properties of modified PMS are discussed in this paper.Several side group and crosslinking structures which are able to effectively improve the optical and electrical properties are found.Crosslinking ?-n-? structure centered by large conjugated group could greatly improve the fluorescence properties?wavelength,intensity?and conductivity properties?pristine,doping?,which is expected to be used as functional polymer materials.